High Energy Physics - Phenomenology

We propose metallic carbon nanotubes (CNTs) as a one-dimensional plasmon target for light dark matter (DM) direct detection. Unlike conventional gapless electronic targets, where DM primarily excites electron-hole pairs, the low-energy charge response of a metallic CNT is carried by a collective Luttinger-liquid mode. We compute the projected sensitivity for DM-electron scattering through heavy and light mediators, using benchmark thresholds motivated by quantum-capacitance-detector-like and superconducting-quasiparticle-amplifying-transmon-like readout. For an accumulated nanotube length $L_{\text{CNT}}=10^8{\rm m}$, corresponding to milligram-scale single-wall CNT targets, we find competitive reach in the keV--MeV mass range. In the light-mediator case, the projected sensitivity can probe the cosmologically motivated freeze-in benchmark at keV masses. We also show that the one-dimensional geometry of aligned CNTs induces sidereal-day modulation, providing a handle for distinguishing a DM signal from approximately time-independent sensor backgrounds. These results establish one-dimensional collective modes as a new target class for sub-MeV DM detection. Existing progress in scalable CNT synthesis and superconducting quasiparticle sensing provides a promising experimental foundation, while realizing the proposed detector will require dedicated development of CNT--superconductor coupling and plasmon-to-quasiparticle conversion.

We investigate the sensitivity of a same-sign $\mu^+\mu^+$ collider to doubly charged scalars in the Type-II seesaw framework, focusing on the regime in which the doubly charged scalar decays dominantly into same-sign $W$-boson pairs. Motivated by the $\mu$TRISTAN proposal, for a benchmark we consider a degenerate triplet spectrum at a center-of-mass energy of $2~{\rm TeV}$ and an integrated luminosity of $1~{\rm ab}^{-1}$. The signal process is studied in the fully hadronic $W$-decay mode, leading to a characteristic $\mu^+\mu^+ + 8j$ final state. We develop a cut-based analysis based on high jet multiplicity and global hadronic $W$ reconstruction, and then improve its sensitivity with a multivariate strategy exploiting reconstructed $W$ observables, global event kinematics, multi-boson variables and spectator-muon information. The best-performing setup reaches a $2\sigma$ sensitivity level for doubly charged scalar masses up to $425-430~{\rm GeV}$, extending the cut-based reach by a few tens of GeV. This indicates an improvement over the current LHC coverage, while also providing an independent probe based on a qualitatively different production mode and collider environment.

We show that muon bremsstrahlung provides a new production mechanism for light new physics at accelerator neutrino experiments. The intense, highly collimated muon beam produced alongside the neutrino beam in meson decays provides a powerful source for the bremsstrahlung production of new physics when it impinges on the beam dump at these facilities. As a benchmark scenario, we consider a muonphilic scalar coupled to Heavy Neutral Leptons (HNLs) and show that muon bremsstrahlung enables the production of HNLs with masses beyond the kinematic reach of meson decays. Using this new production mechanism and focusing on HNL mixing with tau neutrinos, we find that ongoing (upcoming) short-baseline experiments like SBND (DUNE Near Detector) can probe previously unexplored parameter space for HNL masses up to $\mathcal{O}(1)~\mathrm{GeV}$ through their decay into pions, $\mu^+\mu^-$, and $e^+e^-$ final states at the detector. The resulting signals exhibit distinctive kinematics, allowing efficient discrimination from neutrino-induced Standard Model backgrounds. Our results demonstrate that the muon bremsstrahlung mechanism substantially extends the discovery potential of accelerator neutrino experiments for HNLs and other dark sector particles.

We demonstrate that polarized strange quarks undergo Larmor precession in the intense magnetic field produced in non-central heavy-ion collisions and as a possible source of charge-odd hyperon polarization. Strange and antistrange quarks carry opposite electric charges and therefore acquire opposite precession phases. This opposite spin rotation mixes the transverse and longitudinal polarization components, yielding measurable polarization splittings between $\Lambda$ and $\bar{\Lambda}$ hyperons. For the magnetic-field evolution scenarios, the predicted splittings reach the sub-percent level and are within the experimentally accessible range at RHIC and the LHC energies. These charge-resolved hyperon polarization observables provide a direct probe of magnetic-field-driven spin dynamics of deconfined QCD matter at ultra-relativistic heavy-ion collisions.

Direct evidence for collective neutrino oscillations in core-collapse supernovae remains elusive. We show that this quantum phenomenon leaves a footprint on the abundance pattern of proton-rich nuclides in the solar system. Modeling the $\nu p$-process using a $20\,M_\odot$ progenitor, we map out the dependence of the total yields on the starting radius of the oscillations, self-consistently coupling hydrodynamics and nucleosynthesis. The oscillations boost key $p$-nuclides ($^{92,94}\text{Mo}$, $^{96,98}\text{Ru}$) and long-lived $^{92}\text{Nb}$ by up to two orders of magnitude, bringing their abundances into agreement with the observations. The best match is found when oscillations commence within $10\text{ km}$ of the proto-neutron star surface, indicating fast collective oscillations.

The collapse of false-vacuum domains during first-order phase transitions in the early Universe may lead to primordial black hole (PBH) formation whose signatures form a multimessenger complement to gravitational wave (GW) production. We focus on PBH formation through the gravitational collapse of false-vacuum domains, described using a junction condition formalism. This formalism develops the Schwarzschild collapse criterion dynamically, avoiding the usage of critical overdensity thresholds in a post-inflationary Universe, and is driven solely by the vacuum energy enclosed within shrinking false-vacuum domains without the assistance of particle or domain wall interactions in the false vacuum. We study the parameter space of phase transitions and identify regions producing observable GWs, observable PBHs, or both simultaneously. We investigate this phenomenology in polynomial and classically conformal scalar field potentials as model benchmarks. We find that the scalar fields with vacuum expectation values in the range of 1-100 MeV have the largest model parameter space available for these multi-messenger signals, which are testable with upcoming GW observatories, searches for Hawking radiation, and gravitational lensing surveys.

Modern jet taggers based on graph and transformer networks deliver state-of-the-art performance but are expensive to train and difficult to share across experiments. Knowledge distillation can in principle achieve model compression, but it rests on the assumption that the teacher model acts as a perfect tagger. This assumption fails to hold at high-purity working points, where the teacher itself exhibits a jet prediction error rate of approximately $10\%$ to $30\%$. We introduce JetCoRD, the first cross-experiment distillation in HEP: an 82 k-parameter unified student distilling jointly from ATLAS GN2 (5 M params, 3 classes) and CMS ParT (2 M params, 10 classes). The central innovation is a single per-sample reliability signal $r_i$ that simultaneously weights the distillation loss, controls prototype-based teacher repair, and anchors the inference-time gate $g_i$ that mixes teacher and student logits. With only 82 k trainable parameters (1.2% of the combined 7 M teacher parameters), the student matches both teachers in overall accuracy and exceeds them at physics-actionable working points: $+4.3\%$ on $b$-vs-$c$ at $\varepsilon=0.77$, $+1.5\%$ on $c$-vs-$u$ at $\varepsilon=0.30$, $+1.6\%$ on $T\!\to\!bqq$ at $\varepsilon=0.5$ and $+1.4\%$ on $H\!\to\!bb$ at $\varepsilon=0.5$. The reliability-coupled design is novel in HEP distillation and applicable wherever an imperfectly calibrated teacher must be compressed.

Although hidden-photon dark matter with masses above $10^{-4}\,\mathrm{eV}$ is well motivated by inflationary production, it remains largely unexplored by terrestrial experiments. Through kinetic mixing, hidden photons induce a weak oscillating electric field above $10\,\mathrm{GHz}$. We propose to amplify this signal using a compact high-frequency distributed cavity and detect it with chip-scale Rydberg-atom superheterodyne spectroscopy. Combining resonant enhancement, large dipole moments of Rydberg atoms, and long-term stable integration, this approach can probe hidden-photon dark matter in the mass range $5 \times 10^{-5}\text{--}7\times 10^{-4}\,\mathrm{eV}$ with sensitivities $3$--$4$ orders of magnitude beyond existing limits.

A nonequilibrium Green's function approach to heavy-quark transport is discussed within the framework of the Kadanoff-Baym equation. One- and two-loop self-energy diagrams with hard-thermal-loop resummed propagators are calculated in the real-time formalism. Under the quasiparticle approximation, the kinetic equation reduces to the Boltzmann equation that accounts for elastic scattering and medium-induced gluon emission from a single scattering. Numerical studies suggest that off-shell and memory effects in quark-gluon plasmas influence heavy-quark dynamics, particularly near the critical temperature.

Loops of portal matter (PM) fields, carrying both Standard Model (SM) and dark charges, can generate the necessary kinetic mixing (KM) between the ordinary and dark photons (DP) in vector portal scenarios thus allowing for interactions between visible and dark sector fields. Here we show that the field content of a previously considered model based on a partial $E_6$-like UV-completion of such setups can generate light Dirac neutrino masses in the interesting range, $\sim 0.05$ eV, at the one-loop level similar to what happens in scotogenic dark matter (DM) scenarios. While general $E_6-$like PM scenarios have been shown to be easily probed at colliders, such as the HL-LHC, uniquely testing this specific subclass of these setups in a direct fashion is found to be somewhat more challenging.

This is a review on gluon saturation. Sec. 1 gives a general introduction to the subject while Sec. 2 has a brief discussion of quark saturation. Sec. 3 covers gluon saturation in a semiclassical limit and the much more general context of QCD evolution. Surprisingly gluon occupancies in a high energy hadron can become arbitrarily large, much larger than $1/\alpha$. Sudakov effects are introduced in Sec. 4 and reduce the maximum gluon occupancies to less than or equal to $(1/\alpha)^{3/2}$ in both fixed coupling and running coupling QCD. In Sec. 5 the role of saturation in coherent states in QCD is reviewed as well as brief discussions on nuclear shadowing, heavy ion collisions and Drell-Yan like processes are given.

In the present work, we propose to investigate the productions of $P_{c}(4312)$, $P_{c}(4440)$, and $P_{c}(4457)$ in the $e^{+} e^{-} \rightarrow p \bar{p} J/\psi$ process. By using an effective Lagrangian approach, we estimate the cross section for the processes under consideration. For the $e^{+} e^{-} \rightarrow \bar{p} P_{c}(4312)$, $e^{+} e^{-} \rightarrow \bar{p} P_{c}(4440)$, and $e^{+} e^{-} \rightarrow \bar{p} P_{c}(4457)$ processes, the cross sections are evaluated to be ($46.6^{+88.4}_{-34.5}$) fb, ($57.4^{+109}_{-42.5}$) fb, and ($55.1^{+105}_{-40.8}$) fb at $\sqrt{s}=6$ GeV, respectively, where the central values are estimated with $\Lambda_{r}=3.0$ GeV, and the uncertainties are resulted from the variations of $\Lambda_{r}$ from 2.5 to 3.5 GeV. Considering that the $P_{c}$ states can decay into $J/\psi p$, we estimate the cross sections for $e^{+} e^{-} \rightarrow p \bar{p} J/\psi$ and the differential cross sections depending on the $J/\psi p$ invariant mass. At $\sqrt{s}=6$ GeV, the cross sections for $e^{+} e^{-} \rightarrow p \bar{p} J/\psi$ are estimated to be ($34.6^{+68.0}_{-26.0}$) fb. Moreover, our estimations indicate that the cross section resulted from the $P_{c}(4457)$ and $\bar{P}_{c}(4457)$ intermediate states is dominant. In the $J/\psi p$ invariant mass spectrum, a splitting signal can be observed around 4.45 GeV, with the two peaks corresponding to $P_{c}(4440)$ and $P_{c}(4457)$.

We identify the smallest discrete flavor symmetry and minimal field content that can simultaneously account for neutrino masses and the dark sector in the context of the discrete dark matter. Minimality is achieved with a $D_4$ symmetry by adding three right-handed neutrinos and three scalar doublets. Within this framework, tree-level and one-loop contributions yield the observed solar--atmospheric mass splitings as well as the observed neutrino mixings. Furthermore, by including CP-violating phases, the model successfully accommodates both normal and inverted ordering. Spontaneous $D_4$ breaking leaves a residual $\mathbb{Z}_2$ symmetry that stabilizes the dark matter candidate, with a predicted mass within the $50$--$200$ GeV range, consistent with LUX-ZEPLIN limits.

In this work we demonstrate that a single transformer-based generative model can capture Standard Model structure spanning five decades of invariant mass, from the sub-GeV regime to the TeV continuum, a range that no single Monte Carlo sample covers. To achieve this we design \textsc{ShellFlow}, a Riemannian conditional flow matching model that, given the recorded event composition, generates each particle on its on-shell manifold. Its only physics priors are the on-shell condition and the invariant-mass formula. The model is trained on $\sim 10^{9}$ real $pp$ collision events from the ATLAS Open Data 13~TeV release and told nothing else. From a single training run, the model learns to reproduce all of the following: intra-particle kinematics, the dilepton resonances ($J/\psi$, $\Upsilon$, $Z$) at their PDG positions, the leptonic Weinberg angle, the $W$ and top-quark masses, and inter-particle correlations that enter no training objective. A substantial fraction of the Standard Model is thus learnable directly from recorded collision data.

Using the stress-energy tensor response functions obtained in the Anderson-Witting model of kinetic theory with non-zero mass, we verify that these response functions satisfy the required analytic conditions and are fully consistent with the recently derived Kubo formulas in Ref.[1].

Geometric scaling was conjectured and observed at the ISR more than 50 years ago. We argue that it still holds at the LHC. We show that the dip-bump structures of the differential elastic cross-sections exhibit a remarkable regularity, namely that the ratio of the bump to dip positions is constant from 23 GeV to 13 TeV. Using crossing symmetry, analicity and the optical theorem, we identify the imaginary and real parts of the scattering amplitude. This allows us to compute the $\rho$ parameter and the ratio of the bump to dip values of the differential $pp$ cross-section. Finally, we discuss the energy dependence of the total elastic cross-section as compared to the total cross-section, and the violation of geometrical scaling outside the dip-bump region at the LHC.

Large-scale structure provides a powerful probe of inflationary physics through primordial non-Gaussianity (PNG): the galaxy power spectrum depends on local PNG through scale-dependent bias, while the galaxy bispectrum depends sensitively on both equilateral and orthogonal PNG. In this paper, we study whether galaxy surveys can also probe folded PNG, whose shape is enhanced near $k_1+k_2-k_3\rightarrow0$. We consider three inflationary models with folded PNG, including excited initial states, imaginary speeds of sound, and dissipative inflation. These models fall into two classes: cutoff-regulated cases in which the folded-enhanced region has a power-law width, and dissipation-regulated cases in which the enhanced region is exponentially narrow. We develop a numerical pipeline for computing the corresponding PNG contributions to the redshift-space galaxy power spectrum multipoles and bispectrum monopole within the EFTofLSS. Using Fisher forecasts, we show that most of the constraining power on folded PNG comes from the galaxy bispectrum. For the cutoff-regulated models, nuisance parameter marginalization causes only a mild loss of information at large folded enhancement, but finite Fourier-space binning degrades constraints once the folded region becomes narrower than the bin width. For the dissipation-regulated models, the exponentially narrow folded enhancement is hard to resolve and the observable signal instead comes from the broader support of the template, leading to weaker binning dependence but larger overlap with the equilateral template. Our results show that folded PNG is a distinctive and promising target for galaxy bispectrum analyses, and the detectability depends on the width and morphology of the folded enhancement. The numerical pipeline developed in this work is general and can be used to study a wide class of non-separable primordial bispectra.

We propose a hybrid realization of Starobinsky inflation in which the inflationary epoch ends through vacuum decay. The model consists of an effective two-field system with a metastable Starobinsky branch shifted with respect to the true one. During the observable stage, the inflaton slow-rolls along the false branch, until a first-order phase transition in an orthogonal direction connects it to the true branch and ends inflation abruptly. This old-inflation-like exit skips the last part of the would-be Starobinsky trajectory. As a result, the Cosmic Microwave Background pivot scale exits the Hubble radius further from the minimum of the false branch than in ordinary Starobinsky inflation, raising the scalar spectral tilt $n_s$ while preserving the characteristic small tensor-to-scalar ratio. This provides a simple way of moving Starobinsky inflation towards the high-$n_s$ region favoured by recent ACT-related combinations. The same vacuum transition leaves a stochastic gravitational-wave relic whose peak frequency is controlled by the tunnelling timescale and the subsequent reheating history.

The path optimization method is applied to the Stephanov model and the chiral random matrix model, both of which share several properties with QCD, to mitigate the sign problem caused by the fermion determinant. The Stephanov model serves as a prototypical model of finite-density QCD, while the chiral random matrix model represents an ideal system featuring the Silver Blaze phenomenon. We show that the path optimization successfully improves the average phase factor in the Stephanov model at high chemical potential, reproducing the analytical results with reduced statistical errors. However, it fails to improve the average phase factor in the Stephanov model at low chemical potential, as well as in the chiral random matrix model. This tendency in the phase factor behavior seems to be closely related to the global sign problem.

Magnetars are neutron stars with ultra-strong magnetic fields ($B \sim 10^{14}$-$10^{15}$ G) and are promising candidates for high-energy particle acceleration. We present a multiwavelength analysis of the region surrounding CXOU J171405.7-381031, a magnetar associated with the supernova remnant (SNR) CTB 37B. The broadband spectral energy distribution spanning radio to TeV energies is modeled using leptonic and lepto-hadronic scenarios, with particle populations constrained using Markov Chain Monte Carlo techniques. Within an SNR framework, both scenarios provide acceptable descriptions of the gamma-ray data. The purely leptonic model reproduces the overall spectral shape but slightly underestimates the highest-energy flux measured by H.E.S.S., whereas a lepto-hadronic interpretation offers an improved description above $\sim 10$ TeV, with inverse-Compton scattering dominating the GeV emission and neutral-pion decay contributing at the highest energies. The required proton energy ($W_{\rm p} \gtrsim 10^{51}$ erg) can be substantially reduced if the remnant interacts with a dense ambient medium. A magnetar wind nebula scenario can reproduce the broadband spectrum but is strongly disfavored by the observed source morphology. Simulated Cherenkov Telescope Array Observatory (CTAO) observations indicate that exposures of $\sim 50$ h will constrain the proton cut-off energy, enabling a decisive test of hadronic emission in this region.

Unlike the gravitational waves classically generated by moving macroscopic masses, the diffuse backgrounds of gravitons originate most likely from zero-point fluctuations of the gravitational field amplified by the evolution of the space-time curvature. The resulting entangled states lead to specific second-order correlation effects that could be eventually detected. For a quantitative analysis of this empirical expectation we scrutinize the interactions between the cosmic gravitons and the fundamental mode of a quantized electromagnetic field confined inside a closed optical resonator with perfectly-reflecting walls. We show that the Hanbury-Brown Twiss correlations of the photons are insensitive to the degrees of second-order coherence of the gravitons even barring for the exceedingly small couplings of the problem. Since the degree of second-order coherence of the photons does not reflect the correlation properties of the gravitons, the statistical properties of the gravitons (and their super-Poissonian statistics) cannot be inferred, even in principle, from the intensity correlations of the cavity modes.

We describe recent advances in our understanding of the analytic structure of Feynman integrals. In particular, we describe two new classes of constraints on such integrals, that identify discontinuities that either cannot be repeated, or that always give rise to the same result (no matter which other discontinuities are computed first). These new constraints hold at all orders in dimensional regularization, and provide us with new input for the Landau bootstrap, where information about the singularities and discontinuities of individual Feynman integrals is used to construct their functional form.

We investigate the dynamics of vector excitations localized on cosmic strings in the Abelian-Higgs model. These confined gauge field fluctuations behave as massive vector degrees of freedom propagating along the string. We show that they remain bounded for all values of the scalar self coupling $\lambda$, including parameter regimes in which the previously studied conventional shape mode is no longer present. After determining their spectra and spatial profiles, we analyze their decay through nonlinear coupling to bulk radiation. Their amplitudes exhibit the characteristic power law relaxation associated with non-linear radiation. For sufficiently large $\lambda$ the scalar radiation channel becomes kinematically inaccessible and the decay is instead mediated by quasinormal modes which can be interpreted as Feshbach resonances of the string. We then study the full $3+1$ dimensional dynamics of the vector-excited string. Field theory simulations reveal a parametric instability between the vector mode and the Goldstone sector. In contrast to the shape mode, the vector mode resonantly excites both transverse directions simultaneously. In addition, we build an effective model that captures the instability and identifies the nonlinear couplings responsible for it. Our results show that vector excitations constitute a long-lived massive degree of freedom with a non-trivial role in the dynamics of local strings.

The excursion-set formalism provides a key connection between primordial density fluctuations and the abundance of cosmic structures such as dark matter halos and voids, traditionally assuming Gaussian random walks. In this work, we extend this framework to fluctuations whose distribution presents strongly non-Gaussian tails. Such tails are beyond the reach of perturbative approaches to primordial non-Gaussianity based on moment expansion. We address the problem with rigorous, analytical derivations relying on the large deviation principle, suited for the study of rare fluctuations. We derive new first-passage time distributions for random walks with non-Gaussian statistics and obtain updated predictions for the halo mass function. We also study the two-barrier problem relevant to cosmic void formation, leading to a new analytical prediction for the void size function, with improved accuracy on large scales. Our results demonstrate the potential of large deviation techniques as a bridge between inflationary scenarios, often leading to strongly non-Gaussian tails, and late-Universe observables.

Interactions between dark matter and dark energy can lead to an apparent phantom-crossing behavior that mimics the expansion history preferred by the latest cosmological observations from DESI baryon acoustic oscillations (BAO), Cosmic Microwave Background (CMB), and Type Ia supernovae (SNe Ia) data. In a previous paper [Khoury, Lin, and Trodden 2025 arXiv:2503.16415], we proposed a concrete particle physics realization of this idea, consisting of a strongly coupled dark sector in which a dark axion is coupled to dark baryons. In this paper, we investigate this idea further by comparing its predictions to the latest cosmological data. We implement the dark axion-dark baryon interaction model in a Boltzmann code and confront it with CMB, DESI DR2 BAO, and SNe Ia data. For the CMB+DESI DR2+DES-Dovekie combination, the best-fit model improves the fit relative to $\Lambda$CDM by $\Delta\chi^2=-14.48$. The preferred solution exhibits a non-monotonic dark-matter mass evolution: the mass decreases between matter-radiation equality and recombination, while increasing over the BAO/SNe-sensitive epoch, leading to an apparent phantom crossing in an effective dark-energy description. Interestingly, the same dynamics produces an Early Dark Energy-like energy injection near matter-radiation equality, but in the data-preferred region this component is too small to raise $H_0$ enough to substantially reduce the current tension.

We introduce a foundation model for event classification in high-energy physics, built on a Graph Neural Network architecture and trained on 120 million simulated proton-proton collision events spanning 12 distinct physics processes. The model is pretrained to learn a general and robust representation of collision data using challenging multiclass and multilabel classification tasks. Its performance is evaluated across seven event classification tasks, which include new physics processes not encountered during pretraining as well as ATLAS Open Data to demonstrate generalizability across different simulation frameworks, from Delphes fast simulation to full ATLAS detector simulation. Fine-tuning the pretrained model significantly improves classification performance, particularly in scenarios with limited training data, demonstrating gains in both accuracy and computational efficiency. To investigate the underlying mechanisms behind these performance improvements, we employ a representational similarity evaluation framework based on Centered Kernel Alignment. This analysis reveals that encoder-stage representations of the fine-tuned model remain similar to those of the baseline, while intermediate graph processing layers diverge substantially, indicating that fine-tuning preserves general-purpose encoders while developing fundamentally different message-passing pathways to arrive at superior task performance.

The violation of the charge-parity (CP) transformation symmetry, which although has been observed in plenty of pure meson decay processes, was only confirmed just very recently by the LHCb collaboration in the four-body decay of the heavy baryon $\Lambda_b^0$, $\Lambda_b^0\to p K^- \pi^+ \pi ^-$, through a comparison of the decay branching ratio with that of the CP-conjugate process. However, the detailed dynamics behind this CP asymmetry is obviously far from clear. In this paper, we propose a formalism for the full analysis of the decay angular correlations in four-body cascade decays of heavy hadrons which can provide more information about the CP violation in these decays. To illustrate this, we apply the decay angular correlation analysis of CP violation to another four-body decay channel that involve baryons, $B^0\to p\bar{p}K^+\pi^-$, which has also been investigated by the LHCb collaboration with no evidence of CP violation being found. Surprisingly, based on a simple assumption on the statistical errors, and with the event yield extracted inversely from the published data of LHCb, we obtain non-zero CP asymmetries of about $10\%$ corresponding to the decay angular correlations, which are considerably larger than the CPA asymmetries observed in the $\Lambda_b^0\to p K^- \pi^+ \pi ^-$ channel. We suggest our experimental colleagues to perform full decay angular correlation analyses of CP violation in four-body decays of heavy hadrons, including the above two decay channels.

We propose a minimal, fully thermal mechanism that resolves the long-standing tension between achieving the observed dark-matter relic abundance and explaining the astrophysical signatures of self-interactions. The framework introduces two mediators: a light scalar $\phi$ (MeV scale) that yields the required, velocity-dependent self-interactions, and a heavy scalar resonance $\Phi_h$ (TeV scale) with mass $m_{\Phi_h}\!\approx\!2m_\chi$ that opens an $s$-channel resonant annihilation during freeze-out. This clearly decouples early-universe annihilation from late-time halo dynamics. A detailed numerical analysis identified a narrow predictive island of viability. A representative benchmark with $m_\chi\!=\!600$~GeV, $m_\phi\!=\!15$~MeV, and $m_{\Phi_h}\!\simeq\!1.2$~TeV reproduces the relic density and yields $\sigma_T/m_\chi\sim 0.1$--$1~\mathrm{cm}^2\!/\mathrm{g}$ at dwarf-galaxy velocities while satisfying cluster bounds. The model makes sharp, testable predictions: a narrow $t\bar t$ resonance near $1.2$~TeV within HL-LHC reach, and a spin-independent direct-detection signal $\sigma_{\rm SI}\!\sim\!7\times10^{-48}\,\mathrm{cm}^2$ within next-generation sensitivity. As an optional UV completion, we show that walking $\mathrm{SU}(3)_H$ gauge theory with $N_f=10$ naturally realizes the near-threshold relation $m_{\Phi_h}\!\approx\!2m_\chi$ and can furnish an effective anomalous dimension $\gamma\!\approx\!0.5$ which underlies a density-responsive dark-energy sector, suggesting a unified origin for the dark sector.

Axions that couple to electromagnetism are produced in the early Universe by, among other channels, freeze-in via the Primakoff process. For sufficiently large axion masses, the same coupling causes the axions to decay into two photons, which subsequently ionize the intergalactic medium. If this decay occurs in the redshift range $20 \lesssim z \lesssim 1100$, then the contribution to the cosmic microwave background optical depth $\tau_{\rm reio}$ can lead to a conflict with observations, excluding models with sufficiently strongly coupled, heavy axions and high reheating temperatures, $T_{\rm reh}$. Using large ensembles of explicit type IIB string theory models with up to $h^{1,1} = 100$ axions, we compute the full cosmic reionization history caused by the decays of multiple axions. We compare this to the posterior on the high-$z$ component of $\tau_{\rm reio}$ derived from parametric-independent constraints on the ionization state of the Universe, obtained in a full \textit{Planck} analysis presented in a companion paper. For $h^{1,1} = 20, 50, 100$, we find that approximately 15\%, 15\%, and 10\% of the models in the ensemble prefer $T_{\rm reh} \lesssim 10^{10}\,\text{GeV}$ at 95\% CL. We provide a publicly available code at:~\href{this https URL}{this http URL}, which computes the reionization history for arbitrary ensembles of decaying axions. Our analysis opens the door for future large-scale work studying the preference for low-temperature reheating in models with multiple axions.

In this work, we first present a systematic investigation of the $T_{\bar{c}\bar{s}}$-type charmed-strange molecular tetraquark candidates composed of a $K^{(*)}$ meson and a $T$-doublet anticharmed meson using the one-boson-exchange model, which exhibit exotic flavor content $\bar{c}\bar{s} q q$. Our results suggest that the $K^* \bar D_1$ states with $I(J^P)=0(0^-,\,1^-)$ and the $K^* \bar D_2^*$ states with $I(J^P)=0(1^-,\,2^-)$ represent the most promising candidates of the $T_{\bar{c}\bar{s}}$-type charmed-strange molecular tetraquarks, while the coupled $K \bar D_1 / K^* \bar D_1 / K^* \bar D_2^*$ system with $I(J^P)=0(1^-)$ and the coupled $K \bar D_2^* / K^* \bar D_1 / K^* \bar D_2^*$ system with $I(J^P)=0(2^-)$ can only be regarded as the possible candidates of the $T_{\bar{c}\bar{s}}$-type charmed-strange molecular tetraquarks. We further extend our analysis to the $K^{(*)} {D}_1/K^{(*)} {D}_2^*$ systems, where our results suggest a series of $T_{c \bar s}$-type charmed-strange molecular tetraquark candidates. These findings provide a comprehensive picture of the molecular spectrum in the charmed-strange tetraquark sector composed of $S$-wave kaons and (anti-)charmed mesons in the $T$-doublet and can be tested in future experimental studies.

We extend the range of application of the relativistic Dyson-Schwinger/Bethe-Salpeter approach from previously discussed mesons with total angular momentum $J \le 3$ to the ones with $J=4,5$. On a technical level, the new element is the general Dirac tensor representations for the latter which, to our knowledge, are presented here for the first time. As a first application, we provide an exploratory spectrum for these mesons in a rainbow-ladder truncation of Dyson-Schwinger and Bethe-Salpeter equations. We discuss the merits and limitations of this truncation and explore the shape of the heavy-quark potential corresponding to the underlying effective running coupling. With our predictions for the masses of ground state mesons with quantum numbers $J^{PC}=3^{--}, 4^{++}, 5^{--}$ we identify Regge trajectories in channels where the interaction model can be trusted on a semi-quantitative level. In other channels, discrepancies with experiments confirm the well-known need to go beyond rainbow-ladder in the Dyson-Schwinger/Bethe-Salpeter approach by using more sophisticated interactions.

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 regions of parameter space previously excluded by supernova cooling. The results presented are intended as a proof-of-principle demonstration of how astrophysical dark matter populations can alter supernova cooling constraints and do not provide precision exclusion limits on any given model.

Any viable inflationary model must account for reheating of the universe prior to the onset of primordial nucleosynthesis. In this work, we study the (p)reheating mechanism for an inflaton field with a quartic minimum of the T-model kind with coupling $\lambda$, prior to and post fragmentation, making a clear distinction between the two regimes. We assume that the main particle production channel corresponds to the decay into a pair of spin 1/2 fermions via Yukawa-like interactions. On top of its decays, we also consider the self-interaction of the inflaton, which sources the resonant growth of inflaton inhomogeneities, possibly leading to its eventual fragmentation. By means of a combination of non-perturbative (Heisenberg/Bogoliubov) and perturbative (Boltzmann) methods, we find that for Yukawa couplings that seemed to be intuitively perturbative, such as $y\gtrsim 10^{-8}$ ($y^2/\lambda\gtrsim 3\times10^{-5}$), parametric resonance, kinematic blocking, and Pauli suppression effects cannot be ignored. Additionally, we show that achieving $\rho_\phi \sim \rho_\psi$ prior to fragmentation requires large couplings, $y\gtrsim 0.2$ ($y^2/\lambda\gtrsim 10^{10}$), which needs a detailed study of backreaction and radiative corrections. Thus the rest of our work constitutes studying post-fragmentation fermion production where we conclude that, in general, reheating in this setup is not possible and thus we conclude that in order to successfully reheat, one must invoke a coupling to a integer- and/or 0-spin particle like a scalar boson.

Electromagnetic form factors constitute a natural portal for accessing states beyond the Standard Model. In particular, dimension-5 magnetic and electric dipole moment operators offer a minimal and predictive framework for Feebly Interacting Particles (FIPs). In this work, we perform a study of the sensitivity reach of the Scattering and Neutrino Detector (SND@LHC) in the detection of dipolar dark states through photon-mediated interactions with the Standard Model particles. The far-forward region of the LHC provides FIPs with large momenta that scatter off electrons and nuclei inside the target. Production of dark states from meson decays is constrained by invisible decay widths, while the Drell-Yan process offers a production channel in the GeV range. We present sensitivity plots for magnetic and electric dipole moment interactions at SND@LHC and compare them with constraints from direct detection, beam dump, fixed-target, and collider experiments. The validity of the effective theory that describes the dipole model is also studied by considering conservative bounds on the couplings.

We discuss key aspects of the nature of radiation from global strings and its impact on the relic axion density. Using a simple model we demonstrate the dependence on the spectrum of radiation emitted by strings. We then study the radiation emitted by perturbed straight strings paying particular attention to the difference between the overall phase of the field and the small perturbations about the string solution which are the axions. We find that a significant correction is required to be sure that one is analyzing the axions and not the self-field of the string. Typically this requires one to excise a sizeable region around the string - something which is not usually done in the case of numerical field theory simulations of string networks. We have measured the spectrum of radiation from these strings and find that it is compatible with an exponential, as predicted by the Nambu-like Kalb-Ramond action, and in particular is not a ``hard'' spectrum often found in string network simulations. We conclude by attempting to assess the uncertainties on relic density and find that this leads to a range of possible axion masses when compared to the measured density from the Cosmic Microwave Background, albeit that they are typically higher than what is predicted by the Initial Misalignment Mechanism. If the decay is via a ``soft spectrum'' from loops produced close to the backreaction scale we find that $m_{\rm a}\approx 160\,\mu{\rm eV}$ and a detection frequency $f\approx 38\,{\rm GHz}$. If axions are emitted directly by the string network, and we use emission spectra reported in field theory simulations, then $m_{\rm a}\approx 4\,\mu{\rm eV}$ and $f\approx 1\,{\rm GHz}$, however this increases to $m_a \approx 125\,\mu{\rm eV}$ and $f\approx 30\,{\rm GHz}$ using our spectra for the case of an oscillating string. In all scenarios there are significant remaining uncertainties that we delineate.

We introduce an anomaly-based framework to probe quark electric dipole moments in exclusive hadronic final states produced in $e^+e^-$ annihilation. Chern-Simons-induced anomalous couplings yield a clean T-odd asymmetry $A_T$ from interference between the Standard-Model amplitude and dipole-moment contributions. As an application, $\gamma^\ast\to K^+K^-\pi^0$ provides direct sensitivity to the strange-quark EDM $d_s$ in the chiral limit. The precision on $d_s$ can reach $\mathcal{O}(10^{-16})\,e\cdot\mathrm{cm}$ with existing CMD--3 data and $\mathcal{O}(10^{-18})\,e\cdot\mathrm{cm}$ using current $J/\psi$ samples at BESIII, improving the current direct constraint from hyperon EDM by two to three orders.

Given the non-negligible interplay between parton distribution functions (PDFs) at large x and potential New Physics (NP) effects in the high-energy tails of hadron collider observables, a central question is which PDFs can be reliably employed in beyond-the-Standard-Model (BSM) analyses. In this work, we examine the fine balance between using PDF sets with small uncertainties in the large-x region -- crucial for maximising BSM sensitivity -- and adopting conservative PDF fits that exclude high-energy data potentially contaminated by unaccounted NP contributions. We systematically assess a range of conservative PDF fitting strategies designed to mitigate such biases and provide a recommendation for the class of PDFs best suited for robust BSM searches. In addition, we investigate the alternative approach of performing simultaneous fits of Standard Model Effective Field Theory (SMEFT) Wilson coefficients and PDFs, thereby consistently accounting for their mutual correlations. Starting from a toy model to illustrate the underlying mechanisms, we then analyse two realistic NP scenarios: one modifying high-mass Drell-Yan production and another affecting the high-invariant-mass tail of top-quark pair production. Both cases are representative of measurements that will be probed with high precision during the High-Luminosity phase of the LHC.

In recent years, long-lived particles (LLPs) have attracted increasing attention in searches for physics beyond the Standard Model (SM). In this paper, we investigate the discovery prospects for light long-lived ALPs predicted by the photophobic ALP scenario via displaced vertex signals at the CEPC with the center-of-mass energy $\sqrt{s}=91.2 $ GeV and integrated luminosity $\mathcal{L}=$ $100$ ab$^{-1}$. After comparing several possible single-production processes of the photophobic ALP, we focus on the dominant process $e^+ e^- \to Z \to a \gamma $, with the ALP $a$ subsequently decaying into a pair of displaced charged leptons. Dedicated Monte Carlo simulations are performed for the $\mu^+ \mu^- \gamma$ and $\tau_h^+ \tau_h^- E\mkern-10.5 mu/_T \gamma$ signals. For the $\mu^+\mu^-\gamma$ signal, the CEPC is sensitive to the parameter region $g_{aWW} \in [1.27\times10^{-3},6.80\times10^{-1}]~\mathrm{TeV}^{-1}$ for $m_a \in [1,4]~\mathrm{GeV}$. For the $\tau_h^+\tau_h^-E\mkern-10.5 mu/_T\gamma$ signal, the accessible region is $g_{aWW} \in [7.00\times10^{-4},9.40\times10^{-3}]~\mathrm{TeV}^{-1}$ with $m_a \in [4,9]~\mathrm{GeV}$. These results demonstrate the strong potential of the CEPC to explore light long-lived ALPs via displaced vertex signals, providing complementary coverage to existing searches at the LEP and LHC, as well as to the projected reach of the HL-LHC.

The Higgs boson decay to massive bottom quarks has the largest branching ratio. The decay is mainly induced by the bottom-quark Yukawa coupling with the decay rate calculated up to $O(\alpha_s^4)$ assuming the massless final-state bottom quark. The top-quark Yukawa coupling induced contribution starts at $O(\alpha_s^2)$, and exhibits logarithmic and power enhancements, making the perturbative expansion converge slowly, which is a feature not present in the hadronic Higgs boson decay. We present a calculation of such contributions at $O(\alpha_s^4)$ to the decay into massive bottom quarks in which the squared amplitudes contain two top-quark Yukawa couplings and the final state must include at least a bottom quark pair. We find that they increase the decay width, relative to the result up to $O(\alpha_s^3)$, by $0.4\%$, larger than the experimental precision at future lepton colliders, and reduce the scale dependence significantly down to $0.4\%$.

By exploiting small-scale structure formation probed by Lyman-$\alpha$ forest observations, we study constraints on a model of dark matter from dark sector decay. We compute the phase space distribution of the dark matter and the linear matter power spectrum. We map the non-thermal dark matter distribution in this dark matter model to an approximate thermal warm dark matter distribution, and use this approximation to obtain a constraint from the Lyman-$\alpha$ forest observation. We combine the latest Lyman-$\alpha$ forest bounds with the constraint from the Big Bang Nucleosynthesis. As these two probes offer highly complementary constraints, we impose strong limits on sub-GeV dark matter. Consequently, masses lighter than $\sim 10^{-1}$ GeV are excluded, thereby significantly limiting the allowed parameter space. More broadly, our findings demonstrate the utility of small-scale structure observations in testing non-thermal dark matter paradigms, offering valuable insights for exploring a wider class of late-time decay models.

Understanding the origin of flavour hierarchies in the Standard Model remains an open problem, motivating extensions with non-trivial flavour symmetries. We unify deconstructed weak isospin $\mathrm{SU}(2)_\mathrm{L}^3$ into an $\mathrm{Sp}(6)_\mathrm{L}$ symmetry at a high scale $v_S$. The three generations of Standard Model (SM) left-handed doublets are unified into a single fundamental representation of $\mathrm{Sp}(6)_\mathrm{L}$. In addition to two BSM triplets from the breaking of $\mathrm{SU}(2)_\mathrm{L}^3$, the enlarged symmetry predicts six additional gauge bosons below the unification scale: three $\mathrm{SU}(2)_\mathrm{L}$ triplets and three singlets, which induce flavour transitions in both the quark and lepton sectors, even in the presence of mass-gauge alignment. We derive updated bounds on the intermediate breaking scale $v_{12}$ of $\mathrm{SU}(2)_\mathrm{L}^3$ in the presence of the unification scale $v_S$, mapping exclusions in the $(v_{12}, r)$ parameter space with $r = v_S^2 / v_{12}^2$. The most stringent constraints arise from precision flavour observables involving first- and second-generation transitions, including neutral meson mixing ($K^0 - \bar{K}^0$, $D^0 - \bar{D}^0$), $\mu \to 3e$ and $\mu \to e$ conversion in nuclei. These measurements probe scales well beyond direct collider reach and imply $v_{12} \gtrsim 550 ~\mathrm{TeV}$ for small $r \approx 1$, while for $r\gtrsim100$ the bound relaxes to $v_{12} \gtrsim 150~\mathrm{TeV}$, recovering the limits of the $\mathrm{SU}(2)_\mathrm{L}^3$ model. Additionally we include projections from Mu3e and COMET-I and -II experiments which show promising further reach into the parameter space.

In our earlier work [Phys. Rev. C \textbf{98}, 045209 (2018)], we analyzed the differential cross-section data from the CLAS Collaboration for the reactions $\gamma p \to K^{*+}\Sigma^0$ and $\gamma p \to K^{*0} \Sigma^+$ using an effective Lagrangian approach. We found that a satisfactory description of the data required the inclusion of the $s$-channel $\Delta(1905)5/2^+$ resonance, in addition to $t$-channel exchanges of $K$, $\kappa$, and $K^*$, $s$-channel contributions from nucleons ($N$) and $\Delta$, $u$-channel exchanges of $\Lambda$, $\Sigma$, and $\Sigma^*$, and a generalized contact term. In the present work, we extend our analysis to incorporate the data on spin density matrix elements from the LEPS Collaboration for the $\gamma p \to K^{*0}\Sigma^+$ reaction at photon energies $E_{\gamma} = 1.85$--$2.96$ GeV. Our goal is to impose more stringent constraints on the theoretical model and obtain a more reliable understanding of the reaction mechanisms. We obtain two fits that describe the experimental data equally well. In both fits, the $\Delta(1905)5/2^+$ resonance plays an important role. However, the contribution from $t$-channel $\kappa$ exchange is significant in one fit but negligible in the other. This finding contradicts earlier claims in the literature that the LEPS parity spin asymmetry $P_\sigma$ data support a dominant role of $\kappa$ exchange in $\gamma p \to K^{*0}\Sigma^+$. We also present predictions for $P_\sigma$ at $E_\gamma = 8.5$ GeV, which may help clarify whether $\kappa$ exchange is indeed dominant in this reaction.

We study the impact of radiation on quantum systems defined by the spins of elementary fermion-antifermion pairs produced at colliders. We present predictions for several processes, showing that energetic final-state radiation can induce decoherence and significantly reduce the entanglement of quantum systems formed by elementary fermion pairs. We investigate the feasibility of observing this effect experimentally in exclusive samples with energetic radiation. A statistically significant signal can be obtained with current data in associated $pp \rightarrow t\bar{t}(g)$ production at the LHC and in $e^+e^- \rightarrow \tau^{+}\tau^{-}(\gamma)$ production at Belle 2. Future electron-positron colliders operated at the $Z$ pole or well above the $t\bar{t}$ production threshold will extend these prospects further.

We develop a novel model utilizing the forward $K^*$ production reaction off the nucleon, $\pi N \to K^* MB$, induced by a high-momentum $\pi$ beam, as a tool to study low-lying $Y^*$ resonances below and just above the $\bar{K}N$ threshold. Because conventional $K^- p$ scattering experiments face difficulties in directly accessing this kinematic region, the proposed reaction offers a valuable complementary approach for $Y^*$ spectroscopy. The constructed model is based on the one-meson exchange mechanism, which is known to dominate forward-angle production at high energies, and the half-off-shell scattering amplitudes from the ANL-Osaka dynamical coupled-channels models (Model A and Model B). We predict various observables, including differential cross sections and angular distributions. Our results demonstrate significant enhancements in the subthreshold region of the invariant mass spectra. Notably, we show that overlapping resonances, such as a potential new $3/2^+$ $\Sigma$ state and the well-established $\Sigma(1385)3/2^+$, can constitute a single peak in the $\pi\Lambda$ mass spectrum, indicating that the existence of previously unconfirmed subthreshold states cannot be ruled out by analyzing only the existing mass spectrum data. Furthermore, we find that angular distributions provide strong discriminatory power to disentangle such overlapping states through partial-wave interference effects, while the $t'$ and $\phi_M^*$ dependencies provide crucial constraints on the high-energy production mechanisms. Our predictions for these highly sensitive observables can facilitate high-statistics measurements, which are accessible at modern hadron facilities such as J-PARC, to unravel the $S=-1$ $Y^*$ mass spectrum.

The hadronic tensor molecule $\mathcal{M}=J/\psi J/\psi$ is investigated in the framework of QCD sum rule method. We evaluate its mass and current coupling using the two-point SR approach. Our result $m=(6290 \pm 50)~ \mathrm{MeV}$ for the mass of $\mathcal{M}$ indicates that it can decay to a pair of mesons $J/\psi J/\psi$. Apart from this dominant channel there are subdominant modes of the molecule $\mathcal{M}$ generated due to annihilation of constituent $\overline{c}c$ quarks to pairs of light quarks $ \overline{q}q$ and $\overline{s}s$. This mechanism launches processes $ \mathcal{M} \to D_{(s)}^{(\ast )+}D_{(s)}^{(\ast )-}$, $DD_{1}(2420)$, $ D_sD_{s1}(2460)$ and $D_{(s)}^{(\ast )0}\overline{D}_{(s)}^{(\ast )0}$. The decays of $\mathcal{M}$ are explored by applying technical tools of the three-point sum rule approach which is necessary to estimate strong couplings at $\mathcal{M}$-meson-meson vertices. Comparing the mass $m$ of the molecule $\mathcal{M}$ and its decay width $\Gamma[\mathcal{M}]=(149 \pm 21)~ \mathrm{MeV}$ with available experimental data, we discuss the molecule $\mathcal{M}$ as a possible candidate to the tensor resonance $X(6200)$.

We propose a novel search strategy for heavy Majorana neutrinos based on the lepton-number-violating process $\mu^{-}p \to jN \to j(\ell^{+}W^{-})$ at future muon-proton ($\mu p$) colliders equipped with 1 TeV muon beams and 7 TeV proton beams, yielding a center-of-mass energy of approximately 5.3 TeV. For heavy neutrinos with masses in the range $200~\text{GeV} \lesssim m_N \lesssim 1000~\text{GeV}$, this analysis targets the decay chain $N \to \ell^{+}W^{-} \to \ell^{+}jj$, producing a characteristic final state consisting of one charged lepton and three well-resolved jets. For TeV-scale Majorana neutrinos, the $W$ boson is highly boosted, such that its hadronic decay products coalesce into a prominent fat-jet ($J$) signature. We conduct comprehensive signal and background analyses that account for realistic detector effects to assess the search sensitivity. We derive the projected $2\sigma$ exclusion limits on the neutrino mixing parameter $|V_{\ell N}|^2$ based on two typical integrated luminosity scenarios of $100~\text{fb}^{-1}$ and $1~\text{ab}^{-1}$. The results demonstrate that the proposed search strategy can achieve constraints substantially superior to the existing bounds from the LHC and other high-energy colliders. This study demonstrates that future $\mu p$ colliders can provide competitive sensitivity for probing heavy Majorana neutrinos over the mass range $200~\text{GeV} \leq m_N \leq 3000~\text{GeV}$.

We propose a novel model for pseudo-scalar dark matter (PSDM) by extending the Standard Model (SM) with a dark gauged $U(1)_X$ symmetry, but without dark charged fermions. We impose a $Z_2$ symmetry to ensure the stability of pseudo-scalar dark matter and regard the $U(1)_X$ symmetry as being broken dominantly by a large VEV of the singlet scalar field. The would-be Goldstone associated with the $U(1)_X$ gauge boson is almost orthogonal to the direction of PSDM. As a result, we show that PSDM appears as a stable pseudo-Nambu-Goldstone boson receiving the mass from the $U(1)_X$ invariant mixing potential and the corresponding cross section for direct detection gets suppressed even for the weak-scale mass of PSDM. We also show that the correct relic density can be explained by the PSDM annihilations into the SM particles or into a pair of light Higgs-like scalars, being compatible with the bounds from Higgs invisible decay, Higgs data and indirect detection.

Using the quantum field theory, we derive a Breit-Wigner-type formula for the $e^+ e^-$ annihilation into a vector meson and its antiparticle, and relate the formula parameters to observable quantities. The formula's soundness is checked by fitting the $e^+ e^- \to D^{\ast+}D^{\ast-}$ data published by the BESIII Collaboration in 2022.

The Drell-Yan process is a key precision benchmark at the Large Hadron Collider and a sensitive probe of SM and SMEFT effects. Fully exploiting future LHC data requires percent-level SM predictions, motivating precise EW and mixed QCDxEW corrections. In this proceeding we report of the progress towards the calculation of mixed QCDxEW corrections to charged-current Drell-Yan with leptonic decay at high transverse masses, performed within the Nested Soft-Collinear Subtraction framework. After presenting a validation at NLO, we show results for the NNLO real corrections and compare their impact in the neutral-current and newly developed charged-current channels. These contributions are essential to match the current and future precision of LHC measurements, especially in regions where electroweak effects are enhanced by Sudakov logarithms.

The memory effect is known to introduce a permanent displacement in the gravitational wave (GW) detectors after the passage of a GW signal. While the $\textit{linear memory}$ adheres to the source properties, the $\textit{non-linear memory}$ is a secondary effect sourced by the GW itself. In the present work, we discuss GW signals with both these kinds of memory effects, while focusing on the parabolic limit of an encounter. This special case is theoretically intriguing and emerges as a limiting situation for both eccentric and hyperbolic events. However, in this paper, we argue that a simple extrapolation of memory calculations for eccentric or hyperbolic cases to the parabolic case may lead to incorrect estimations. Therefore, we treat the parabola as a special case and use an intrinsic parameterization, with which we calculate gravitational wave signals and their energy spectrum via an effective field theory formalism. Unlike the hyperbolic case, which is known to have linear memory, we notice that parabolic encounters bring out new features in the zero frequency limit (ZFL). The exactly parabolic case is studied here primarily as an idealized separatrix between bound and unbound motion, and our analysis highlights some of the key challenges and salient aspects of GW memory in this regime.

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.