The post-inflationary Peccei-Quinn symmetry-breaking scenario provides a rich theoretical framework to study axion dark matter production through the dynamics oftopological defects. Accurate predictions for the axion abundance require a detailed understanding of the formation and evolution of cosmic strings and domain walls, which are inevitably produced in this scenario. Most existing studies rely on large-scale numerical simulations of the classical equations of motion, which are subject to significant systematic uncertainties. In this contribution, we briefly review the main features of the post-inflationary scenario and the current limitations in the literature, and present preliminary results from a new analytical framework for axion domain wall networks. Our approach is based on nonequilibrium quantum field theory. It employs the two-particle-irreducible effective action to derive effective Fokker-Planck equations for macroscopic quantities such as the average energy density and root-mean-square velocity of the this http URL discuss the relevance of thermal, self-interactions, plasma-induced and quantum effects for cosmological axion abundance estimates, with applications to QCD axions and high-mass axion-like particles.

The presence of supermassive black holes (SMBHs) at high redshifts ($z>5$), as revealed by James Webb Space Telescope (JWST), challenges standard black hole (BH) formation scenarios. We propose a mechanism in which non-annihilating dark matter (DM) with non-gravitational interactions with the Standard Model (SM) particles accumulates inside Population III (Pop III) stars, inducing their premature collapse into BH seeds having the same mass as the parent star. Owing to their early formation, these seeds can accrete for longer periods and grow into the SMBHs observed at early cosmic times. Focusing on spin-dependent (SD) DM-proton interactions, we identify regions of parameter space that account for the observed high-redshift SMBH population, their mass function, and the SMBH-stellar mass relation. Portions of this parameter space are testable by forthcoming direct detection experiments. The scenario may lead to distinctive gravitational wave (GW) signatures from SMBH mergers, accessible to Laser Interferometer Space Antenna (LISA) and pulsar timing array (PTA) observations.

We present a new determination of the strong coupling constant $\alpha_s$ from a global QCD analysis CT25 of parton distribution functions (PDFs) that incorporates high-precision experimental measurements from the Run-2 of the Large Hadron Collider together with a large sample of other measurements over a wide interval of energies. This work addresses two objectives: providing an up-to-date determination of $\alpha_s$ using NNLO calculations and a sensitive nucleon data set within a self-consistent framework, and critically assessing the robustness of the $\alpha_s(M_Z)$ extraction in light of systematic uncertainties as well as correlations of $\alpha_s(M_Z)$ with the functional forms of PDFs and other model parameters. In regard to the uncertainty assessment, we demonstrate that some commonly used criteria, including the dynamical tolerance and Bayesian hierarchical models, may produce significantly different or even unstable estimates for the net $\alpha_s$ uncertainty, and we introduce a concept of \textit{data-clustering safety} that the replicable uncertainty estimates must satisfy. Based on this in-depth examination of the CT25 global hadronic data set using a combination of analysis methods, and after demonstrating a weak correlation between $\alpha_s$ and the functional forms of CT25 PDF parametrizations, we find $\alpha_s(M_Z)=0.1183^{+0.0023}_{-0.0020}$ at the 68\% credibility level.

Bound-state formation (BSF) can have a large impact on annihilation of new physics particles with long-range interactions in the early Universe. In particular, the inclusion of excited bound states has been found to strongly reduce the dark matter abundance and qualitatively modify the associated freeze-out dynamics. While these effects can be captured by an effective annihilation cross section, its explicit computation is numerically expensive and therefore impractical for repeated use in Boltzmann solvers or parameter scans. In this work we present BSFfast, a lightweight numerical tool that provides precomputed, tabulated effective BSF cross sections for a wide class of phenomenologically relevant models, including highly excited bound states and, where applicable, the full network of radiative bound-to-bound transitions. We exploit rescaling relations of the cross section to efficiently cover models with additional free parameters and provide fast interpolation routines in Mathematica, python and C for use in Boltzmann solvers. As an illustration, we apply BSFfast to a superWIMP scenario with a colored mediator, demonstrating that the tool enables phenomenological studies that would otherwise be computationally prohibitive. The code is publicly available on GitHub.

We study the evolution of charm $(c)$ quarks in hot QCD matter with $N_f=2+1(+1)$ quark flavors by analyzing the charm production rate and the time dependence of their abundance. Microscopically, the system is described within a quasiparticle model, in which interactions among dynamical quarks and gluons are encoded in their effective masses with the running coupling constrained by lattice QCD data. We investigate $c$-quark kinetics in a longitudinally propagating perfect fluid as well as in a viscous medium undergoing (2+1)D expansion, and find that the charm production rate decreases monotonically across all medium formulations. In the $N_f=2+1+1$ scenario, charm production is systematically suppressed due to the effective mass of heavy quasiparticles. Assuming an initial charm yield given by the Statistical Hadronization Model, we solve the rate equation and compute the total charm abundance in hot QCD medium. For all descriptions considered, the charm quark number remains approximately conserved, consistent with existing experimental evidence.

In this article we explore ideas from quantum entanglement which can be meaningfully formulated and tested in the collider environment. We propose Bell-type inequalities as operator-level diagnostics of quantum incompatibility in particle-physics systems. We construct flavor operators associated with mass identification, flavor change, and charged-current weak mixing which arise from fundamental interactions in the Standard Model. We treat these interactions as alternative measurement settings in a Gendanken experiment. For entangled two-particle states, these operators generate nontrivial correlations that violate Bell-type bounds, excluding non-contextual local descriptions under the stated assumptions. These violations arise from the algebraic structure of the operators rather than from kinematic correlations or exotic dynamics. We discuss how the predicted correlation patterns may be probed with experimental data, clarifying the scope and limitations of Bell-type reasoning in particle physics.

This talk at the CPT'25 meeting presents an overview of some recent results in Lorentz and CPT violation. Topics covered include the geometry of Finsler spaces associated with Lorentz violation, the resolution of the concordance problem in Lorentz-violating effective field theories, the relativistic evolution of a spin in background fields, and the phenomenology of searches for flavor-changing Lorentz and CPT violation in charged leptons.

Clarifying the origin of hadron mass is one of the fundamental problems in particle physics, relevant from hadronic scales to astrophysical observations. At low energies, this issue is reflected in the decomposition of the hadron mass into chiral-variant and -invariant components. In this letter, we propose a method to extract the chiral invariant mass from the gravitational $D$-form factor under the assumption of the lightest-sigma meson dominance. Focusing on the nucleon, we show that a sizable chiral invariant mass is required to reproduce lattice QCD data, consistent with neutron star constraints.

Motivated by the cosmological collider program, which aims to probe high-energy physics through inflation, we investigate the phase diagram of multi-flavor QCD in de Sitter spacetime with a flavor-universal axial chemical potential induced by a rolling inflaton coupled to fermions. We determine the first-order critical line and a critical point as functions of the Hubble parameter and the axial chemical potential, employing an effective description of chiral symmetry breaking within the framework of the Nambu--Jona-Lasinio model. We find that a first-order chiral phase transition may occur during inflation or at its end when the axial chemical potential is sufficiently large and crosses the critical line. This provides a cosmological collider analogue of the QCD phase diagram explored in heavy-ion colliders.

We propose a novel framework for low-scale leptogenesis within an extension of the Standard Model (SM) that includes three SU(2) singlet right-handed neutrinos, a singlet charged neutral fermion, and a real scalar field. In this setup, the CP asymmetry arises through a rich interplay of mechanisms, including two-body decays of the lightest right-handed neutrino into leptons and Higgs or into dark-sector particles, as well as multiple 2 -> 2 scattering processes involving visible and dark states. Crucially, the CP-violating phases originate not only from conventional vertex and self-energy corrections but also from novel interference effects mediated by the dark sector, which significantly enrich the sources of asymmetry. A distinctive feature of our model is the direct connection between the dark sector and leptogenesis, providing a unified explanation for both the matter-antimatter asymmetry and DM abundance. This connection leads to enhanced CP violation in neutrino interactions and predicts new dark-sector particles accessible at the LHC.

The mass spectrum of hadrons in magnetic fields features avoided level-crossing structures arising from the mixing of spin eigenstates. In this work, we investigate the impact of level-crossing dynamics of charmonia subjected to time-dependent magnetic fields, where we particularly focus on the occupation probabilities of two or more states as they undergo transitions at avoided crossings. Using a static spectrum of charmonia in magnetic fields, we construct a multi-channel Landau-Zener Hamiltonian. Within this framework, we analyze the time evolution under several representative magnetic-field profiles, including linear ramps and Gaussian decays corresponding to single-passage dynamics, as well as Gaussian pulses realizing double-passage dynamics, and compute the occupation probabilities over a wide range of sweep rates and initial conditions. Our results show that nonadiabatic dynamics, including Landau-Zener transitions and Stückelberg interference, strongly influences the occupation probabilities of charmonia. These findings provide new insights into the real-time dynamics of magnetized hadrons and offer useful guidance for future lattice simulation studies.

Parton Distribution Functions (PDFs) play a central role in describing experimental data at colliders and provide insight into the structure of nucleons. As the LHC enters an era of high-precision measurements, a robust PDF determination with a reliable uncertainty quantification has become mandatory in order to match the experimental precision. The NNPDF collaboration has pioneered the use of Machine Learning (ML) techniques for PDF determinations, using Neural Networks (NNs) to parametrise the unknown PDFs in a flexible and unbiased way. The NNs are then trained on experimental data by means of stochastic gradient descent algorithms. The statistical robustness of the results is validated by extensive closure tests using synthetic data. In this work, we develop a theoretical framework based on the Neural Tangent Kernel (NTK) to analyse the training dynamics of neural networks. This approach allows us to derive, under precise assumptions, an analytical description of the neural network evolution during training, enabling a quantitative understanding of the training process. Having an analytical handle on the training dynamics allows us to clarify the role of the NN architecture and the impact of the experimental data in a transparent way. Similarly, we are able to describe the evolution of the covariance of the NN output during training, providing a quantitative description of how uncertainties are propagated from the data to the fitted function. While our results are not a substitute for PDF fitting, they do provide a powerful diagnostic tool to assess the robustness of current fitting methodologies. Beyond its relevance for particle physics phenomenology, our analysis of PDF determinations provides a testbed to apply theoretical ideas about the learning process developed in the ML community.

We discuss a double seesaw mechanism for generating light neutrino masses within the Standard Model extensions that include both right-handed neutrinos and extra gauge-singlet sterile fermions. The flavour structure of the double seesaw framework is invoked by an $A_4$ discrete symmetry which yields predictive textures for the Dirac neutrino mass matrix $M_D$, the mixing matrix $M_{RS}$ connecting right-handed and sterile neutrinos, and the bare Majorana mass matrix $M_S$ for the sterile neutrinos. The interesting feature of the present framework is that the combination of the double seesaw mechanism and $A_4$ flavour alignments yields a leading-order TBM structure, corrected by a single rotation in the (1-3) sector. We also derive analytic expressions for the heavy sterile eigenvalues and for the resulting light neutrino masses, thereby clarifying the role of the symmetry in shaping the neutrino mass hierarchy. We further incorporate the most recent JUNO measurements, which improve the precision of the solar mixing angle $\sin^2\theta_{12} \simeq 0.31$, along with updated constraints on $\sin^2\theta_{13}$. We show that these results significantly restrict the allowed parameter space of the model. In particular, the observed value of $\sin^2\theta_{12}$ constrains the magnitude of the (1--3) rotation and the phases associated with the $A_4$ flavon couplings, while the value of $\sin^2\theta_{13}$ sharpens these restrictions further. Overall, the interplay between double seesaw dynamics, $A_4$ flavour symmetry, and the recent JUNO constraints yields a highly predictive framework for neutrino masses and mixings, offering a coherent explanation for the generation of light neutrino masses and testable predictions for future experiments.

The Minimal R-symmetric Supersymmetric Standard Model with Seesaw (MRSSMSeesaw) extends the MRSSM by incorporating right-handed neutrinos to generate neutrino masses via the Type-I seesaw mechanism. This work presents a detailed analysis of lepton flavor violation (LFV) processes, including $\ell_i \rightarrow \ell_j \gamma$, $\ell_i \rightarrow 3\ell_j$, and Higgs decays $h \rightarrow \ell_i \ell_j$, Based on the current experimental limitations, we carry out detailed parameter scanning and numerical calculations to analyse the effects of different sensitive parameters on this http URL numerical results show that the non-diagonal elements involving the initial and final leptons are main sensitive parameters and LFV sources.

We study the impact of background-induced forces on dark matter (DM) annihilation and their implications for indirect detection. In the presence of a finite number density of background particles, loop-level interactions can generate an effective force that is significantly enhanced relative to the vacuum case. We construct a two-component DM model in which the dominant component is a fermionic particle $\chi$ and the subdominant component is an ultralight pseudoscalar particle $\phi$. The annihilation of $\chi$ proceeds through the p-wave channel and produces gamma-ray emission. The finite density of $\phi$ particles induces a background-enhanced force between $\chi$ particles, leading to a sizable Sommerfeld enhancement of the annihilation. We show that a viable region of parameter space in this model can account for the gamma-ray excess observed in the Galactic Center using Fermi-LAT data. The background-induced force substantially amplifies the Sommerfeld enhancement and thus enlarges the parameter space capable of explaining the excess, highlighting the importance of background effects in astrophysical environments.

We investigate a Standard Model extension containing $n$ degenerate down-type isosinglet vector-like quarks (VLQs) with masses $M_{\mathcal D}$ and Yukawa couplings $y_{\mathcal D}$, supplemented by a single right-handed neutrino (RHN), aiming to simultaneously address neutrino mass generation, electroweak vacuum stability, and Higgs inflation. The VLQs play the dominant role in stabilizing the Higgs potential through their impact on the renormalization-group evolution, while the RHN generates light neutrino masses via a Type-I seesaw mechanism and smooths the high-scale running of the Higgs quartic coupling in the inflationary regime. We perform a two-loop Standard Model renormalization-group equation analysis supplemented by the one-loop contributions of the VLQs and the RHN, with proper matching across their mass thresholds. Using these RG trajectories, we identify the regions in $(n,\, y_{\mathcal D},\, M_{\mathcal D})$ that stabilize the Higgs potential up to the Planck scale while satisfying experimental constraints. Employing the RG-improved Higgs potential in the metric formulation of non-minimal Higgs inflation, we compute the inflationary observables $n_s$ and $r$. The SM+$(n)$VLQ+RHN framework yields predictions consistent with the combined Planck, WMAP, and BICEP/Keck data, while simultaneously ensuring electroweak vacuum stability and phenomenologically viable neutrino masses within well-defined regions of parameter space. For comparison, we also investigate the SM+$(n)$VLQ limit and present its vacuum stability and Higgs inflation predictions as a reference to quantify the stabilizing role of the VLQ sector.

Over the past two decades, numerous exotic hadron states have been discovered, yet their underlying nature remains unclear. It is widely acknowledged that understanding hadron-hadron interactions is essential to unraveling their properties. Hadron spectroscopy is a powerful tool for this endeavor, providing rich experimental data that can shed light on exotic systems. Recently, the LHCb experiment analyzed the process $B^{-} \rightarrow J/\psi \Lambda \bar{p}$ and observed a narrow peak in the $J/\psi \Lambda$ invariant mass spectrum, regarding it as a candidate for a pentaquark. In this work, we extract the coupled-channel $J / \psi \Lambda-\bar{D} \Xi_c-\bar{D}_s \Lambda_c$ potential based on the $J/\psi \Lambda$ invariant mass spectrum. Our results indicate the existence of a bound state below the $\bar{D} \Xi_c$ mass threshold, corresponding to the experimentally measured state $P_{cs}(4338)$. Furthermore, we predict the scattering lengths and momentum correlation functions for the $J/\psi \Lambda$ and $\bar{D}\Xi_c$ channels, which serve as theoretical references for future femtoscopy experiments.

We present a model calculation to reproduce the differential mass distribution for the $D^*\pi$ system in the reactions $B^- \to D^{*+} \pi^- \pi^-$ and $B^{+}\to D_s^+D^{*-}\pi^{+}$ analyzed by the LHCb Collaboration, which shows a dominant signal for $D_1(2420)$. %\textbf{We} (The idea is to) We consider a model based on coupled channel meson-meson interactions that can describe the properties of $D_1(2420)$ in terms of the underlying dynamics, use it to determine the invariant mass distribution of the $D^*\pi$ system, and compare the results with the experimental data. We also determine the $D^*\pi$ scattering length, for which different values are available from different sources, leading to a controversy. To our knowledge, this is the first attempt to reproduce the mentioned data using model calculations. Our formalism relies on the hadronization of different mesons through a weak decay, allowing for the final-state (strong) interactions among the relevant constituents. We benefit from our previous work when obtaining the amplitudes corresponding to the strong interactions. We hope that our findings can be useful in further investigations of the properties of $D_1(2420)$.

In the Minimal Supersymmetric Standard Model (MSSM), compressed Higgsinos spectrum ($\Delta m^0 \lesssim 1$ GeV) occurs when $|\mu| \ll |M_1|, |M_2|$ and ${\rm sign}(M_1\cdot M_2)<0$, which leads to a long-lived next-to-lightest neutralino. Such a long-lived neutralino could be copiously produced at the LHC, however escape the detection at the LHC main detectors. We examine the discovery potential at the FASER experiment and find that the FASER 2 could cover the neutral Higgsino mass up to about 130 GeV with mass splitting between 4 to 30 MeV. It is complementary to both the LHC Higgsino search in the $\Delta m^{0,\pm} \gtrsim 1$ GeV region, and displaced vertex and disappearing track searches of charginos with $\Delta m^\pm \lesssim 1$ GeV.

We present the analytic integration of the iterated single unresolved subtraction terms in the extension of the CoLoRFulNNLO subtraction scheme to color-singlet production in hadron collisions. We exploit the fact that, in this scheme, subtraction terms are defined through momentum mappings which lead to exact phase space convolutions for real emissions. This allows us to write the integrated subtraction terms as parametric integrals, which can be evaluated using standard tools. Finally, we show that the integrated iterated single unresolved approximate cross section can be written as a convolution of the Born cross section with an appropriately defined insertion operator.

I present some memories of my Ph.D supervisor and, later, collaborator but always encouraging supporter Prof. G. Lazarides. Some of his contributions to our common and related scientific activities on the phenomenology of MSSM and inflation are also summarized.

To shed light on the inner structure of the observed single-bottom strange baryons, in this work we systematically study the Okubo-Zweig-Iizuka allowed strong decay properties of $1P$- and $2S$-wave $\Xi_b$ and $\Xi_b'$ baryons within the $j-j$ coupling scheme in the framework of the quark pair creation model. For a comparison, we also give the predictions of the chiral quark model. The calculations indicate that: (i) The $1P$-wave $\lambda$-mode $\Xi_b$ states $\Xi_b|J^P=1/2^-,1\rangle_{\lambda}$ and $\Xi_b|J^P=3/2^-,1\rangle_{\lambda}$ are highly promising candidates for the observed state $\Xi_b(6087)$ and $\Xi_b(6095)/\Xi_b(6100)$, respectively. The $1P$-wave $\rho$-mode $\Xi_b$ states $\Xi_b|J^P=3/2^-,2\rangle_{\rho}$ and $\Xi_b|J^P=5/2^-,2\rangle_{\rho}$ are likely candidates for the state $\Xi_b(6227)$. Meanwhile, we cannot rule out the possibility that $\Xi_b(6227)$ could be a candidate of the $1P$-wave $\lambda$-mode $\Xi_b'$ state $\Xi_b'|J^P=3/2^-,2\rangle_{\lambda}$ or $\Xi_b'|J^P=5/2^-,2\rangle_{\lambda}$. (ii) For the other $1P$-wave $\rho$-mode $\Xi_b$ states and $1P$-wave $\lambda$-mode $\Xi_b'$ states, they may be moderate states with a width of several tens of MeV. Their main decay channels are $\Xi_b\pi$, $\Xi_b'\pi$, $\Xi_b^*\pi$ or $\Lambda_b\bar{K}$. The width of the $1P$-wave $\rho$-mode $\Xi_b'$ states are slightly broader, approximately several tens to over one hundred MeV, and the dominant decay channels are $\Xi_b'\pi$, $\Xi_b^*\pi$, $\Sigma_bK$ or $\Sigma_b^*K$. (iii) The $2S$-wave $\lambda$-mode $\Xi_b$ and $\Xi_b'$ states are most likely to be relatively narrow state with a width of only a few to around ten MeV, and they mainly decay into $\Xi_b'\pi$ or $\Xi_b^*\pi$. In addition, the $2S$-wave $\lambda$-mode $\Xi_b'$ states may also mainly decay into the $1P$-wave $\Xi_b$ baryon via the pionic decay processes.

We examine Sommerfeld enhancement in dark matter annihilation as a potential origin of the halo-like gamma-ray excess near $E_\gamma \simeq 20$ GeV reported by Totani. A minimal model with a light CP-even scalar mediator naturally produces a velocity-dependent annihilation cross section consistent with thermal freeze-out, the Milky Way excess, and limits from dwarf spheroidal galaxies.

Following the experimental confirmation of tetraquark and pentaquark states, the search for hexaquark states has emerged as a new frontier in hadron physics. Recent experimental progress, particularly by the BESIII collaboration, has provided compelling evidence for the existence of near-threshold $p\bar{p}$ bound states. These baryon-antibaryon systems, commonly referred to as baryoniums, are regarded as promising hexaquark candidates. In this article, we provide a comprehensive review of the investigations into baryonium states and their constituents, i.e., baryons, within the framework of QCD sum rules. We delineate the fundamental calculation procedures of this method to facilitate its practical application and benchmark the theoretical predictions against alternative models as well as the latest experimental data.

An extension of the Standard Model with $\Gamma_2\simeq S_3$ modular flavor symmetry is presented. We consider the construction of the lepton sector, augmented by two right-handed neutrino states, in the vicinity of the fixed points $\tau = i\infty $ and $\tau = i$. Due to the residual symmetries at these points, and with the aid of non-holomorphic modular forms (which constitute representations of $S_3$) and by assigning specific transformation properties to the fermion fields, highly economical models (without flavon fields) are constructed with interesting Yukawa textures. All presented models strongly prefer the inverted ordering for the neutrino masses.

The dark sector may possess a rich structure yet to be uncovered, and a QCD-like dark sector with GeV-scale dark hadrons can yield novel signatures at the Large Hadron Collider (LHC). In this work, we focus on a light singlet pseudoscalar mediator that connects the QCD-like dark sector to the Standard Model (SM) sector via the Higgs portal. Notably, when the lightest unstable dark meson has a mass of approximately $3$ GeV, it predominantly decays into a pair of gluons and behaves as a long-lived particle, a scenario that has received relatively little attention. We consider various Higgs production channels at the LHC and investigate two processes for generating dark mesons: (1) the cascade decay of the Higgs boson into a pair of light pseudoscalar mediators, which subsequently decay into four dark mesons; and (2) the dark shower and hadronization process whereby the Higgs boson decays into a pair of dark quarks that subsequently evolve into dark mesons. These processes give rise to novel gluon-rich dark jets composed of long-lived dark mesons. Notably, we find that appropriate trigger selection constitutes a crucial factor for detecting these signal signatures in both tracker system and CMS muon system. At the high-luminosity LHC, the exotic Higgs branching ratio to cascade decays (dark showers) can be constrained below $\mathcal{O}(10^{-5}-10^{-1})$ [$\mathcal{O}(10^{-5}-10^{-2})$] for dark meson proper lifetimes $c\tau$ ranging from $1$ mm to $100$ m.

Recent studies have shown that hadronic multiplicity in deep inelastic scattering is associated with an entanglement entropy. However, such definitions are intrinsically longitudinal and do not capture the full phase--space structure of the proton. In this work, we investigate the Wehrl entropy of the proton constructed from Husimi distribution obtained from the Gaussian smearing of the Wigner distribution. We show that the entanglement entropy naturally emerges from the normalization condition of the Husimi distribution within this framework. In addition, the Wehrl entropy contains a contribution associated with transverse degrees of freedom. Numerical results for the proton Wehrl entropy are presented for different values of the virtuality.

The observation of resonant di-Higgs production, which would strongly suggest the existence of a new heavy neutral scalar $H$, has been searched for extensively at the LHC. In the two-Higgs-doublet model (2HDM) with $m_H\gg m_h$, where $h$ is the Higgs boson of mass 125 GeV observed at the LHC, we show that a direct correlation between Br$(H\to hh)$ and Br$(H\to VV)$, with $V=Z,W$, emerges that depends only on $m_H$ (and $m_V$). In particular, for heavy scalar masses between 500\,GeV and 1\,TeV, we find that Br($H\to hh$)/ Br($H\to ZZ)\approx 9.5$. The origin of this prediction is most transparent in the Higgs basis, where the term in the scalar potential proportional to $\mathcal H_1^\dagger \mathcal H_1 \mathcal H_1^\dagger \mathcal H_2$ (and its hermitian conjugate) generates the leading contributions to the $Hhh$ and $Hhhh$ couplings in the decoupling limit of the 2HDM. Moreover, the latter coupling governs the resonant prompt tri-Higgs production via $H\to hhh$, which is also directly correlated to $H\to hh$ and $(H\to VV)$, and can yield rates large enough to be measured at the High-Luminosity LHC.

We analyze the mass spectra of hadrons and demonstrate that the physical spectra of mesons and baryons are well described by the exponential spectrum of open strings. The open string spectrum, derived from string theory, is characterized by a unique Hagedorn temperature $T_{\rm H}$ and free from any other parameters. Notably, our fitting to the physical spectra yields consistent values for both mesons and baryons, $T_{\rm H} \simeq 0.34\,\text{GeV}$, which contrasts with previous phenomenological analyses that suggested different values. This obtained value aligns well with typical string tension derived from lattice-QCD calculations and the Regge slope. In the baryonic sector, our results indicate that diquarks play a crucial role in describing the mass spectrum, implying that baryons can be understood as a quark-diquark system, as anticipated by Regge phenomenology. These findings have significant implications for our understanding of quark deconfinement, especially in the possibly existing regime at high temperature and small baryon chemical potential within the QCD phase diagram.

We calculate the in-medium valence quark distribution of the pion immersed in a finite baryon density using the light-cone quark model. The medium-modified pion properties are obtained by using the constituent quark mass-dependent light cone wave functions. To obtain the constituent quark masses at finite baryon density, we employ the two-flavor Nambu--Jona-Lasinio model. We primarily focus on the in-medium electromagnetic form factor, distribution amplitude, and the parton distribution function of the pion. The parton distribution functions are also evolved from the model scale to a perturbative scale using next to leading order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations. Furthermore, our calculated form factors are compared with available experimental measurements and lattice quantum chromodynamics studies. We also examine the Mellin moments derived from our parton distribution functions in comparison with existing extractions and theoretical model predictions.

The left-right symmetric model (LRSM) could not only restore parity of the weak interaction, but also provide natural explanations of the tiny active neutrino masses via the seesaw mechanisms. The $SU(2)_R$-breaking scalar $H_3$ can induce lepton flavor violating (LFV) effects in the minimal version of LRSM at the 1-loop order, originating from the mixing of heavy right-handed neutrinos. If $H_3$ is light, say below the GeV scale, it will lead to rich signals, e.g. the LFV muon and tauon decays $\ell_\beta \to \ell_\alpha + X$ ($X$ being either visible or invisible final states) and the anomalous supernova signatures. Combined with the diphoton coupling of $H_3$, the right-handed scale $v_R$ is excluded up to $2\times10^9$ GeV. In the future, the $v_R$ scale can be probed up to $5\times10^9$ GeV in high-precision muon experiments, and further up to $6\times10^{11}$ GeV by supernova observations.

We develop a universal seesaw version of the Pati-Salam model wherein quarks and leptons of each family are unified into common multiplets transforming as $\psi_L(2,1,4))+ \psi_R((1,2,4)$ under the $SU(2)_L \times SU(2)_R \times SU(4)_c$ gauge symmetry. Parity symmetry is spontaneously broken in the model, which helps in solving the strong CP problem without the axion. The Higgs sector of the model is very simple, consisting of a single pair of $H_L(2,1,4)+ H_R(1,2,4)$ fields. Fermion masses arise through mixing of the chiral fermions with vector-like quarks and leptons contained in $(1,1,15)$ as well as $(1,1,10)_L+(1,1,10)_R$ multiplets via a universal seesaw mechanism. Consistency of such a spectrum with the observed quark and lepton masses is established. The parity solution to the strong CP problem is shown to be effective in this framework, although there are new loop contributions to $\overline{\theta}$, compared to the analogous left-right symmetric model, arising from color sextet and octet fermions, as well as from diagrams mediated by leptoquark bosons. We also find that, in this setup, although lepton number is broken, neutrino masses remain zero at the tree-level. Small and finite Majorana neutrino masses are induced via one-loop diagrams, which we analyze and show to be compatible with oscillation experiments.

We develop a general effective field theory (EFT) framework for neutrino-dark matter (DM) interactions, and apply it to systematically find all possible gauge-invariant ultraviolet (UV) completions at a given EFT operator dimension. Our goal here is to find simple UV-complete models that can realize potentially large neutrino-DM interactions, while being consistent with all existing theoretical and experimental constraints. We first construct the leading non-derivative operator basis for neutrino-DM scattering in a low-energy effective theory with neutrinos and DM (DM-LEFT), together with its gauge-invariant embedding in the Standard Model EFT (DM-SMEFT). We then construct all renormalizable tree-level UV completions that generate the relevant DM-SMEFT operators up to dimension-8 using a topology-based classification. Using this framework, we present minimal UV-complete models for different DM types that can yield effective neutrino-DM couplings up to several orders of magnitude larger than the Fermi coupling, while satisfying all constraints, most notably from neutrino mass and from the charged-lepton sector. This includes a pseudo-Dirac fermion DM realization in the scotogenic neutrino mass model and models of Majorana DM inspired by type-II and inverse seesaw-based neutrino mass models. Phenomenological implications for DM thermal relic abundance and direct detection prospects, as well as various cosmological and laboratory constraints on the model parameter space, are also analyzed.

The microscopic composition of neutron star interiors remains uncertain, with possible scenarios including nucleonic matter, hyperonic matter, dark matter admixed cores, and strange self-bound matter. Traditional constraints on the equation of state rely on Tolman Oppenheimer Volkoff modelling and comparison with multimessenger observations, but machine learning provides a complementary pathway by learning composition dependent patterns directly from astrophysically accessible observables. This work presents a compact supervised learning framework for EOS family classification using stellar properties derived from TOV modelling, asteroseismology, and gravitational wave descriptors. A labelled dataset of neutron star configurations spanning four EOS families (nucleonic, strange matter, dark matter admixed, and hyperonic) is constructed using seven input features: gravitational mass, radius, fundamental f mode frequency, quadrupole moment, redshift, damping time, and characteristic strain. A multilayer perceptron is trained to infer the underlying matter composition. On a held out test set, the classifier achieves an accuracy of 97.4 percent with strong class wise precision and recall. Permutation based feature importance analysis shows that oscillation related quantities, especially the f mode frequency and damping time, dominate the discriminatory power, while mass and radius provide secondary support. Residual misclassifications occur in physically intuitive regions where different EOS families produce partially overlapping macroscopic signatures. These results show that lightweight neural models can reliably identify EOS family fingerprints from a modest set of observables, providing a reproducible baseline for future extensions incorporating Bayesian uncertainty and observational posteriors from NICER and gravitational wave events.

Several recent works have revealed a simplicity in equal-time correlators that is absent in their wavefunction counterparts. In this letter, we show that this arises from the simple fact that the correlator is obtained by integrating Feynman propagators over the full spacetime, as opposed to the half-space for the wavefunction. Several striking new properties of correlators for any graph are made obvious from this picture. Certain patterns of poles that appear in the wavefunction do not appear in the correlator. The correlator also enjoys several remarkable factorization properties in various limits. Most strikingly, the correlator admits a systematic Laurent expansion in the neighborhood of every pole, with the first subleading term vanishing for every pole. There is an especially simple understanding of the expansion around the total energy pole up to second order, given by a differential operator acting on the amplitude. Finally, we show how these results extend beyond single graphs to the full correlator in Tr $\phi^3$ theory.

We consider a novel scenario for a strongly coupled spectator sector during inflation, that of a higher dimensional conformal field theory with large anomalous dimensions -- ``unparticles" -- and compactify the extra dimensions. More specifically, we take generalized free fields in five dimensions, where the extra dimension is compactified to a circle. Due to the usual Kaluza-Klein mechanism, the resulting excitations carry properties of both particles and unparticles, so we dub this scenario ``gapped unparticles". We derive a two-point function of the gapped unparticles by performing dimensional reduction. We then compute, in the collapsed limit, the four-point correlation function of conformally coupled scalars exchanging a gapped unparticle, which are used as seed functions to obtain the correlation function of primordial density perturbations. The phenomenology of the resulting correlators presents some novel features, such as oscillations with an envelope controlled by the anomalous dimension, rather than the usual value of 3/2. Depending on the value of the five-dimensional scaling dimension and effective mass of the gapped unparticles, we find a clear strategy to distinguish gapped unparticles from heavy massive scalars. If we assume the interactions are localized on a brane, gapped unparticles with different effective masses will share a universal coupling, and their exchanges produce an interesting interference pattern.

Loops of cosmic string experience a recoil from anisotropic gravitational radiation, known as the rocket effect, which influences the extent to which they are captured by galaxies during structure formation. Analytical studies have reached different conclusions regarding loop capture in galaxies: early treatments argued for efficient capture, while later analyses incorporating the loop rocket force throughout halo formation found that capture efficiency is reduced and strongly dependent on loop size. In this work, we employ the N-body simulation code GADGET-4, introducing non-backreacting tracer particles subject to a constant recoil force to model cosmic string loops with the rocket effect. We simulate the formation of a Milky-Way-like halo from redshift $z=127$ to $z=0$, considering loop populations characterized by a range of length parameters $\xi$, inversely proportional to the rocket acceleration. We find that the number of captured loops exhibits a pronounced peak at $\xi_{\textrm{peak}}\simeq 12.5$, arising from the competition between rocket-driven ejection at small $\xi$ and the declining intrinsic loop abundance at large $\xi$. For fiducial string tensions, this corresponds to $\mathcal{O}(10^6)$ loops within the halo. We further find that loops with weak rocket forces closely trace the dark-matter distribution, while those subject to stronger recoil but still captured -- particularly the most abundant loops near $\xi_{\textrm{peak}}$ -- are preferentially concentrated toward the central regions of the halo.

We develop a bottom-up formulation of spin-kinetic theory for hot and/or dense plasmas. We introduce scalar and axial-vector phase-space functions as dynamical variables that parametrize both spin-averaged and spin-dependent distribution functions. Using spin-dependent Poisson brackets, we derive the corresponding kinetic equations and construct the associated Schwinger-Keldysh action. We further demonstrate how physical observables can be expressed in terms of these dynamical variables through constitutive relations. In the linear response regime, we establish a precise matching between the kinetic-theory and field-theory descriptions of vector and axial Wigner functions under electromagnetic and gravitational perturbations. Our framework provides a complementary approach to describing the dynamics of spin effects in a medium.

The Steinmann relations are known to be violated with respect to some -- but not all -- two-particle momentum channels in massless Feynman integrals. We trace the source of this Steinmann violation to a special class of singularities, which arise from partially-overlapping minimal cuts. This allows us to propose an efficient graphical test for predicting which Steinmann relations will be violated by massless Feynman integrals of a given topology, which can be applied at any loop order. We provide evidence for this test by correctly predicting all instances of Steinmann violation in the complete set of known two-loop integrals that contribute to five-particle scattering with one or two external masses.

The reported evidence for an isotropic gravitational-wave background (GWB) from pulsar timing array (PTA) collaborations has motivated searches for extrinsic and intrinsic anisotropies. Kinematic anisotropies may arise as a consequence of a boosted observer moving with respect to the frame in which the GWB appears isotropic. In this work, we present an analytical toolbox to describe the effects of kinematic anisotropies on the overlap reduction function. Our analytical results differ from previous findings at the quadrupole order and are detailed in three appendices. For the first time, we also derive the corresponding auto-correlation using two approaches, taking the pulsar distances to be infinite or finite, respectively. Our formulas can be used in forecasts or Bayesian analysis pipelines.

We investigate the imprint of $\alpha$ clustering on initial spin fluctuations in relativistic $^{16}\mathrm{O}+{}^{16}\mathrm{O}$ and $^{20}\mathrm{Ne}+{}^{20}\mathrm{Ne}$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.36$~TeV. Utilizing \textit{ab initio} configurations from Nuclear Lattice Effective Field Theory (NLEFT) and phenomenological $\alpha$-cluster models within a Monte-Carlo Glauber framework, we compute the event-by-event variance of the initial net spin polarization. We find that the strong short-range spin--isospin correlations characteristic of $\alpha$ clusters lead to a significant suppression of spin fluctuations compared to a spherical Woods--Saxon baseline with uncorrelated spins. By constructing a scaled fluctuation observable that accounts for trivial finite-size effects, we demonstrate that this suppression exhibits a non-monotonic centrality dependence sensitive to the detailed cluster geometry. Furthermore, we propose the ratio of scaled spin fluctuations between $^{20}\mathrm{Ne}$ and $^{16}\mathrm{O}$ systems as a robust probe. Our results predict distinct percent-level deviations from the baseline for clustered nuclei, suggesting that measurements of final-state $\Lambda$-hyperon spin correlations can provide novel constraints on the ground-state spin structure of light nuclei.

The jet quenching phenomenon in an anisotropic quark-gluon plasma is studied using gauge-gravity duality. We consider a more general orientation of the contour of a lightlike Wilson loop in the boundary field theory. The Nambu-Goto action for a two-dimensional worldsheet, whose boundary is this contour, is evaluated in a five-dimensional bulk. We present the dependence of the jet quenching parameter on the orientation. Discontinuities of the jet quenching parameter occur at a first-order phase transition, and their magnitude depends on the orientation. These dependencies are observed in holographic models for both light and heavy quarks with nonzero temperature, chemical potential, magnetic field, and spatial anisotropy, supported by an Einstein-dilaton-three-Maxwell action.

We study the cosmological impact of a transient self-interaction phase in Ultra-Light Dark Matter (ULDM), focusing on its simultaneous effects on the sound horizon and the late-time growth of structure. In the presence of a quartic self-interaction, the scalar field undergoes a short-lived radiation-like phase before evolving into matter-like behaviour, inducing a localized modification of the expansion history at early times. We develop a perturbative and model-independent framework in which the self-interaction energy density is parametrized as a localized contribution to the total energy budget. Within this approach, the responses of the sound horizon and the linear growth factor can be expressed as weighted integrals over cosmic time, with distinct kernels encoding the temporal sensitivity of each observable. This structure leads to a simple analytic relation linking the corresponding early- and late-time responses, and naturally predicts correlated shifts in $H_0$ and $S_8$ whose sign and magnitude depend on the timing of the self-interaction episode. Our results show that a single transient modification of the expansion history can interpolate between early-time effects on the sound horizon and late-time suppression of structure growth within a unified physical framework, providing an analytical understanding of their joint response.

We report a state-of-the-art lattice QCD calculation of the total gluon helicity contribution to proton spin, $\Delta G$. The calculation is done on ensembles at three different lattice spacings $a=\{0.08, 0.09, 0.11\}$ fm. By employing distillation + momentum smearing for proton external states, we extract the bare matrix elements of the topological current $K^\mu$ under the 5-HYP smeared Coulomb gauge fixing configurations. Furthermore, we apply a non-perturbative $\mathrm{RI/MOM}$ renormalization scheme augmented with the Cluster Decomposition Error Reduction (CDER) technique to determine the renormalization constants of $K^\mu$. The results obtained from different components $K^{t,i}$ (with $i$ being the direction of proton momentum or polarization) are consistent with Lorentz covariance within uncertainties. After extrapolating to the continuum limit, $\Delta G$ is found to be $\Delta G = 0.231(17)^{\mathrm{sta.}}(33)^{\mathrm{sym.}}$ at the $\overline{\mathrm{MS}}$ scale ${\mu}^2=10\ \mathrm{GeV}^2$, which constitutes approximately $46(7)\%$ of the proton spin.

In this thesis, we investigate the possibility that dark matter consists of ultra light spin-zero particles with mass $m \sim 10^{-22}\ \text{eV}$. We focus on the role of self-interactions, assuming all other non-gravitational couplings to Standard Model particles are negligible. Such ultra light dark matter (ULDM) is expected to form stable self-gravitating scalar field configurations (solitons), whose properties depend on the particle mass and self-coupling $\lambda$. Using solutions of the Gross-Pitaevskii-Poisson equations, we explore how galactic-scale observations can constrain $m$ and $\lambda$. We show that observational upper limits on the mass enclosed in central galactic regions can probe both attractive and repulsive self-interactions with strengths $\lambda \sim \pm 10^{-96} - 10^{-95}$. We further demonstrate that self-interactions can allow ULDM to describe observed rotation curves as well as satisfy an empirical soliton-halo mass relation in low surface brightness galaxies for $m \sim 10^{-22}\ \text{eV}$ and $\lambda \gtrsim 10^{-90}$. We also study tidal effects in satellite dwarf galaxies and find that attractive self-interactions can extend their lifetimes over cosmological timescales, allowing ULDM to evade recent constraints derived for the non-interacting case. Finally, we explore machine learning based inference of dark matter and baryonic parameters from galaxy rotation curves, showing that neural networks can recover parameters consistent with observations.

Foundation models build an effective representations of data that can be deployed on diverse downstream tasks. Previous research developed the OmniLearned foundation model for collider physics and showed that it could significantly advance discovery potential across collider experiments. In this paper we go beyond collider physics and show that Foundation Models trained on collider data can help improve the prediction of cosmological parameters and to predict halo and galaxy velocities in different datasets from CosmoBench. This is the first time a collider physics model is shown to generalize across scientific fields.

We study Higgs-like inflation in the framework of scalar-torsion gravity, focusing on the general class of $f(T,\phi)$ theories in which gravitation is mediated by torsion rather than curvature. Motivated by the increasing precision of cosmic microwave background and large-scale-structure observations, we examine whether Higgs-like inflation remains compatible with current data in this extended gravitational setting. Working within the slow-roll approximation, we analyze the inflationary dynamics both analytically and numerically. In the dominant-coupling regime we derive closed-form expressions for the scalar spectral index and the tensor-to-scalar ratio as functions of the number of e-folds, and we subsequently relax this assumption by numerically solving the slow-roll equations. Confrontation with the latest constraints from Planck 2018, ACT DR6, DESI DR1, and BICEP/Keck shows that Higgs-like inflation in $f(T,\phi)$ gravity is fully consistent with current bounds, naturally accommodating the preferred shift in the scalar spectral index and leading to distinctive tensor-sector signatures.

We develop an effective theory for biased tracers formulated at the level of the Boltzmann equation, providing a unified description of density and velocity bias. We introduce a general effective collision term in the tracer Boltzmann equation to encode tracer dynamics that are intrinsically different from those of dark matter. This collision operator leads to modified continuity and Euler equations, with source terms reflecting the collision-term physics. At linear order, this framework predicts time- and scale-dependent bias parameters in a self-consistent manner, encompassing peak bias as a special case while clarifying how velocity bias and higher-derivative effects arise. Applying the resulting bias model to redshift-space distortions, we show that the Boltzmann-equation approach reproduces the power spectrum of biased tracers obtained in the Effective Field Theory of Large-Scale Structure up to $k^4$ terms with fewer independent parameters.

Quark-Gluon Plasma (QGP), a strongly interacting state of the early universe, exhibits remarkably fluid-like behavior despite its underlying non-Abelian dynamics. Motivated by these features, we explore time-dependent SU(2) Yang-Mills condensates as non-linear classical background fields to model QGP. We first study quarks in gluon backgrounds and show that quark back-reaction can break the isotropy of the condensate for certain initial conditions. We then compute the one-loop finite-temperature effective action using the background-field method and heat-kernel expansion. The resulting thermodynamic pressure increases with temperature but exhibits an approximately logarithmic dependence. This is expected, as this is the de-confined phase of QGP; it is not exactly an ideal gas due to self-interaction. We also perform lattice calculations for the system to contrast continuum and lattice perspectives. We then add the GW to the thermodynamic QGP model and show that certain frequencies of the GW can induce instabilities in the QGP. Our analysis explores the limitations and role of non-perturbative, time-dependent backgrounds in semi-classical description of Yang-Mills dynamics.

We investigate the $s$-wave $KN$ scattering up to next-to-leading order within a renormalizable framework of covariant chiral effective field theory. Using time-ordered perturbation theory, the scattering amplitude is obtained by treating the leading-order interaction non-perturbatively and including the higher-order corrections perturbatively via the subtractive renormalization. We demonstrate that the non-perturbative treatment is essential, at least at lowest order, in the SU(3) sector of $KN$ scattering. Our NLO study achieves a good description of the empirical $s$-wave phase shifts in the isospin $I=1$ channel. An analysis of the effective range expansion yields a negative effective range, consistent with some partial wave analyses but opposite in sign to earlier phenomenological summaries. For the $I=0$ counterpart, the $KN$ interaction is found to be rather weak and exhibits large uncertainties. Further low-energy $KN$ scattering experiments and lattice QCD simulations are needed to better constrain both $s$-wave channels.

In this work, we compute quantum discord between two causally independent areas in $3+1$ dimensions global de Sitter Axiverse to investigate the signs of quantum entanglement. For this goal, we study a bipartite quantum field theoretic setting driven by an Axiverse that arises from the compactification of Type IIB strings on a Calabi-Yau three fold. We consider a spherical surface that separates the interior and exterior causally unconnected subregions of the spatial slice of the global de Sitter space. The Bunch-Davies state is the most straightforward initial quantum vacuum that may be used for computing purposes. Two observers are introduced, one in an open chart of de Sitter space and the other in a global chart. The observers calculate the quantum discord generated by each detecting a mode. The relationship between an observer in one of the two Rindler charts in flat space and another in a Minkowski chart is comparable to this circumstance. We see that when the curvature of the open chart increases, the state becomes less entangled. Nevertheless, we see that even in the limit when entanglement vanishes, the quantum discord never goes away.

We investigate the oscillation of the Kasner exponent $p_t$ near critical point of the hairy black holes dual to holographic superfluid and reveal a clear inverse periodicity $f(T_c/(T_c-T))$ in a large region below the critical temperature. We first introduce the fourth-power term with a coefficient $\lambda$ to adjust the oscillatory behavior of the Kasner exponent $p_t$ near the critical point. Importantly, we show that the nonlinear coefficient $\lambda$ provides accurate control of this periodicity: a positive $\lambda$ stretches the region, while a negative $\lambda$ compresses it. By contrast, the influence of another coefficient $\tau$ is more concentrated in regions away from the critical point. This work provides a new perspective for understanding the complex dynamical structure inside black holes and extends the actively control from the fourth- and sixth-power term into the black hole interior region.

In the context of the left-right symmetric model, we study the interplay of neutrinoless double beta ($0\nu\beta\beta$) decay, parity-violating Møller scattering, and high-energy colliders, resulting from the Yukawa interaction of the right-handed doubly-charged scalar to electrons, which could evade the severe constraints from charged lepton flavor violation. The $0\nu\beta\beta$ decay amplitude receives additional contributions from right-handed sterile neutrinos. The half-life, calculated in the effective field theory (EFT) framework, allows for an improved description of the contributions involving non-zero mixing between left- and right-handed $W$ bosons and those arising from exchanging a light right-handed neutrino. We find that the relative sensitivities between the low-energy (or high-precision) and high-energy experiments are affected by the left-right mixing. On the other hand, our results show how the interplay of collider and low-energy searches provides a manner to explore regions that are inaccessible to $0\nu\beta\beta$ decay experiments.

In this paper, we investigate the generation of the baryon asymmetry of the universe during the first-order electroweak phase transition. We first study the generation of the helical magnetic field in the framework of the standard model effective field theory with a CP-violating operator. We show that, when the chiral magnetic effect is absent, the helical magnetic field and effective chemical potential cannot generate enough baryon asymmetry when vacuum bubbles collide. We further find that the chiral magnetic effect can amplify the lepton asymmetry in the early universe during the phase transition. We present the baryon asymmetry interpretation requirement on certain parameter spaces of the phase transition and the primordial magnetic field.

We extract the equation of state of hot quark matter from a holographic 2+1 flavor QCD model, which could form the core of a stable compact star. By adding a thin hadron shell, a new type of hybrid star is constructed. With the temperature serving as a parameter, the EoS varies and we obtain stable stars with mass ranging from about 5 to 30 solar masses, and the maximum compactness around 0.2. The I-Love-Q-C relations are further discussed, and compared with the neutron star cases. These compact stars are candidates for black hole mimickers, which could be observed by gravitational waves and distinguished by properties like nonzero tidal Love number and electromagnetic signals.

In a $U(1)_{R-L}$-symmetric supersymmetric model, pseudo-Dirac bino and wino can act like right-handed neutrinos, generating the light neutrino masses through a hybrid Type I + III inverse seesaw mechanism. We investigate such a model to accommodate the baryon asymmetry of the universe together with neutrino masses. A pseudo-Dirac gaugino goes under particle-antiparticle oscillations. Possible $CP$ violation in bino decays, induced by mixing with the neutrinos, can be enhanced in bino--antibino oscillations. Focusing on a long-lived bino, we show that its oscillations and decays can generate the observed baryon asymmetry while the wino is responsible for generating the neutrino masses. This mechanism requires a decoupled mass spectrum with a bino of mass $M_{\tilde{B}}\sim O({\rm TeV})$ and sfermions with mass $M_{\rm sf}\gtrsim 25$ TeV. Furthermore, for the bino to decay out-of-equilibrium before the electroweak sphalerons turn off, the messenger scale needs to be $\Lambda_M \sim O(10^7~ {\rm TeV})$. We discuss the displaced vertex signals at the LHC resulting from such a high messenger scale.

In this work, we investigate the contribution of the annihilation process with initial-state radiation ($e^+ e^- \to \gamma A'$) to the invisible dark photon ($A'$) searches at the electron fixed-target configurations. For illustration, we consider both the disappearing positron track signature at Belle II and the large missing energy search at NA64. When the dark photon has a narrow decay width, the effect of the initial-state radiation to the annihilation process can dominate over its $s$-channel and bremsstrahlung counterparts around $m_{A'} \simeq 60\,\rm{MeV}$ ($m_{A'} \simeq 200\,\rm{MeV}$) for Belle II (NA64), to enhance the corresponding sensitivity on the kinetic mixing parameter $\epsilon$ by a factor of up to approximately 2.7 (1.3). For Belle II, we further perform a multi-bin analysis with the spectrum information to better separate the background and signal channels for significant improvement of the sensitivity.

We investigate a non-instantaneous reheating period in the early Universe, where the inflaton field decays exclusively to right-handed neutrinos (RHNs). The subsequent decay of these RHNs into Standard Model particles not only drives the transition to a radiation-dominated era but also generates the baryon asymmetry of the Universe via leptogenesis. In this typical reheating scenario, gravitational waves (GWs) can be produced during inflaton decay, both through bremsstrahlung and inflaton scattering processes. While GW production via bremsstrahlung dominates near the end of the reheating phase, inflaton scattering leads to a non-negligible GW contribution near the maximum temperature of the Universe. The combined GW spectrum from both decay and scattering processes lies within the sensitivity range of proposed resonant cavity experiments. This framework thus offers a compelling and unified approach to addressing neutrino mass generation, the baryon asymmetry of the Universe via leptogenesis, and probing the dynamics of a non-instantaneous reheating era.

We investigate the structural modifications of heavy quarkonia in the presence of strong magnetic fields using a constituent quark model. By incorporating the effects of spin mixing and quark Landau levels, we employ a nonrelativistic Hamiltonian that captures the essential features of quark dynamics in a magnetic field. The two-body Schrödinger equation is solved using the cylindrical Gaussian expansion method, which respects the cylindrical symmetry induced by a magnetic field. We extract the corresponding light-front wave function (LFWF) densities and analyze their transverse and longitudinal structures, revealing characteristic features such as transverse momentum broadening. While the longitudinal structure is only slightly modified within the nonrelativistic Hamiltonian, we discuss some corrections that can significantly affect its longitudinal structure. Furthermore, we discuss the structure modifications of excited states and find notable changes in the LFWF densities, and state reshuffling near avoided crossings. These results demonstrate the sensitivity of hadron structure to external magnetic fields and help bridge our understanding to relativistic approaches.

$U$-spin symmetry, which reflects the symmetry between the down-type $d$ and $s$ quarks, is a powerful tool for analyzing heavy hadron weak decays. Motivated by recent experimental achievements in the bottom baryon sector, we study the $U$-spin sum rules for bottom baryon decays. The effective Hamiltonian for $b$ quark decay is zero under the $U$-spin lowering operators $U_-^n$, permitting us to derive $U$-spin sum rules involving only the $b\to d$ transition or $b\to s$ transition. Moreover, a new operator, $S_b=U_++rU_3-r^2U_-$, is proposed to generate $U$-spin sum rules involving both the $b\to d$ and $b\to s$ transitions. The proof that the effective Hamiltonian for $b$ quark decay is zero under $U_-^n$ and $S_b$ is presented. The master formulas for generating $U$-spin sum rules for the two-body decays of bottom baryons involving $b\to c\overline cd/s$, $b\to c\overline ud/s$, $b\to u\overline ud/s$, and $b\to u\overline cd/s$ transitions are derived. Numerous $U$-spin sum rules for the two-body decays of bottom baryons are obtained through these master formulas, which provide hints for new decay modes and enable the extraction of dynamical information. As a phenomenological analysis, some branching fractions are predicted according to $U$-spin symmetry. Several rate and decay parameter sum rules beyond the $U$-spin limit are found, providing a more precise test of flavor symmetry in the bottom baryon sector. Moreover, some $CP$ asymmetry relations for $U$-spin conjugate pairs in heavy baryon decays are derived for the first time by taking partial-wave amplitudes into account.

We give an introduction to perturbative Quantum Chromodynamics, focusing on a pedagogical description of concepts and methods to calculate cross sections measured at high energy colliders. After introducing basic concepts that allow for a perturbative expansion, such as factorisation and asymptotic freedom, we introduce loop integrals and the treatment of ultraviolet and infrared divergences in QCD. The definition of jets and event shape observables is also discussed. Finally, we give a brief overview of the current state of the art.

We present the first perturbative QCD calculations of the $\Xi_b \to (\Lambda, \Sigma)$ transition form factors at leading order in $\alpha_s$, which govern the Cabibbo-suppressed semileptonic decays $\Xi_b \to (\Lambda, \Sigma)\ell \nu_\ell$ with $\ell = e, \mu, \tau$. Using these form factors, we evaluate differential and integrated branching fractions and angular observables within the helicity formalism. The branching ratios are predicted to be of order $10^{-4}$ for $\Sigma$ final states and $10^{-5}$ for $\Lambda$ final states, making them accessible to ongoing experiments such as LHCb. Ratios of decay rates between $\tau$ and $e$ channels are also provided, offering new probes of lepton-flavor universality. Lepton-mass effects are found to significantly impact the integrated angular observables. Furthermore, a combined analysis of $b \to u$ and $b \to c$ transitions in $\Xi_b$ decays yields sub-percent precision for the ratios $\mathcal{R}_\ell(\Sigma/\Xi_c)$, enabling an independent determination of $|V_{ub}/V_{cb}|$ once the relevant decay-rate measurements become available.

Hadronization, a nonperturbative process, cannot be calculated from first principles. It can be investigated either by using phenomenological models or by examining the behavior of produced hadrons or through fragmentation functions. These fragmentation functions are nonperturbative quantities whose determination relies entirely on experimental data. However, higher-twist fragmentation functions present significant challenges for their determination due to power suppression. In this paper, we propose an asymmetry to study twist-3 fragmentation functions. This asymmetry is defined as the transverse momentum asymmetry of the fragmenting quark and/or the produced jet with respect to the observed hadron direction within the semi-inclusive electron positron annihilation process. As a twist-3 effect, this asymmetry is sensitive to the distribution of the jet relative to the produced hadron direction during hadronization. Furthermore, it is closely related to twist-3 transverse momentum dependent fragmentation functions and provides a set of measurable quantities for their determination.

As a key property of hadrons, the total width is quite difficult to obtain in theory due to the extreme complexity of the strong and electroweak interactions. In this work, a deep neural network model with the Transformer architecture is built to precisely predict meson widths in the range of $10^{-14} \sim 625$ MeV based on meson quantum numbers and masses. The relative errors of the predictions are $0.12\%, 2.0\%,$ and $0.54\%$ in the training set, the test set, and all the data, respectively. We present the predicted meson width spectra for the currently discovered states and some theoretically predicted ones. The model is also used as a probe to study the quantum numbers and inner structures for some undetermined states including the exotic states. Notably, this data-driven model is investigated to spontaneously exhibit good charge conjugation symmetry and approximate isospin symmetry consistent with physical principles. The results indicate that the deep neural network can serve as an independent complementary research paradigm to describe and explore the hadron structures and the complicated interactions in particle physics alongside the traditional experimental measurements, theoretical calculations, and lattice simulations.

We consider models of chaotic inflation driven by the real parts of a conjugate pair of Higgs superfields involved in the spontaneous breaking of a grand unification symmetry at a scale assuming its value within MSSM. We combine a superpotential, which is uniquely determined by applying a continuous R symmetry, with two fractional shift-symmetric Kaehler potentials introducing two free parameters (p,N). The inflationary observables provide an excellent match to the recent ACT data for 1.355<=p<=6.7 and 6x10^-5<= N<=0.7. The attainment of inflation allows for subplanckian inflaton values and possibly detectable primordial gravitational waves with (p,N) values of order unity. A solution to the mu problem of MSSM and baryogenesis via non-thermal leptogenesis can be also accommodated by embedding the model into a B-L extension of MSSM.

Flavor-changing neutral current (FCNC) processes play a prominent role in the search for physics beyond the Standard Model (SM) due to their sensitivity to new physics at the TeV scale. Meson-antimeson transitions and rare meson decays provide stringent constraints on new physics through precision measurements of observables such as mass differences, CP asymmetries, and branching ratios. Extensions of the SM based on the $\text{SU}(3)_C \times \text{SU}(3)_L \times \text{U}(1)_N$ gauge group offer a compelling framework for flavor physics, as FCNC processes emerge inexorably at tree level due to the non-universal transformations of the quark families. Among its various realizations, the version incorporating right-handed neutrinos (331RHN) is the most phenomenologically viable. This review synthesizes three decades of theoretical developments in FCNC phenomenology within the 331RHN model, from early $Z^\prime$-dominated studies to the recent recognition of the decisive role played by the SM-like Higgs boson and the identification of the alignment limit. We demonstrate that viable parameter space spans orders of magnitude, from $m_{Z^\prime} \sim$ a few hundred GeV to $\sim 100$ TeV, depending critically on quark mixing parametrizations and scalar alignment configurations, with significant implications for experimental searches at current and future colliders.

We investigate the production of hyperons, charmed baryons, and potential hadronic molecular states in neutrino-proton $(\bar{\nu}_\mu p)$ reaction, a process characterized by a particularly clean final state. Employing effective Lagrangians, chiral perturbation theory, and a hadronic molecular model, we perform theoretical calculations for several relevant channels, including those leading to the formation of the hadronic molecular candidate $(\bar{D}N)$ and $(\bar{D}\Sigma)$. Our results indicate that future neutrino facilities could serve as a complementary platform for exploring exotic baryonic states and provide valuable insights into the dynamics of strong interactions in the strange and charm sectors.

Core-collapse supernovae serve as powerful probes of light, weakly coupled particles, such as dark photons. The conventional SN1987A cooling bound constrains the dark photon mass-mixing parameter space by requiring that the luminosity from the proto-neutron star core not exceed the observed neutrino emission. In this work, we revisit these limits by including the effect of dark matter (DM) captured inside the progenitor star before collapse. The trapped DM acts as an additional scattering target for dark photons, modifying their free-streaming length and, consequently, the supernova cooling rate. We perform a self-consistent analysis for both annihilating and asymmetric DM scenarios, incorporating light-mediator effects in the capture rate calculation. For annihilating DM, the equilibrium density remains too small to affect the bounds significantly. In contrast, asymmetric DM can accumulate to large densities, leading to the formation of a "dark photosphere" that suppresses the dark-photon luminosity and reopens previously excluded regions of parameter space. Our results emphasise the importance of accounting for astrophysical DM populations when deriving stellar-cooling constraints on dark sectors.

The masses of exotic quantum-number $1^{-+}$ compact tetraquark states are calculated in a constituent quark model, where a Cornell-like potential is employed as the central potential, spin-spin and spin-orbit coupling derived from the Breit-Fermi interaction are treated as hyperfine corrections, and model parameters are taken from previous works. The ground state $1^{-+}$ P-wave tetraquarks are predicted at 1.9, 4.2, and 6.6~GeV for the light, charmonium-like, and fully-charm sectors, respectively. The decay width ratios of $1^{-+}$ tetraquark states are calculated for two-body strong decay channels within the rearrangement mechanism, including $\omega h_1$ and $\eta f_1$ for isospin $I=0$ light tetraquarks, $\rho h_1$ and $\pi f_1$ for isospin $I=1$ light tetraquarks, $\pi/\eta+\chi_{c1}$ and $\rho/\omega + h_c$ for charmonium-like tetraquarks, and $\eta_c \chi_{c1}$ and $J/\psi h_c$ for fully-charm tetraquarks. The theoretical results are compared with the observed exotic $1^{-+}$ states, and promising search channels for $1^{-+}$ tetraquarks are discussed. The work suggests that $\eta_1(1855)$ is unlikely to be a compact tetraquark state.

We compute all the planar three-loop master integrals relevant for the leading colour N3LO QCD corrections to the production of two massive or off-shell vector bosons at hadron colliders. These integrals are organised into nine four-point integral families with massless internal propagators and two external massive legs. For each family, we construct a basis of pure master integrals and we reconstruct the corresponding canonical differential equations using finite field techniques. We evaluate the master integrals by solving the differential equations using generalised power series expansions.

Neutrino masses remain a significant unsolved problem in physics and their nonzero value proves the Standard Model is incomplete. Currently, the values of the three masses only have upper limits from cosmology and experiments like KATRIN. This paper shows that the SN 1987A neutrino data can remarkably yield values for the three neutrino masses, and not merely upper limits. Although this seemingly preposterous idea was suggested a dozen years ago by the author, here it is demonstrated in a much more convincing manner with many new elements, including a stronger statistical treatment, and a thorough explanation of why the method used to find the three masses from supernova SN 1987A neutrino data really works. The key to finding the three neutrino masses is realizing why three normally accepted assumptions are unjustified, The three rejected assumptions are:(a) the 5-hr early LSD (Mont Blanc) neutrinos are unrelated to SN 1987A, (b) any neutrino masses $m_k>1 eV/c^2$ cannot be reconciled with upper limits on the ``effective mass" from KATRIN and other data, and (c) the spread in neutrino emission times from SN 1987A data is too great for the method to work. A particularly crucial piece of evidence supporting the claim made in the paper's title involves a recent negative KATRIN result finding an absence of sterile neutrinos.

Generalized Parton Distributions (GPDs) have emerged as a powerful framework for exploring the internal structure of hadrons in terms of their partonic constituents. Over the past three decades, the field has witnessed significant theoretical and experimental advancements. The interpretation of GPDs in impact parameter space offers a vivid three-dimensional visualization of hadron structure, correlating longitudinal momentum and transverse spatial distributions, thereby enabling tomographic imaging of hadrons. Furthermore, the link between GPDs and the matrix elements of the QCD energy-momentum tensor provides access to fundamental properties of hadrons, including spin decomposition and internal pressure distributions. Notably, recent analyses of Deeply Virtual Compton Scattering (DVCS) data have enabled the empirical extraction of the quark pressure profile inside the proton. This white paper presents an overview of recent developments in GPD theory and phenomenology, as well as progress in lattice QCD studies. It outlines the prospects for advancing our understanding of hadron structure through the next generation of dedicated experiments, including the extension of the Jefferson Lab 12~GeV program (and its potential 22~GeV upgrade), J-PARC, COMPASS/AMBER, LHC ultra-peripheral collisions, and the future electron-ion colliders EIC and EicC.

We revisit the proposal of Craig and Sutherland that Anderson localization in a disordered fermion theory space can generate small neutrino masses from TeV scale physics \citecraig2018exponential}. Building on this idea, we ask a broader question: can randomness in fermion mass parameters also give rise to nonanarchical neutrino mixing angles, and how does the answer depend on the geometry of the mass graph? To explore this, we analyse three representative geometries a nearest neighbour chain, a fully connected non local model, and the Petersen graph in both Dirac and Majorana neutrino realisations. In the regime of strong diagonal disorder, all geometries display robust localization and naturally generate the observed neutrino mass scale, with the corresponding flavour mixing angles reflecting the random localization centres and thus taking an anarchical form. In the regime of weak disorder, where localization is milder, and eigenmodes can exhibit quasidegeneracies, light neutrino masses can emerge through GIM-mechanismlike cancellations among the heavy states. The weak disorder with geometry dependent weak localization constitutes a distinct pathway to structured mixings within disordered theory spaces. Overall, our results delineate the regimes in which disorder driven mechanisms produce hierarchical masses and identify the conditions under which structured flavour mixing can arise.

In this paper we present a realization of dark dimension. We consider the 5D standard model coupling to gravity with one dimension compactified on an orbifold, which is seen as dark dimension of size R. We stabilize the radion by casimir effect wrapping around compact dimension and recover the neutrino mass and 4D cosmological constant with the observed value. Orbifold can lead to a natural resolution of chirality problem in 5D at low energy, which we briefly discussed in the paper. Although we found that the radion mass is too light to survive under solar system tests of GR, several screening mechanisms might give us a solution, for example, Chameleon mechanism.

We generalize the equivalence between off-equilibrium state and gravitational perturbation of equilibrium state from dynamics of macroscopic quantities to that of microscopic particles. We also generalize the equivalence to incorporate off-equilibrium state with vorticity by torsional perturbation to equilibrium state. The equivalence is achieved by mapping kinetic theories of spinless and spinning particles in torsional curved space to flat space through suitable choice of inertial frame that eliminates geodesic forces on particles. The equivalence has been shown for hydrodynamic and elastic regimes. In the latter case, we predict spin polarization induced by time-variation of shear strain in elastic materials. We also provide an order-of-magnitude estimate for the polarization in Dirac semi-metal.

In this paper, we employ the gauge/gravity duality to study jet quenching (JQ) phenomena in the quark-gluon plasma. For this purpose, we implement holographic QCD models constructed from an Einstein-Maxwell-dilaton gravity at finite temperature and finite chemical potential for light and heavy quarks. The models capture both the confinement and deconfinement phases of QCD and the first-order phase transitions. We calculate the JQ parameter in different models and compare them with the experimental data obtained in heavy-ions studies. In particular, we investigate how JQ, as a function of temperature $T$, chemical potential $\mu$, and magnetic field $c_B$, serves as a probe for identifying first-order phase transitions within the $(T,\mu,c_B)$ parameter space of holographic QCD. Particular attention is paid to the dependence of JQ on the parameter $\nu$, which characterizes longitudinal versus transverse anisotropy relative to the heavy-ion collision axis. By analyzing the dependence of the JQ parameters on these thermodynamic variables, we map critical regions associated with phase boundaries. We compare our findings to earlier studies of the running coupling constant's behavior within the gauge-gravity duality framework. This approach provides new insights into the interplay between non-perturbative dynamics and phase structure in strongly coupled systems.

We explore the idea that quantum vacuum energy $\rho_{\rm vac} $ is at the origin of Gravity. We formulate a gravitational version of the electromagnetic Casimir effect, and provide an argument for how gravity can arise from $\rho_{\rm vac} $ by showing how Einstein's field equations emerge in the form of Friedmann's equations. This leads to the idea that Newton's constant $G_N$ is environmental, namely it depends on the total mass-energy of the Universe $M_\infty $ and its size $R_\infty $, with $G_N = c^2 R_\infty /2 M_\infty$. This leads to a new interpretation of the Gibbons-Hawking entropy of de Sitter space, and also the Bekenstein-Hawking entropy for black holes, wherein the quantum information bits are quantized massless particles at the horizon with wavelength $\lambda = 2 \pi R_\infty$. We assume a recently proposed formula for $\rho_{\rm vac} \sim m_z^4/\mathfrak{g}$, where $m_z$ is the mass of the lightest particle, and $\mathfrak{g}$ is a marginally irrelevant coupling. This leads to an effective, induced RG flow for Newton's constant $G_N$ as a function of an energy scale, which indicates that $G_N$ decreases at higher energies until it reaches a Landau pole at a minimal value of the cosmological scale factor $a(t) > a_{\rm min}$, thus avoiding the usual geometric singularity at $a=0$. The solution to the scale factor satisfies an interesting symmetry between the far past and far future due to $a(t) = a(-t + 2 t_{\rm min})$, where $a(t_{\rm min}) = a_{\rm min}$. We propose that this energy scale dependent $G_N$ can explain the Hubble tension and we thereby constrain the coupling constant $\mathfrak{g}$ and its renormalization group parameters. For the $\Lambda{\rm CDM}$ model we estimate $a_{\rm min} \approx e^{-1/\hat{b} }$ where $\hat{b} \approx 0.02$ based on the Hubble tension data.

Primordial black holes (PBHs) formed from the collapse of density fluctuations provide a unique window into the physics of the early Universe. Their evaporation through Hawking radiation around the epoch of Big Bang nucleosynthesis (BBN) can leave measurable imprints on the primordial light-element abundances. In this work, we analyze in detail the effects of PBHs evaporating before BBN, with various intermediate steps understood analytically, and obtain the BBN constraint on PBHs within a transparent and reproducible framework. We find that, to produce observable effects on BBN, the PBH mass must exceed $10^{9}$ g, a threshold higher than that reported in some earlier studies. Slightly above $10^{9}$ g, the BBN sensitivity rapidly increases with the mass and then decreases, with the turning point occurring at $2\times10^{9}$ g. For PBHs in the mass range $[10^{9},\ 10^{10}]$ g, current measurements of BBN observables set an upper bound on the initial mass fraction parameter $\beta$ ranging from $10^{-17}$ to $10^{-19}$. To facilitate future improvements, we make our code publicly available, enabling straightforward incorporation of updated nuclear reaction rates, particle-physics inputs, and cosmological data.

We present limits on spin-independent inelastic weakly interacting massive particles (WIMP)-nucleus scattering using the 737.1 kg$\cdot$day dataset from the CDEX-1B experiment. Expected nuclear recoil spectra for various inelastic WIMP masses $m_\chi$ and mass splittings $\delta$ are calculated under the standard halo model. An accurate background model of CDEX-1B is constructed by simulating all major background sources. The model parameters are then determined through maximum likelihood estimation and Markov chain Monte Carlo fitting. The resulting 90\% confidence level upper limits on the WIMP-nucleon cross section $\sigma_{\mathrm{n}}$ exclude certain DAMA/LIBRA allowed regions: the $\chi^2 < 4$ regions for $\delta < 30$ keV at $m_\chi = 250$ GeV and the $\chi^2 < 9$ region for $\delta < 50$ keV at $m_\chi = 500$ GeV. The method is applicable to other inelastic dark matter scenarios, and the upcoming CDEX-50 experiment is expected to improve sensitivity by four orders of magnitude.

The stellar compactness, that is, the dimensionless ratio between the mass and radius of a compact star, $\mathcal{C} := M/R$, plays a fundamental role in characterising the gravitational and nuclear-physics aspects of neutron stars. Yet, because the compactness depends sensitively on the unknown equation of state (EOS) of nuclear matter, the simple question: ``how compact can a neutron star be?'' remains unanswered. To address this question, we adopt a statistical approach and consider a large number of parameterised EOSs that satisfy all known constraints from nuclear theory, perturbative Quantum Chromodynamics (QCD), and astrophysical observations. Next, we conjecture that, for any given EOS, the maximum compactness is attained by the star with the maximum mass of the sequence of nonrotating configurations. While we can prove this conjecture for a rather large class of solutions, its general proof is still lacking. However, the evidence from all of the EOSs considered strongly indicates that it is true in general. Exploiting the conjecture, we can concentrate on the compactness of the maximum-mass stars and show that an upper limit appears for the maximum compactness and is given by $\mathcal{C}_{\rm max} = 1/3$. Importantly, this upper limit is essentially independent of the stellar mass and a direct consequence of perturbative-QCD constraints.

In our alternative theory, built around the coincidence of experimental and theoretical data, three "free" parameters -- the magnetic field in the tachocline of the order of ~10^7 G (see Fig.(A.1) and Eq.(A17) in V. D. Rusov et al. (2021)), the axion mass ma ~3.2*10^{-2} eV (see Eq. (11) in V. D. Rusov et al. (2021)), and the asymmetric dark matter (ADM) in the Universe with mADM ~5 GeV ((see V. D. Rusov et al. (2021); A. C. Vincent et al. (2016)) -- give a complete solution to the problem of the theory of magnetic flux tubes in strong fields with 11-year variations of axion-origin photons, which are caused by and anticorrelated to the 11-year variations in density of ADM, gravitationally captured on the Sun.