New articles on High Energy Physics - Phenomenology


[1] 2606.06541

Soft UV Completion of a Preon Model

We build a framework for Regge trajectories from the Nambu-Goto action. We compute the 6-preon Regge trajectory in a preon model, include the worldsheet conformal anomaly, and build the parameter-free Veneziano amplitude. The amplitude has s-channel poles matching the spectrum to 0.5%, and at fixed-angle scattering decays exponentially with a negative Gross-Mende coefficient, realized numerically to 0.03%. This is a soft, genuinely non-perturbative ultraviolet completion of the preon model - and thereby of the Standard Model, which emerges as its low-energy limit.


[2] 2606.06580

Neutrino mass ordering from the next Galactic supernova at DUNE, HK, and JUNO

The next Galactic core-collapse supernova (CCSN) will offer a unique opportunity to determine the neutrino mass ordering. We focus on two observables: the electron neutrino ($\nu_e$) neutronization burst and the rise-time of the electron antineutrino ($\bar{\nu}_e$) flux during the accretion phase. The neutronization burst, a sharp $\nu_e$ peak within $\sim 20$-$30$ ms, provides a clean and robust signature of mass ordering through its appearance or disappearance. During the accretion phase, the faster rise of heavy lepton flavor neutrinos ($\nu_x$) leads to a distinct faster rise-time behavior of the oscillated $\bar{\nu}_e$ signal, resulting in mass ordering discrimination. Using realistic CCSN simulations for multiple progenitor masses, we compute event rates and perform a statistical analysis for a Galactic ($10$~kpc) CCSN event at DUNE, Hyper-Kamiokande (HK), and JUNO detectors. The neutronization burst remains largely independent of SN hydrodynamic simulation models, with DUNE and HK achieving $\gtrsim 6\sigma$ and $\gtrsim 4\sigma$ sensitivity for normal (NO) to inverted ordering (IO) discrimination, respectively. However, the rise-time observable is prone to progenitor degeneracies. To mitigate this cumulative and ratio-based observables constructed at characteristic timescales ($20$ ms & $100$ ms) are used. The resulting confidence levels from the rise-time analysis to discriminate IO/NO in HK and JUNO are $\sim 5\sigma$ and $\sim 3\sigma$, respectively. Our results highlight the complementarity of detectors and observables, and demonstrate that combining neutronization burst and accretion phase information will be crucial for a definitive determination of the neutrino mass ordering in the next Galactic supernova.


[3] 2606.06587

A New Origin of the Big Bang from Dark-Sector-Induced Vacuum Decay and Its Gravitational-Wave Signal

We propose a novel scenario for the onset of the thermal Big Bang. In this framework, the inflaton transfers its energy exclusively into a dark sector, leaving the Standard Model (SM) sector temporarily trapped in a false vacuum. As the Hubble expansion rate rapidly decreases, the SM phase transition eventually completes, and the standard thermal Big Bang era commences upon the thermalization of the highly energetic bubble walls. We demonstrate that the large Lorentz boost of these bubble walls, combined with their Hubble-scale macroscopic size, generates distinctive gravitational-wave signatures from the SM vacuum decay. This stochastic gravitational-wave background provides a powerful new probe of the early Universe's expansion history, with a present-day energy density fraction that can reach $\Omega_{\text{GW}} \sim 3\times10^{-8}$.


[4] 2606.06603

Reweighting Adversarial Networks for Unbinned Unfolding

Differential cross sections are the currency of scientific exchange in particle and nuclear physics. Recently, machine learning methods have enabled unbinned and high-dimensional cross section measurements through new approaches to unfolding. A key challenge with unfolding is that it is a bi-level optimization problem where constraints are available at the detector level while the target is at the particle level, linked by a stochastic detector response. Further complications arise when the particle-level and detector-level distributions have non-overlapping or only partially overlapping support, which can destabilize training and degrade unfolding performance. In this paper, we introduce a new unbinned unfolding technique called the Reweighting Adversarial Network (RAN), which can be viewed as a generalization of the Moment Unfolding protocol to accommodate full phase-space unfolding. RANs address the bi-level optimization problem through a particle-level reweighting function steered by a Wasserstein critic at the detector level. RANs do not require overlapping support at the detector level, nor multiple iterations of training. We evaluate the performance of RANs with Gaussian data and jet substructure studies, including cases specifically designed to stress test the method under vanishing support overlap. We demonstrate that RANs outperform state-of-the-art methods in accuracy and have a lower computational overhead.


[5] 2606.06606

Discovering the Axiverse via Fifth Forces

If the Universe is described by string theory or other extensions of the Standard Model, several light, axion-like states are predicted to exist. However, most experiments only search for one of these states. We show that searches for fifth forces can't assume a non-relativistic potential induced by a single axion field. We discuss the strength of the non-relativistic spin-dependent and spin-independent potentials in the most general case of $N_a$ different axions and show how the shape of the potentials can be used to distinguish between different axiverse scenarios.


[6] 2606.06607

Photons, jets and missing momentum from a two-vector dark sector

We investigate the LHC phenomenology of a vector dark-sector effective theory containing two neutral massive vector states, both odd under a dark-parity symmetry. The lightest state is stable and provides a dark-matter candidate, while the leading interactions with the Standard Model arise from dimension-six operators involving the hypercharge field strength. In the prompt-decay regime considered in this work, the heavier state can decay radiatively, leading to a $\gamma+\text{jets}+E_T^{\text{miss}}$ signature when the two dark vectors are produced in association with QCD radiation. We study this topology at the LHC through a cut-based analysis, comparing an inclusive missing-transverse-momentum selection with a three-bin strategy that retains coarse shape information. The binned analysis is found to substantially improve the expected reach and probes regions of the parameter space compatible with the observed relic abundance in the standard freeze-out scenario. We also discuss the freeze-in interpretation and the limitations associated with the EFT description at high masses.


[7] 2606.06629

Neutrino Oscillations as an Open Quantum System in Strong Gravitational Fields: Spin-Connection Decoherence and Kerr Frame Dragging

We investigate neutrino flavor evolution in strong gravitational fields within an open-quantum-system framework in curved spacetime. Starting from the Dirac equation in the vierbein formalism, we construct an effective flavor Hamiltonian incorporating gravitational redshift, spin--curvature couplings, and Kerr frame-dragging effects. Treating spin-connection fluctuations as a stochastic gravitational environment, we derive a Lindblad master equation and introduce a curvature-enhanced decoherence rate governed by local spacetime geometry. We compute oscillation probabilities, coherence loss, flavor-ratio distortions, entanglement entropy generation, and event-rate modifications for neutrinos propagating near Schwarzschild and Kerr compact objects. The resulting signatures are compared with projected sensitivities of IceCube-Gen2, KM3NeT, and P-ONE, and are further quantified through detector-level significance estimates. Our results provide a unified effective framework linking neutrino oscillations, gravitationally induced decoherence, quantum-information observables, and high-energy astrophysical neutrino measurements in strong-curvature environments.


[8] 2606.06645

micrOMEGAs 7: Beyond standard cosmology

We present micrOMEGAs7, a major upgrade of the micrOMEGAs package for the computation of dark matter observables in generic models. This release introduces a generalized treatment of the Boltzmann equations, allowing for user-defined modifications of the Hubble expansion rate, entropy evolution, and non-thermal dark matter production from late-decaying cosmological components, thereby extending the framework beyond the standard radiation-dominated cosmology. The relic density can now be computed in scenarios such as low-temperature reheating, early matter domination, and kination. The new version also improves the treatment of sub-GeV dark matter, in particular annihilation into light mesons through scalar mediators, and provides updated spectra for indirect detection. Several experimental and observational constraints have been implemented or revised, including CMB bounds from Planck on energy injection during recombination and Fermi-LAT limits from dwarf spheroidal galaxies. For direct detection, a recast of recent LZ results has been included, and the code now takes into account effective electromagnetic couplings of spin-$1/2$ and spin-1 dark matter. Collider observables have also been extended through the implementation of CMS dilepton resonance constraints on $Z'$ mediators. Additional improvements include a more flexible treatment of effective relativistic degrees of freedom and an updated LHAPDF interface.


[9] 2606.06668

A more effective QCD string at colliders: Decay of excited strings and the worldsheet axion

The confining flux tube of $(3+1)$d QCD is described by an effective string theory with $(1+1)$d worldsheet action that extends the Nambu-Goto form by the addition of a massive pseudoscalar worldsheet ``axion". As argued in companion papers concerning the modified phenomenology of the Lund string model at colliders, QCD flux tubes produced by high-energy collisions are likely to involve excitation of both worldsheet Nambu-Goldstone and axion modes, although the standard Lund model assumes a constant tension ground-state string. Here we detail the path-integral computation of the modified Schwinger-like process of string breaking via nucleation of quark-antiquark pairs in the presence of excitations above the string ground state. We find that the worldsheet axion leads to the dominant change in the string breaking process, the axion excitations producing, among other effects, a varying effective tension of the string, which can exponentially enhance or suppress the string breaking rate depending on the local phase of the excitation. Our computation employs a version of the Schwinger-Keldysh complex time contour method with initial state data specified by a density matrix. In an excited background the Euclidean saddle point is generically complex, but its continuation gives real initial data for post-decay evolution. Our results are of relevance for hadronisation models with excited QCD strings.


[10] 2606.06773

Lepton interactions from GeV to EeV

In this work, we investigate the phenomenological consequences of neutrino and muon interactions with matter. In our studies, we focused in phenomenological predictions for two experiments: FASER and IceCube. FASER is a detector located at the LHC that measures neutrinos produced in proton-proton collisions. A new version of FASER, FASER2, has been proposed to operate in the Forward Physics Facility during the high-luminosity regime of the LHC. The intense flux of tau neutrinos expected at FASER2 motivated us to study the polarization effects of the tau produced in charged current interactions. Our results show that the produced taus will not be completely polarized. Among the Standard Model particles, only neutrinos and muons produced in proton-proton collisions at the LHC can reach FASER. In our study, we show that muon-initiated events can reveal interesting nucleon properties, such as nuclear effects and the existence of an intrinsic charm. The high number of events induced by neutrinos at FASER motivated us to study rare processes in neutrino interaction, such as the neutrino trident. Our results indicate that the neutrino trident process can be observed at FASER2. We have also studied muon trident at the LHC, and we showed that tau pair production can be observed for the first time in this reaction. In contrast to neutrinos detected at the LHC, the neutrinos observed at IceCube come from natural sources, being mainly atmospheric and astrophysical neutrinos. IceCube is capable of observing neutrinos across a wide energy spectrum, ranging from a few GeV to beyond PeV. We show that the study of these events can contribute to our understanding of the structure of target hadrons, as well as the search for physics effects beyond the Standard Model in the propagation of these neutrinos in the universe until they reach the Earth.


[11] 2606.06979

Investigation of fully heavy tetraquark within chiral quark model

In the framework of the Chiral quark model (ChQM), we investigate the fully charmed and fully bottomed tetraquark with $J^{PC}=2^{++}$ including two structures: $Q\bar{Q}-Q\bar{Q}$ and $QQ-\bar{Q}\bar{Q}$. The bound-state calculation shows that there is no bound state in either $cc\bar{c}\bar{c}$ or $bb\bar{b}\bar{b}$ systems. However, by using the real-scaling method, some resonance states are obtained. For the $cc\bar{c}\bar{c}$ system, when the channel-coupling includes only three $S$-wave channels, two resonant states are obtained: one with a mass around $7002$ MeV and decay width near $54$ MeV, and another with a mass around $7227$ MeV and a decay width near $66$ MeV. The former can be regarded as a candidate for the $X(6900)$, and the latter can be considered as a candidate for the $X(7200)$. Upon adding the $\chi_{c0}\chi_{c2}$, $\chi_{c1}\chi_{c1}$, $\chi_{c1}\chi_{c2}$, $\chi_{c2}\chi_{c2}$ channels, both resonant states still remain. For the $bb\bar{b}\bar{b}$ system, only one resonant state is obtained, regardless of whether the four channels composition of the excited mesons are included or excluded. The mass and width of this resonant state are around $19743$ MeV and $67$ MeV, respectively. We suggest that future experiments search for the possible resonance state in the invariant mass spectrum of $\Upsilon \Upsilon$ or $\Upsilon \Upsilon(2S)$.


[12] 2606.07008

Macroscopic Quantum Interference in Dark Matter Wave Scattering with MICROSCOPE

Ultralight dark matter behaves as a coherent wave, yet its quantum interference effects of elastic scattering with multiple targets have remained unexplored. We show that the nested test masses of MICROSCOPE realize such an ``interferometer'' for dark-matter wave scattering. Amplitudes from the two concentric cylinders interfere and redistribute the induced force between them. This effect produces unique and rotation-modulated signals set by the target geometry. Developing the theoretical framework and applying it to MICROSCOPE data, we obtain leading constraints on quadratic dark-matter--nucleon coupling for masses $10^{-3}$--$10^{-2}\,$eV, reaching cross sections of order $10^{-52}$ cm$^2$.


[13] 2606.07073

Mechanical distribution of the pseudoscalar charmonium and bottomonium on the light-front

We investigate the energy-momentum tensor of pseudoscalar charmonium and bottomonium within the framework of the light-front quark model. The gravitational form factors (GFFs), namely the $A$ and $D$-terms, are evaluated in terms of the light-front wave functions. The corresponding spatial mechanical distributions in the transverse plane are obtained through the Fourier transform of these GFFs. To examine the sensitivity of the results to the internal quark-antiquark distribution inside the meson, two distinct Gaussian forms are employed for the spatial part of the wave function. We analyze several mechanical properties in the transverse plane, including the momentum density, pressure distribution, shear stress, force density, and internal energy density. The pressure distribution exhibits a node where it changes sign from positive (repulsive) to negative (attractive) with increasing transverse distance. The force distribution remains positive throughout the transverse plane, supporting the stability condition proposed in earlier studies. Most of the spatial distributions, except for the shear stress, are found to be sensitive to the choice of the spatial wave function near the center of the meson, while they become nearly insensitive toward the periphery. In contrast, the shear stress distribution exhibits noticeable sensitivity to the choice of wave function in the intermediate transverse region.


[14] 2606.07106

Joint probes of dark matter annihilation from neutrino detectors and CMB targets

Dark matter (DM) annihilation into neutrinos provides a promising observational channel targeted by current and forthcoming neutrino detectors. However, the detection of such neutrino fluxes alone cannot uniquely determine their astrophysical or cosmological origin, such as the recent observations from Super-Kamiokande that hint at a small excess of electron antineutrino events. We propose that the effective number of neutrino species and the spectral distortion of the cosmic microwave background (CMB) can serve as complementary observables to probe neutrino signatures from DM annihilation. Using a simple model-independent analysis, we determine the detection windows of these cosmic observables that overlap with the experimental sensitivities from the Super-Kamiokande, Jiangmen Underground Neutrino Observatory, Hyper-Kamiokande, and the Deep Underground Neutrino Experiment, showing that joint probes of large DM annihilation to neutrinos with MeV-GeV masses can be achieved by neutrino detectors and CMB experiments.


[15] 2606.07189

VALO1.0: New real-photon parton distributions with Monte Carlo uncertainties

Performing a global QCD analysis of data on the photon structure function $F_2^{\gamma}$ in $e^{+} e^{-}$ scattering, we determine new leading order (LO) and next-to-leading (NLO) parton distributions functions (PDFs) of the real photon. The resulting photon PDFs, referred to as VALO1.0, are obtained in the form of Monte Carlo (MC) replicas which assess the propagation of experimental uncertainties to the PDFs. To achieve well-converging fits, we employ a five-parameter hadron-like ansatz for the boundary conditions with simplifying assumptions on the flavor structure of the quark distributions and the large-$x$ behavior of the gluon distribution. This results in robust quark distributions at both LO and NLO and the gluon distribution at NLO with modest uncertainties, while leaving LO gluons still largely unconstrained. The resulting photon PDFs broadly agree with the parameterizations available in the literature and set the stage for future analyses including additional photoproduction data, which could help to increase the flexibility of our input PDFs. The LO and NLO VALO1.0 photon-PDF replicas, both in the DIS$_{\gamma}$ and $\overline{\rm MS}$ factorization schemes as well as the open-source $\gamma\texttt{EKO}$ code for solving the scale dependence of photon PDFs and the analysis framework $\texttt{VALOfitter}$ are made publicly available.


[16] 2606.07225

Simultaneous Dalitz-plot decomposition of the $e^+ e^- \to J/ψ\, π\, π\, (K \bar{K})$ processes in the 4.13-4.36 GeV region using dispersive final-state interactions

We present a joint analysis of the processes $e^+e^- \to J/\psi\pi^+\pi^-$ and $e^+e^- \to J/\psi K^+K^-$ at center-of-mass energies from 4.13 to 4.36 GeV. The amplitudes are constructed using the Dalitz-plot decomposition formalism, with the $e^+e^-$ energy dependence encoded through the $Y(4220)$ and $Y(4320)$ resonant structures together with a non-resonant production mechanism. The scalar $\pi\pi/K\bar K$ final-state interaction is treated dispersively using a coupled-channel Omnès representation. This allows us to describe the measured total cross sections and one-dimensional invariant-mass distributions with a single set of energy-independent parameters. We find that a purely resonant description of the BESIII data is insufficient, requiring a non-resonant term at the amplitude level which undergoes $\pi\pi/K\bar{K}$ rescattering. Within the present isobar model, we extract Breit-Wigner parameters for the $Z_c(3900)$, $Y(4220)$, and $Y(4320)$ states, and determine the corresponding subprocess cross sections.


[17] 2606.07232

Current and future constraints on heavy New Physics from $τ$ weak dipole moments

We study the weak magnetic and electric dipole moments of the $\tau$ lepton as precision tests of the Standard Model (SM) and probes of heavy New Physics (NP). We present an updated SM prediction for the $\tau$ weak magnetic dipole moment at one loop, including a careful assessment of theoretical uncertainties from electroweak scheme dependence. Working within the SM Effective Field Theory, we derive comprehensive current constraints on the $\tau$ dipole operators from a combination of observables: the $\tau$ weak and electromagnetic dipole moments, high-mass Drell-Yan tails at the LHC, $Z$ partial decay widths, and the electron electric dipole moment. Finally, we assess the prospects of measuring the SM value of the $\tau$ weak magnetic moment at the FCC-$ee$ Tera-$Z$ run, and project the sensitivities of the leading observables to heavy NP at FCC-$ee$ and HL-LHC, paying particular attention to systematic uncertainties. We find that the $\tau$ weak dipole moments are already among the leading probes of the $\tau$ dipole operators, and will become increasingly dominant at future colliders.


[18] 2606.07398

Correlating lepton flavor violating $b \to s$ and leptonic decay modes in a minimal abelian extension of the Standard Model

We examine possible correlations between $b \to s \ell_1^- \ell_2^+$ transitions -- both in the lepton flavor conserving ($\ell_1=\ell_2$) and violating case ($\ell_1 \neq \ell_2$) -- and purely leptonic flavor violating decays within the ABCD model [1], a minimal abelian extension of the Standard Model (SM) introducing a new $\text{U}(1)'$ symmetry. The associated neutral $Z'$ boson has generation-dependent, flavor non-universal couplings to SM fermions, governed by three rational parameters $\epsilon_{1,2,3}$, which sum to zero to ensure gauge anomaly cancellation. Each $\epsilon_i$ is common to all fermions of a given generation, thus inducing correlations among quark and lepton observables. For lepton flavor conserving (LFC) processes, only small deviations from SM predictions were found [2], reflecting the mutual constraints between the quark and lepton sectors, which preclude large discrepancies. On the other hand, the model allows tree-level lepton flavor violating (LFV) decays, yielding correlations between LFV $b\to s$ transitions and charged lepton decays. The analysis of such correlations shows that the current experimental upper bounds for the rates of $\tau^- \to \mu^-\mu^+\mu^-$, \ $\mu^-\to e^- \gamma$, \ $\mu^- \to e^- e^+e^-$ and $\mu^- \to e^-$ conversion in nuclei constrain branching ratios of LFV $B_{(s)}$ decays in hierarchical order [2].


[19] 2606.07411

Revisiting Time Evolution and Spatial Distribution of a Resonance

A resonance can be represented by the Gamow vector $|\psi^{\rm Gamow}\rangle$ in the complex momentum space $|\vec p e^{-i\theta}\rangle$. In this work we revisit its representation $|\psi^{\rm phys}\rangle$ in the real momentum space $|\vec p \rangle$ through the analytical continuation of Gamow wavefunction, which also satisfies with the Hamilton eigenequation with the assistance of a few discrete virtual state vectors whose kinetic energies are the complex eigenmass. Both the decreasing behavior of the resonance and the production of the decayed scattering states can be both simultaneously described by the time evolution $|\psi^{\rm phys},t\rangle=\exp(-iH t) \, |\psi^{\rm phys}\rangle$. The $|\psi^{\rm phys},t=0\rangle$ gives the finite-range confinement of the resonance while the $|\psi^{\rm phys},t\to +\infty\rangle$ provides a Breit-Wigner-like distribution of the final scattering states whose appearance probability is nonzero as $r\to \infty$. A toy model in hadron physics is used and numerically shows the above picture.


[20] 2606.07429

Interpolation between Sudakov and BFKL rapidity evolutions for TMD factorization at small $x$

Within the framework of rapidity-only small-$x$ TMD factorization, the evolution with respect to the rapidity cutoff is initially governed by Sudakov double logarithms and subsequently by BFKL/BK single logarithms. The evolution equation proposed in this paper correctly reproduces both the Sudakov and BFKL limits, while providing a consistent interpolation between these two regimes.


[21] 2606.06553

Hyperon-Nucleon Spectrometer

Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding $\Lambda$ polarization puzzle, in which $\Lambda$ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton ($pp$), proton-nucleus ($pA$), and nucleus-nucleus ($AA$) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of $pA$ and $AA$ collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.


[22] 2606.06581

Three Advanced Lectures on Inflation

Lecture notes on inflation. The lectures are three double lectures, held for the first time at the Nordita Winter School 2024 - Particle Physics and Cosmology, covering an advanced introduction to the theory of primordial inflation, as well as the linear and non-linear perturbation theory of slow-roll inflation/quasi-de Sitter spacetimes.


[23] 2606.07446

Polarized and unpolarized synchrotron emission from dark matter in extragalactic targets

We compute 95% confidence-level upper limits on the dark matter annihilation cross section and decay rate from both total-intensity and polarized synchrotron emission in five extragalactic targets: M31, the Large Magellanic Cloud (LMC), the Draco and Sculptor dwarf spheroidal galaxies, and the Coma cluster. Using Planck maps at 30, 44, and 70 GHz, we solve the diffusion-loss equation for dark-matter-produced electrons and positrons numerically with DRAGON and integrate the resulting synchrotron emission along the line of sight with HERMES, computing both total-intensity and polarized-intensity maps for each target with target-specific magnetic-field, gas, and radiation-field environments. The 30 GHz channel yields the most stringent constraints in all cases, and limits on annihilation or decay into $e^+e^-$ are stronger than those for $b\bar{b}$ due to the harder injected spectrum. For most targets the total-intensity and polarized limits are broadly comparable; the LMC is an exception, where Faraday depolarization in the turbulent disk suppresses the polarized signal relative to total intensity, making total intensity the primary estimator. Our results are robust against the choice of flux estimator and coordinate uncertainty. This work demonstrates that microwave polarimetry provides a complementary and largely independent probe of dark matter synchrotron emission in extragalactic targets.


[24] 2412.19694

Nonperturbative effects in triple-differential dijet and Z+jet production at the LHC

In comparisons of precision measurements at colliders to the most accurate predictions available in perturbative quantum chromodynamics (QCD), it is required to correct for nonperturbative effects. By means of Monte Carlo event generators this article investigates the impact of such nonperturbative effects on two processes relevant for precision determinations of the strong coupling constant and the proton structure: triple-differential dijet and Z+jet production. We observe significant differences between the two processes. Whether this non-universal behaviour is realized in nature remains an open question. We therefore propose a triple-differential measurement of the underlying event in Z+jet production.


[25] 2503.15609

Flavour and Electroweak Precision Constraints on a Simplified Dark Matter Model with a Light Spin-0 Mediator

This work investigates the allowed parameter spaces of a simplified dark matter (DM) model characterized by a spin-0 mediator with masses in the low to intermediate range ($ < $ 10 GeV). We systematically divide the parameter space into various mass regions of the mediator and constrain the model parameters using a diverse set of observables, including flavour-changing charged and neutral current processes such as rare and semi-leptonic decays of pseudoscalar mesons (B and K), electroweak precision observables, alongside data from fixed-target experiments. Additionally, we explore the model's capability to explain recent Belle-II data on invisible B-meson decays. Our study includes a detailed examination of DM properties and the constraints from Big Bang nucleosynthesis. We present bounds on model parameters through individual and simultaneous analyses of the available inputs and highlight their implications for understanding DM phenomenology. Furthermore, we obtain bounds on the couplings of the possible gauge-invariant dimension-5 operators, leading to the possible interactions between the spin-0 mediator and the SM gauge bosons and fermions. This study comprehensively investigates the constraints and theoretical implications associated with low-mass spin-0 mediator DM models.


[26] 2504.13259

The $β$-decay spectrum of Tritiated graphene: combining nuclear quantum mechanics with Density Functional Theory

We present the results of a multi-methodological study aimed at investigating the interaction between graphene and Tritium during its $\beta$-decay to Helium, under different levels of loading and geometrical configurations. We combine Density Functional Theory (DFT), to evaluate the interaction potentials, with calculations of the decay rate, in order to study the consequences that the presence of the substrate has on the $\beta$-decay spectrum of Tritium. We determine the shape of the event rate, accounting for the effects of (part of) the corresponding condensed matter degrees of freedom. In the context of future neutrino experiments, our results provide important information aimed at the optimization of hosting material, as well as the determination of the physics reach. Furthermore, our work outlines a novel theoretical and computational scheme to address a question at the boundary between high and low energy physics. This requires non-conventional declinations of DFT combined with full quantum treatments of the nuclear configuration involved in the decay process.


[27] 2511.07519

Jet quenching in out-of-equilibrium QCD matter

We present the first study of jet substructure modifications during the bottom-up evolution that describes the early stages of heavy-ion collisions. To this end, we study the bremsstrahlung radiation rate of soft gluons from a hard parton propagating through out-of-equilibrium QCD matter. The gluon spectrum is computed within the Improved Opacity Expansion, which accounts for both multiple soft and single hard momentum exchanges between the hard probe and the medium. The background evolution is obtained from effective kinetic theory simulations that determine the jet quenching parameter, which in turn controls the radiation rate. We compute the radiation rate for initially under- and over-occupied systems, as well as for an expanding system undergoing hydrodynamization, which typically represents the initial stages of heavy-ion collisions. The results for these dynamical backgrounds are compared to static and thermally matched scenarios, allowing to gauge the importance of bulk expansion in the evolution of the jet cascade. Our findings show that the early stages of the bulk matter evolution in heavy-ion collisions leave a sizable imprint on the radiation pattern inside jets. These results establish a basis for incorporating pre-equilibrium dynamics into realistic descriptions of jet quenching and hard-probe evolution.


[28] 2511.16052

Electromagnetic form factors: A window into the $DΛ_c$, $D^*Λ_c$, and $DΛ_c^*$ molecular structure

The internal structure of exotic hadrons remains one of the most compelling puzzles in strong interaction physics. In this work, we provide crucial insights into the nature of doubly-charmed pentaquarks by investigating their electromagnetic properties. Using QCD light-cone sum rules, we present the first comprehensive calculation of the magnetic dipole moments of $D\Lambda_c$, $D^*\Lambda_c$, and $D\Lambda_c^*$ molecular pentaquarks with $J^P = \frac{1}{2}^-$, $\frac{3}{2}^-$, and $\frac{3}{2}^-$, respectively. Our analysis reveals a striking hierarchy of magnetic moments: $\mu_{D\Lambda_c^*} > \mu_{D^*\Lambda_c} > \mu_{D\Lambda_c}$, driven by distinct quark-level mechanisms. While light quarks dominate the overall response, we find that charm quark contributions become strategically important when light quark contributions partially cancel. Beyond dipole moments, we predict higher multipoles--electric quadrupole and magnetic octupole moments--for the spin-$3/2$ $D^*\Lambda_c$ and $D\Lambda_c^*$ states, which fingerprint the spatial deformation of these configurations, revealing prolate versus oblate charge distributions. These results provide the first systematic predictions for electromagnetic moments of molecular pentaquark configurations, establishing essential benchmarks for future theoretical and experimental studies. By systematically comparing our predictions with both compact doubly-charmed and hidden-charm pentaquark configurations, we establish robust benchmarks that discriminate between competing structural models, ultimately resolving the nature of doubly-charmed exotic hadrons.


[29] 2512.19833

Universal Seesaw Leptogenesis

We study the implications for leptogenesis in a class of left-right symmetric model, where all fermion masses are induced through the Universal Seesaw mechanism. Unlike conventional analyses, we do not use the decays of the neutrino embedded in the right-chiral lepton doublet, but rather those of the gauge-singlet mediators required for neutrino mass generation in the canonical Type-I seesaw. This model features a generalized parity symmetry, which is motivated by the solution to the strong $CP$ problem. Since this discrete symmetry doubles the fermionic degrees of freedom in this model, we can generate the required $CP$ violation in the heavy fermion decays with only a single generation of mediators. One of the distinct features of our scenario is that the bounds from thermalization or washout via gauge interactions typically encountered in the canonical left-right symmetric models do not apply here. Moreover, the heavy mediators can decay to both the left and the right-chiral neutrinos, leading to a cancellation in the resulting baryon asymmetry for decays above the left-right symmetry breaking scale. We discuss ways to avoid this cancellation and show that low scale left-right symmetry breaking above the current collider limits $v_R > 18$ TeV is viable. The right chiral neutrinos also obtain their masses from the seesaw mechanism, and the lightest one turns out to have a sub-eV scale mass. We find that its abundance is consistent with standard cosmology, and it acts as potentially observable dark radiation.


[30] 2602.21872

Study of the $Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}$ dibaryons in QCD Sum Rules

The recent observation of a family of fully-charm tetraquark states by the LHCb, ATLAS and CMS Collaborations suggests the possible existence of fully-heavy dibaryons. In this work, we investigate the $\Omega_{ccc}\Omega_{ccc}$ and $\Omega_{bbb}\Omega_{bbb}$ dibaryons in both the $^1S_0$ and $^5S_2$ channels using the method of QCD sum rules. We employ the iterative dispersion relation (IDR) method to efficiently compute the massive five-loop banana diagrams that appear in these systems, and properly address the tricky small-circle divergence problem in the nonperturbative terms. Our analyses reveal that for both charm and bottom systems, the scalar dibaryon lies lower than its tensor counterpart. In $\overline{\text{MS}}$ scheme, the mass of the scalar $\Omega_{ccc}\Omega_{ccc}$ dibaryon is found to be slightly above the $2\Omega_{ccc}$ mass threshold, while the $\Omega_{bbb}\Omega_{bbb}$ systems may form bound states. However, they are predicted to be much heavier in the on-shell scheme.


[31] 2603.29803

Perturbative QCD fitting of KEDR and BESIII $e^+e^-$ data for R(s) and $α_s$ determination

The experimental data collected by KEDR and BESIII collaborations at the energies below charm quark thresholds are compared with the massless QCD expressions for the $e^+e^-$ annihilation R-ratio truncated at different orders of perturbation theory. The fits demonstrate the dependence of the extracted $\alpha_s(M_Z)$ values on the orders of truncation of the corresponding approximations. The next-to-leading order, next-to-next-to-leading order and next-to-next-to-next-to-leading order fits of the combined KEDR data and BESIII data , truncated at the scale of mass of $J/\Psi$ meson, give the following results $\alpha_s(M_Z)=0.1151_{-0.0069}^{+0.0052}$, $\alpha_s(M_Z)=0.1190_{-0.0081}^{+0.0064}$and $\alpha_s(M_Z)=0.1283_{-0.0075}^{+0.0028}$. The increasing tendency of fitted $\alpha_s(M_Z)$ value is associated with the effects of not totally controlled within asymptotic perturbation theory expansions kinematical $\pi^2$ contributions to R-ratio coefficients due to analytical continuation from the space-like to time-like energy regions. The applications of the fixed orders of perturbation theory expansions and careful treatment of the analytical continuation effects are commented.


[32] 2604.02607

Dual Implications of Quark Mass Hierarchies to Flavor Structure

To solve the mystery of flavor structure, we demonstrate two implications emerging from the hierarchical masses of quarks: one for the mass matrix itself and one for the CKM mixing. These implications naturally lead to a non-redundant, ordered, and family-unified quark flavor structure, which serves as a candidate to replace the unclear Yukawa interactions of the Standard Model.


[33] 2606.01178

Probing the imaginary parts and their $q^2$ dependences for the tau $g-2$ and EDM

The $\tau$ anomalous magnetic dipole moment (MDM) $a_\tau = (g-2)_\tau/2$ and electric dipole moment (EDM) $d_\tau$, are precision probes of electroweak dynamics and possible new physics sources, yet both remain weakly constrained experimentally. Treated as generalized form factors, these quantities exhibit a generic $q^2$ dependence for an off-shell interacting photon. For timelike momentum transfer above the $\tau^+\tau^-$ threshold, $q^2 = s > 4m_\tau^2$, the form factors can acquire absorptive imaginary parts. We investigate how such a $q^2$ dependence and the associated imaginary parts are generated from two complementary perspectives: the model-independent Standard Model Effective Field Theory (SMEFT) and a UV-complete Two-Higgs-Doublet Model (2HDM). The effective framework reveals the intimate correlation between $a_\tau$ and $d_\tau$. New CP-violating interactions which generate a non-zero $d_{\tau}$, can also generically have non-zero contributions to $a_\tau$, thereby deeply linking their phenomenological studies. Within the 2HDM, we demonstrate that sizable imaginary parts and significant $q^2$ running can be generated at levels accessible by $e^+e^-$ colliders. Motivated by these features, we propose experimental methods to extract both the real and imaginary components of the dipole form factors. Utilizing these techniques, we show that Belle II and the Super Tau-Charm Facility (STCF) can improve current bounds on $a_\tau$ by more than one order of magnitude. Finally, we highlight that combining measurements across the distinct center-of-mass energies of Belle II and STCF provides a unique, previously unexplored avenue to explicitly obtain information about the $q^2$ evolution of these dipole form factors.


[34] 2304.05793

Confronting fuzzy dark matter with the rotation curves of nearby dwarf irregular galaxies

We investigate phenomenologically the viability of fuzzy dark matter (FDM). We do this by confronting the predictions of the model, in particular, the formation of a solitonic core at the center of dark matter halos, with a homogeneous and robust sample of high-resolution rotation curves from the "LITTLE THINGS in 3D" catalog. This comprises a collection of isolated, dark matter dominated dwarf-irregular galaxies that provides an optimal benchmark for cosmological studies. We use a statistical framework based on Markov chain Monte Carlo techniques that allows us to extract relevant parameters such as the axion mass, the mass of the solitonic core, the mass of the dark matter halo and its concentration parameter with a rather loose set of priors except for the implementation of a core-halo relation that is predicted by simulations. The results of the fits are used to perform various diagnostics on the predictions of the model. FDM provides an excellent fit to the rotation curves of the "LITTLE THINGS in 3D" catalog, with axion masses determined from different galaxies clustering around $m_a\approx2\times10^{-23}$ eV. However, we find two major problems in our analysis. First, the data follow scaling relations of the properties of the core which are not consistent with the predictions of the soliton. This problem is particularly acute in the core radius - mass relation with a tension that, at face value, has a significance $\gtrsim5\sigma$. The second problem is related to the strong suppression of the linear power spectrum that is predicted by FDM for the axion mass preferred by the data. This can be constrained very conservatively by the galaxy counts in our sample, which leads to a tension exceeding again $5\sigma$. We estimate the effects of baryons in our analysis and discuss whether they could alleviate the tensions of the model with observations.


[35] 2504.03844

Simple third order operator-splitting schemes for stochastic mechanics and field theory

We present a method for constructing numerical schemes with up to 3rd strong convergence order for solution of a class of stochastic differential equations, including equations of the Langevin type. The construction proceeds in two stages. In the first stage one approximates the stochastic equation by a differential equation with smooth coefficients randomly sampled at each time step. In the second stage the resulting regular equation is solved with the conventional operator-splitting techniques. This separation renders the approach flexible, allowing one to freely combine the numerical techniques most suitable to the problem at hand. The approach applies to ordinary and partial stochastic differential equations. In the latter case, it naturally gives rise to pseudo-spectral algorithms. We numerically test the strong convergence of several schemes obtained with this method in mechanical examples. Application to partial differential equations is illustrated by real-time simulations of a scalar field with quartic self-interaction coupled to a heat bath. The simulations accurately reproduce the thermodynamic properties of the field and are used to explore dynamics of thermal false vacuum decay in the case of negative quartic coupling.


[36] 2508.04019

Graph theory-based automated quantum algorithm for efficient querying of acyclic and multiloop causal configurations

Quantum algorithms provide a promising framework in high-energy physics, in particular, for unraveling the causal configurations of multiloop Feynman diagrams by identifying Feynman propagators with qubits, a challenge analogous to querying directed acyclic graphs in graph theory. In this paper, we present the Minimum Clique-optimised quantum Algorithm (MCA), an automated quantum algorithm designed to efficiently query the causal structures within the Loop-Tree Duality. The MCA quantum algorithm is optimised by exploiting graph theory techniques, specifically, by analogy with the Minimum Clique Partition problem. The evaluation of the MCA quantum algorithm is exhibited by analysing the transpiled quantum circuit depth and quantum circuit area.


[37] 2511.05754

"Niñas Atómicas" (Atomic Girls): An initiative that generates opportunities for young girls in STEM

We report on an initiative that seeks to encourage high school girls to develop critical thinking and transferable skills widely used in scientific work, as well as to generate a concrete space of opportunities for girls to experience how real science is done. Our "Niñas Atómicas" workshop combines the teaching of particle physics, electronics, programming and scientific methodology through building and operating a dedicated experiment: a muon counter. Girls from all over Chile can apply to this workshop, where every year they are guided by female scientists for two weeks. We report on the contents and methodology of our workshop and provide details on how to build the muon detector. We report results on muon flux and proper lifetime, two muon properties which can be extracted from the data collected by the girls with the muon detectors they built themselves. Insights into the girl's experiences during the 2024 and 2025 editions of the workshop are also detailed, with the aim to contribute to the wider physics education research and outreach communities.


[38] 2511.13866

Large Scale White Noise and Cosmology

The generation of white noise on large scales is a generic property of the dynamics of physical systems described by local non-linear partial differential equations. Non-linearities prevent the small scale dynamics from being erased by smoothing. Unresolved small scale dynamics act as an uncorrelated (white or Poissonian) noise (seemingly stochastic but actually deterministic) contribution to large scale dynamics. This white noise exists even when the dynamics is very nearly linear. In cases where the power spectrum is sub-Poissonian on large scales, this noise will dominate on the largest scale power no matter the amplitude of the inhomogeneities. Such is the case in the standard model of cosmology, where the primordial density power spectrum is expected to have an almost Harrison-Zel'dovich, $P[k]\sim k$, spectrum on a much broader range of scales than can be observed. Even though linear gravitational evolution dominates non-linear corrections by a factor $\sim10^5$, the non-observation of white noise on the Hubble scale precludes the extrapolation of this power law below the comoving $1\,$pc scale. More generally, observation or non-observation of large scale white noise provides a powerful probe of the universe on very small scales in the early early universe. Gravitational radiation, phase transitions, vorticity, and running of the spectral index are all phenomena that can be probed with large scale white noise. Large scale white noise is a non-optional feature of all cosmological models but one which has not heretofore been appreciated.