Thu·Feb 5, 2026Thursday·February 5, 2026

1. 01*

   Ultralight time-oscillating scalars from magnetized compact stars: electrophilic radiation and photon propagation effects

   Tanmay kumar Poddar🇬🇧 · Gaetano Lambiase🇮🇹

   Ultralight scalars with electrophilic couplings to the time-dependent Goldreich-Julian charge density of magnetized compact stars can be radiated from their magnetospheres, contributing to pulsar spin-down. Coupling to the time-independent component of the charge density instead generates a quadrupolar scalar field profile, which may influence the orbital dynamics of binary systems. Such scalars can also interact with the time-varying electromagnetic fields of magnetized stars, modifying photon propagation and inducing observable effects in the redshift and residual time-delay measurements, as well as corrections to the background electromagnetic fields. We investigate these phenomena for the Crab pulsar, SGR 1806-20, and GRB 080805A. Using spectral and timing observations, we derive constraints on the scalar-electron and scalar-photon couplings. While the bounds obtained on the scalar-electron coupling from pulsar spin-down are weaker than existing limits, electromagnetic radiation measurements yield the strongest astrophysical constraints to date on the scalar-photon coupling. Compact stars with stronger surface magnetic fields and observations at lower photon frequencies can improve these bounds by several orders of magnitude.

   hep-phastro-ph.CO1 citation
2. 02*

   Quantum Entanglement and Bell Nonlocality at Future Lepton Collider

   Emidio Gabrielli🇮🇹 · Luca Marzola🇪🇪

   Quantum entanglement and Bell nonlocality--cornerstones of quantum mechanics--have traditionally been investigated only in low-energy experimental settings. Only recently, these fundamental phenomena have come to be explored in the high-energy domain of particle physics, where collider experiments offer a powerful new platform for studying the phenomenology of quantum correlations. We present here recent results on the detection of entanglement and Bell nonlocality in processes such as tau-lepton, $WW$, and $ZZ$ pair production, illustrating the potential of Future Lepton Colliders to probe the quantum properties of fundamental interactions.

   hep-phhep-exEur.Phys.J.Plus(2026)·10 citations
3. 03*

   Emergent equilibrium-like yields from nonequilibrium cascade dynamics

   Takeshi Fukuyama🇯🇵

   We study nonequilibrium cascades in which fragile bound or coherent structures are formed through intermediate states rather than by direct equilibration. Motivated by light-nuclei production in relativistic heavy-ion collisions and by Bose--Einstein condensation in cosmological settings, we analyze such processes within the Schwinger--Keldysh real-time formalism. We show that commonly used rate equations can be understood as a controlled Markovian approximation obtained by integrating out intermediate reservoirs in an underlying multi-component nonequilibrium dynamics. When the finite lifetime of these reservoirs is retained, non-Markovian memory effects naturally appear, leading to delayed and history-dependent formation dynamics. The associated memory time provides a quantitative criterion for the validity of reduced, rate-based descriptions far from equilibrium.

   hep-phnucl-thPRC(2026)·0 citations
4. 04*

   Disentangling baryon stopping and neutron skin effects in heavy-ion collisions

   Grégoire Pihan🇺🇸 · Volodymyr Vovchenko🇺🇸

   We analyse the net baryon (B) and net electric charge (Q) stopping in heavy-ion collisions using the statistical model. Focusing first on isobar collisions $\mathrm{Ru}+\mathrm{Ru}$ and $\mathrm{Zr}+\mathrm{Zr}$ at $\sqrt{s_{\mathrm{NN}}}=200$~GeV, we show that the excess baryon-stopping parameter ${\gamma }_B\equiv (N_B/N_Q)(Z/A)$ can be quantitatively extracted from forthcoming RHIC measurements of charge- and baryon-stopping ratios. We then generalize the approach to other collision systems at RHIC and LHC energies and introduce an oxygen-baseline observable, $r^{OX}$, whose central-to-peripheral ratio exhibits strong and systematic sensitivity to the neutron-skin thickness of the target nucleus $X$.

   hep-phnucl-exnucl-th2 citations
5. 05*

   Charmonium, exotic hadrons and hadron structure

   Bing-Song Zou🇨🇳

   To celebrate the 50th anniversary of the discovery of the J/{\psi}, the first charmonium state observed, I start with a brief review of major progresses on the QCD inspired quark potential model originated from charmonium spectrum.Then I show the importance of unquenching dynamics, multiquark components and exotic multiquark states for understanding hadron structure and hadron spectrscopy. The J/{\psi} and charmonium-like states have played an important role in this aspect.

   hep-phnucl-thNPB(2026)·2 citations
6. 06*

   Charged lepton flavor violating decays $Z\to {\ell }_{\alpha }{\ell }_{\beta }$ in the inverse seesaw

   Adrián González-Quiterio🇲🇽 · Héctor Novales-Sánchez🇲🇽

   After confirmation of massiveness and mixing of neutrinos, by neutrino oscillation data, the origin of neutrino mass and the occurrence of charged-lepton-flavor non-conservation in nature have become two main objectives for the physics of elementary particles. Taking inspiration from both matters, we address the decays $Z\to {\ell }_{\alpha }{\ell }_{\beta }$, with ${\ell }_{\alpha }\ne {\ell }_{\beta }$, thus violating charged-lepton flavor. We calculate the set of contributing one-loop diagrams characterized by virtual neutral leptons, both light and heavy, emerged from the inverse seesaw mechanism for the generation of neutrino mass. By neglecting charged-lepton and light-neutrino masses, and then assuming that the mass spectrum of the heavy neutral leptons is degenerate, we find that a relation $\text{Br}(Z\to {\ell }_{\alpha }{\ell }_{\beta })\propto |{\eta }_{\beta \alpha }{|}^2$, with $\eta$ the matrix describing non-unitarity effects in light-lepton mixing, is fulfilled. Our quantitative analysis, which considers both scenarios of degenerate and non-degenerate masses of heavy neutral leptons, takes into account upper bounds on ${\eta }_{\mu e}$, imposed by current constraints on the decay $\mu \to e\gamma$ from the MEG II experiment, while projected future sensitivity of this experiment is considered as well. We find that, even though current constraints on $Z\to {\ell }_{\alpha }{\ell }_{\beta }$, by the ATLAS Collaboration, remain far from inverse-seesaw contributions, improved sensitivity from in-plans machines, such as the Future Circular Collider and the Circular Electron Positron Collider, shall be able to probe this mass-generating mechanism through these decays.

   hep-ph0 citations
7. 07*

   Studies of the Roper Resonance by the Ljubljana Group

   Simon Sirca🇸🇮

   Ever since its discovery in 1964 the nature of the N*(1440) nucleon resonance has been a perpetual and one of the outstanding puzzles in hadronic physics. The Ljubljana group joined the global effort in the late 1990s, first from the theoretical viewpoint and later experimentally. This paper is a short overview of our attempts to understand this elusive resonance.

   hep-phActa Phys.Polon.B(2026)·0 citations
8. 08*

   Analysis of the semileptonic decays ${\Sigma }_b\to {\Sigma }_{c}l{\bar{\nu }}_l$, ${\Xi }_b^{\prime }\to {\Xi }_c^{\prime }l{\bar{\nu }}_l$ and ${\Omega }_b\to {\Omega }_{c}l{\bar{\nu }}_l$ in QCD sum rules

   Jie Lu🇨🇳 · Guo-Liang Yu🇨🇳 · Dian-Yong Chen🇨🇳 · Zhi-Gang Wang🇨🇳 · Bin Wu🇨🇳

   In this article, the electroweak transition form factors of ${\Sigma }_b\to {\Sigma }_c$, ${\Xi }_b^{\prime }\to {\Xi }_c^{\prime }$ and ${\Omega }_b\to {\Omega }_c$ are analyzed within the framework of three-point QCD sum rules. In phenomenological side, all possible couplings of interpolating current to hadronic states are considered, and the Dirac structure dependence on the form factors is systematically eliminated. In QCD side, our calculation incorporates both the perturbative part and the contributions from vacuum condensates up to dimension 8. This systematic inclusion of higher-dimensional terms accounts for a broader set of Feynman diagrams, thereby enhancing the comprehensiveness and reliability of the operator product expansion. Using the obtained form factors, we study the partial widths of semileptonic decays ${\Sigma }_b\to {\Sigma }_{c}l{\bar{\nu }}_l$, ${\Xi }_b^{\prime }\to {\Xi }_c^{\prime }l{\bar{\nu }}_l$ and ${\Omega }_b\to {\Omega }_{c}l{\bar{\nu }}_l$ ($l=e$, $\mu$ and $\tau$). The results indicate that these decay widths approximately satisfy SU(3) flavor symmetry. Next, we calculate the branching ratios for the decay process ${\Omega }_b\to {\Omega }_{c}l{\bar{\nu }}_l$ and compare them with the results from other collaborations. Furthermore, the lepton universality ratios and some asymmetry parameters of these decay processes are also analyzed, which provide information for the study of new physics. We hope that these results will serve as a useful reference for future theoretical and experimental studies of weak decays involving heavy flavor baryons.

   hep-phEPJC(2026)·2 citations
9. 09*

   Semileptonic decay form factors of ${\Xi }_b^0\to {\Xi }_c^{+}\ell {\bar{\nu }}_{\ell }$ in HQET

   Kinjal Patel🇮🇳 · Kaushal Thakkar🇮🇳

   Heavy-to-heavy semileptonic decays, particularly the bottom-to-charm quark transitions, are essential for testing the Standard Model (SM) and extracting the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. These decays have been extensively studied using various theoretical approaches. In this work, we investigate the semileptonic decay ${\Xi }_b^0\to {\Xi }_c^{+}\ell {\bar{\nu }}_{\ell }$ (where $\ell =e$, $\tau$) using a phenomenological quark model. We compute the ground-state masses of the initial and final baryons to get the wave function, which is then used to calculate the form factors, including corrections up to order $1/m_Q$ within the framework of Heavy Quark Effective Theory (HQET). The obtained form factors are implemented in the helicity formalism to evaluate the differential decay rates, total decay width and branching ratio. We compare our results for the form factors at both the maximum and minimum recoil points with previous theoretical studies, finding good agreement. We observe that the form factors depend on the transferred momentum $q^2$ and their magnitude gradually increases with increasing $q^2$. The dominant form factors are $f_1$ and $g_1$, and they also exhibit similar $q^2$ dependencies. Additionally, we calculate the lepton flavour universality (LFU) ratio $R({\Xi }_c)\approx 0.3$, which is in agreement with existing theoretical predictions.

   hep-phJ.Subatomic Part.Cosmol.(2026)·0 citations
10. 10*

    Heavy-quark production in deep-inelastic scattering -- Mellin moments of structure functions

    Marco Klann🇩🇪 · Sven-Olaf Moch🇩🇪 · Kay Schönwald🇨🇭

    We compute Mellin moments of the heavy-quark structure functions in deep-inelastic scattering at next-to-leading order in quantum chromodynamics, retaining their full dependence on the heavy-quark mass. Using the optical theorem and the operator product expansion, we derive analytic results for fixed Mellin moments $N=2$ to $22$ of the structure functions $F_2$ and $F_L$. Our results reproduce the known expressions in the relevant asymptotic limits, in particular for virtualities of the exchanged photon $Q^2$ much larger than the heavy-quark mass squared $m^2$, and are in agreement with existing parametrisations of the next-to-leading-order coefficient functions. The computational set-up developed in this work also provides a direct pathway toward extending these calculations to next-to-next-to-leading order.

    hep-phNPB(2026)·2 citations
11. 11*

    The EP Model and its Completion Terms (E4)

    J. A. Dixon🇨🇦

    Here we present the simple example of an Exotic Invariant with just two chiral electron supermultiplets E and P. In this example we include a mass term, and that means that there is a constraint on the Exotic Invariant. The constraint is easily solved for this simple case. Here we also exhibit a simple conjecture for the Completion Terms. This simple example is very useful, because the constraint that arises in the case of the Exotic Model, presented in E6, is just as easy to solve, and the Completion Terms there are also very similar to those here. So this simple EP model is very useful for understanding the Exotic Model, which is what results from adding an Exotic Invariant to the rather complicated Supersymmetric Standard Model.

    hep-phhep-th1 citation
12. 12*

    Searches for Extra Higgs Bosons using $t\bar{t}+$Higgs{{$(\to b\bar{b})$}} Events within 2HDMs: Direct versus Indirect Probes

    Esteban Chalbaud🇵🇹 · Stefania De Curtis🇮🇹 · Luigi Delle Rose🇮🇹 · Atri Dey🇸🇪 · Stefano Moretti🇬🇧 · Antonio Onofre🇵🇹

    We study the possibility of establishing the production of additional Higgs states in the process $gg,q\bar{q}\to t\bar{t}\Phi$, where $\Phi$ = $H_{2,3}$, with $H_2$ being CP-even and $H_3$ being CP-odd, at the Large Hadron Collider (LHC), by solely exploiting the kinematic features of the reconstructed $t\bar{t}$ system. We adopt as reference theoretical framework a generic CP-Conserving 2-Higgs Doublet Model (2HDM), which also accommodate a Standard Model (SM)-like Higgs state $H_1$. We show that the masses $m_{H_{2,3}}$ exhibit clear correlations with the $t\bar{t}$ system properties and could, in principle, be extracted from these. Moreover, the CP properties of the $H_{2,3}$ states can be determined, even when both states are produced simultaneously. We then compare the results produced using this method with those obtained from a full kinematic reconstruction of the $H_{2,3}$ decays in the most studied $b\bar{b}$ channel (we take $m_{H_{2,3}}<2m_t$), thus proving the superiority of the approach here proposed. This paves the way to both the discovery and characterization of additional Higgs states produced {\sl inclusively} in association with top-antitop quark pairs, thereby dispensing of the complications intrinsic to the {\sl exclusive} reconstruction of such states from their decay products. We test this by establishing the sensitivity of our approach in the case of a Composite 2HDM (C2HDM), describing the Higges as pseudo-Nambu Goldstone Bosons (pNGBs) and naturally predicting Higgs mass spectra in the range of sensitivity of the described analysis.

    hep-phhep-ex0 citations
13. 13*

    Fierz analyses on the decay properties of two- and three-gluon glueballs

    Wei-Han Tan🇨🇳 · Hua-Xing Chen🇨🇳

    The Fierz rearrangement, based on the various internal symmetries of hadrons, can be used to study their decay properties in a largely model-independent way. In this Letter we apply this method to calculate the relative branching ratios of two-gluon glueballs with $J^{PC}=0^{++}/0^{-+}$ and three-gluon glueballs with $J^{PC}=0^{++}/1^{+-}$. In total, we derive nearly one hundred ratios for these glueballs. Our results suggest that the $f_0(1710)$ and $\eta (2370)$ likely contain a significant gluon component, whereas the gluon component in $f_0(1500)$ appears to be small. Furthermore, we propose observing the three-gluon glueball with $J^{PC}=0^{++}$ in the $\pi \pi \omega$ and $K\bar{K}\varphi$ channels, and the three-gluon glueball with $J^{PC}=1^{+-}$ in the $\pi \pi \omega$, $\pi \pi \varphi$, and $K\bar{K}\varphi$ channels. This study enhances our understanding of the gluonic structure of exotic hadrons and will assist future experimental searches in high-energy physics.

    hep-phPRD(2026)·2 citations
14. 14*

    Fluctuation-Induced Friction in Bubble-Wall Dynamics of Cosmological First-Order Phase Transitions

    Dongdong Wei🇨🇳 · Zong-Kuan Guo🇨🇳

    We study bubble-wall dynamics in cosmological first-order phase transitions in a two-scalar-field model, where the wall is formed by $\varphi$ and an additional real scalar $s$ couples through a portal interaction. We evolve the coupled classical field equations on the lattice and demonstrate that for an initial Bose--Einstein distribution of $s$ fluctuations at the nucleation temperature $T_n$, the resulting patchy background intermittently modulates the local driving pressure on the wall. The wall therefore undergoes alternating episodes of acceleration and deceleration and approaches a quasi-stationary propagation regime with a smaller time-averaged speed than in the decoupled limit. We further identify three familiar propagation profiles -- deflagration, detonation, and hybrid -- distinguished by where the dynamical $s$-sector energy density is concentrated relative to the wall. These effects can impact gravitational wave and baryogenesis predictions.

    hep-ph0 citations
15. 15*

    Estimating power corrections for the Drell-Yan Process

    Ekta Chaubey🇩🇪 · Pooja Mukherjee🇩🇪

    We study power corrections in the Drell-Yan (DY) process using state-of-the-art predictions for both neutral and charged current production. For both types of DY processes, we account for power corrections arising from bottom and charm quark effects within a variable flavor number scheme. Our results show that these corrections become significant in the low-$Q$ region. We also ensure proper treatment of overlapping contributions by carefully applying matching procedures to eliminate any double counting.

    hep-phEur.Phys.J.ST(2026)·0 citations
16. 16*

    Relativistic and Recoil Corrections to Light-Fermion Vacuum Polarization for Bound Systems of Spin-0, Spin-1/2, and Spin-1 Particles

    G. S. Adkins🇺🇸 · U. D. Jentschura🇺🇸

    In bound systems whose constituent particles are heavier than the electron, the dominant radiative correction to energy levels is given by light-fermion (electronic) vacuum polarization. In consequence, relativistic and recoil corrections to the one-loop vacuum-polarization correction are phenomenologically relevant. Here, we generalize the treatment, previously accomplished for systems with orbiting muons, to bound systems of constituents with more general spins: spin-0, spin-1/2, and spin-1. We discuss the application of our more general expressions to various systems of interest, including spinless systems (pionium), muonic hydrogen and deuterium, and devote special attention to the excited non-S states of deuteronium, the bound system of a deuteron and its antiparticle. The obtained energy corrections are of order alpha^5*m_r, where alpha is the fine-structure constant and m_r is the reduced mass.

    hep-phPRD(2026)·1 citation
17. 17*

    Near-Resonant Thermal Leptogenesis

    Angus Spalding🇬🇧

    We study leptogenesis in the quasi-degenerate but non-resonant regime. Expanding the CP asymmetry parameter near degeneracy and imposing the conservative non-resonance condition that the mass splitting must be much greater than the right-handed neutrino decay rates $\Delta M>100{\Gamma }_i$, yields the universal upper bound $ϵ\le 1/200$, independent of both the effective neutrino masses and the right-handed neutrino mass. We investigate vanilla and flavoured near-resonant leptogenesis and find that successful leptogenesis by right-handed neutrino decays can occur for $M\gtrsim 100\mathrm{GeV}$ independent of washout regime, extending the viable parameter space of thermal leptogenesis down to the electroweak scale without invoking resonance. We also analyse near-resonant thermal leptogenesis during reheating and show that successful baryon asymmetry generation is compatible with reheating temperatures as low as $T_{RH}\simeq 10\mathrm{GeV}$ without relying on non-thermal production. Finally, we present a consistent framework for incorporating flavour effects in near-resonant leptogenesis during reheating. Overall, near-resonant thermal leptogenesis offers a controlled alternative regime to resonant leptogenesis, lowering the leptogenesis scale to the electroweak scale, without reliance on a disputed regulator used in resonant leptogenesis.

    hep-phastro-ph.COJHEP(2026)·2 citations
18. 18*

    Exploring supernova neutrino mass ordering at DUNE via quantum entanglement

    Adikiran Johny🇮🇳 · Athulkrishna R · Rudra Majhi🇮🇳 · Suchismita Sahoo🇮🇳

    The Deep Underground Neutrino Experiment (DUNE) offers strong sensitivity to neutrinos from a Galactic core collapse supernova, providing a powerful probe of neutrino flavor conversion and the neutrino mass ordering. In this work, we study supernova neutrino oscillations at DUNE using quantum entanglement as an organizing framework. Treating the three flavor neutrino system as an effective multipartite quantum state, we quantify flavor correlations through the entanglement of formation, concurrence, and negativity, expressed directly in terms of flavor survival and transition probabilities. Benchmark scenarios defined by representative variations of the electron neutrino survival probability are constructed for each entanglement measure. Event rates and fluences are computed for a supernova at 10 kpc, and the mass ordering sensitivity is evaluated using detector-level simulations performed with the \texttt{SNOwGLoBES} framework, employing the Garching supernova flux model and including the dominant detection channels in liquid argon: ${\nu }_e$ and ${\bar{\nu }}_e$ charged-current interactions on argon and elastic scattering on electrons. We analyze both individual and combined detection channels and incorporate $5\%$ normalization and energy calibration systematic uncertainties. Our results show that DUNE achieves a $5\sigma$ determination of the neutrino mass ordering for a supernova at distances of $\sim 20$~kpc for the ${\nu }_e$ charged current channel and $\sim 2$~kpc for the ${\bar{\nu }}_e$ channel, with the reach depending on the entanglement scenario considered. These results demonstrate that entanglement based observables provide a complementary and robust framework for probing supernova neutrino oscillations and the neutrino mass ordering.

    hep-ph1 citation
19. 19*

    Primordial black holes as cosmic accelerators of light dark matter: Novel direct detection constraints

    Sk Jeesun🇨🇳 · Anirban Majumdar🇮🇳 · Rahul Srivastava🇮🇳

    Current multi-tonne-scale dark matter (DM) detectors are largely incapable of detecting light dark matter from the Galactic halo due to the energy threshold limitations of their recoil measurements. However, primordial black holes (PBHs) can evaporate via Hawking radiation to particles whose energies are set by the black hole temperature. Consequently, weakly interacting light dark matter (or dark radiation) particles produced in this manner can reach the Earth with sufficient flux and kinetic energy above the experimental thresholds. This opens up a novel avenue to probe the light dark sector in terrestrial experiments. In this work, we explore this possibility by considering fermionic DM produced through PBH evaporation and investigating its electron recoil signatures in direct detection experiments. We analyze both energy independent (constant) and energy dependent (scalar and vector mediated) DM-electron interactions, highlighting the strong dependence of the recoil spectra on the underlying Lorentz structure of the interaction. In addition, we also account for the attenuation effects due to the loss of kinetic energy while DM traverses through Earth's crust, which can significantly modify the incoming DM flux. Incorporating these effects carefully, we place constraints on light DM using the electron recoil data from XENONnT, LZ, and PandaX-4T. Finally, we also discuss the detection prospects of such dark matter in current and future generation neutrino detectors, such as Super-Kamiokande and Hyper-Kamiokande.

    hep-phastro-ph.COhep-exJCAP(2026)·2 citations
20. 20*

    On the importance of radiation-era initial conditions for tensor perturbations

    Dražen Glavan🇨🇿 · Juraj Klarić🇳🇱 · Philipp Klose🇳🇱 · Ignacy Sawicki🇨🇿

    Conservation of super-horizon tensor fluctuations is crucial for connecting inflation to observations. Starting from first principles, recent works have found violations of this conservation if free-streaming radiation is produced during reheating. We show that the non-conservation is sensitive to the radiation initial state, and argue that the physical state should be affected by tensor perturbations that are already present during reheating. The deviation from super-horizon conservation is then negligible, recovering the standard result from kinetic theory. In contrast, a globally homogeneous and isotropic plasma state leads to a large suppression of tensor amplitudes. This difference between the local (physical) and global thermal equilibrium settles the discrepancy between the older and recent literature.

    ↳ hep-thgr-qchep-phJHEP(2026)·2 citations
21. 21*

    A simple mechanism for the enhancement of the inflationary power spectrum

    I. Dalianis🇨🇾 · A. Katsis🇬🇷 · N. Tetradis🇬🇷

    The background evolution in two-field inflation can feature two distinct stages, corresponding to the evolution along two successive field directions. When the second stage occurs at a significantly lower energy scale, the inflationary trajectory includes a sharp transition, accompanied by a series of rapid turns in field space. Fluctuations crossing the Hubble horizon during this turning phase can experience amplification by several orders of magnitude. This mechanism is very intuitive and can be implemented even in simple two-field models. It produces a peak in the scalar power spectrum that can lead to significant abundances of primordial black holes and secondary gravitational waves.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2026)·2 citations
22. 22*

    Mapping Nuclear Deformation with Differential Radial Flow in Heavy-Ion Collisions

    Jie Zhu🇨🇳 · Xiang-Yu Wu🇨🇦 · Guang-You Qin🇨🇳

    In relativistic heavy-ion collisions, the radial flow of the fireball, usually characterized by transverse momentum spectra of final-state particles, encodes essential information about the hot and dense nuclear matter created in the collisions. However, the response of radial flow, including its $p_T$-differential structure $v_0(p_T)$ and longitudinal fluctuations $v_0(\eta )$, to intrinsic nuclear deformation remains unexplored. Using realistic $(3+1)$-dimensional viscous hydrodynamic calculations with Trento-3D initial conditions, we investigate how nuclear deformation affects the differential radial flow. We observe a clear, positive correlation between quadrupole deformation ${\beta }_2$ and radial flow: both magnitudes of $v_0$ and $v_0(p_T)$ are enhanced in central collisions when ${\beta }_2$ is increased. In contrast, the Pearson coefficient $\rho (n(p_T),[p_T])$ exhibits a universal step-like behavior across all collision systems and centralities. Further analysis of longitudinal decorrelation of radial flow reveals a rich structure: in central collisions, large ${\beta }_2$ tends to suppress the decorrelation, whereas hexadecapole deformation ${\beta }_4$ tends to enhance it. Such decorrelation effect increases toward peripheral collisions. Our results demonstrate that precise measurements of radial flow, spanning transverse momentum and longitudinal dependences, can provide powerful, complementary constraints on nuclear deformation in high-energy nucleus-nucleus collisions.

    ↳ nucl-thhep-phnucl-exSCPMA(2026)·3 citations
23. 23*

    Parametric Resonance and Backreaction Effects in Magnetogenesis from Ultralight Dark Matter

    Nirmalya Brahma🇨🇦 · Robert Brandenberger (McGill University)🇨🇦

    We take a more detailed look at the recently proposed magnetogenesis mechanism triggered by ultralight dark matter coupled to electromagnetism. The proposed mechanism made use of a tachyonic resonance channel which leads to the exponential amplification of infrared modes. Here, we first investigate a possible narrow band parametric resonance channel which can produce photons at higher frequencies. Secondly, we estimate the effects of back-reaction on terminating the resonance. We find that there is indeed a narrow resonance channel. It is characterized by a Floquet exponent which is slightly smaller than the corresponding exponent for the tachyonic resonance. However, there is a region of parameter space (corresponding to a very small coupling constant) for which the tachyonic resonance is ineffective. In this case, the narrow resonance will dominate, and it will still be sufficiently strong to generate the observed magnetic fields on cosmological scales. Our analytical treatment of the back-reaction effects considered here indicates that a fraction of order one of the initial dark matter density can flow into the gauge fields. Hence, our magnetogenesis scenario appears to be robust to back-reaction effects.

    ↳ astro-ph.COgr-qchep-phhep-th7 citations
24. 24*

    Canonical differential equations beyond polylogs

    Claude Duhr🇩🇪 · Sara Maggio🇩🇪 · Christoph Nega🇩🇪 · Benjamin Sauer🇩🇪 · Lorenzo Tancredi🇩🇪 · Fabian J. Wagner🇩🇪

    Feynman integrals whose associated geometries extend beyond the Riemann sphere, such as elliptic curves and Calabi-Yau varieties, are increasingly relevant in modern precision calculations. They arise not only in collider cross-section calculations, but also in the post-Minkowskian expansion of gravitational-wave scattering. A powerful approach to compute integrals of this type is via differential equations, particularly when cast in a canonical form, which simplifies their $\epsilon$-expansion and makes analytic properties manifest. In these proceedings, we will present a method to systematically construct canonical differential equations even for integrals that evaluate beyond multiple polylogarithms. The discussion is kept as light as possible, focusing on the two-loop sunrise integral, deferring the technical details to the original publications.

    ↳ hep-thhep-ph1 citation
25. 25*

    From Florence to Fermions: a historical reconstruction of the origins of Fermi's statistics one hundred years later

    Roberto Casalbuoni · Daniele Dominici

    Aim of this paper is to retrace the path that led the young Enrico Fermi to write his paper on the statistics of an ideal monatomic gas. This discovery originated in his interest, which he had shown since his formative years, in the absolute entropy constant and in the problems he highlighted in Sommerfeld's quantization in the case of identical particle systems. The fundamental step taken by Fermi in writing his work on statistics was to apply the Exclusion Principle, formulated for electrons in an atom and which could therefore have been a pure effect due to dynamics, to a system of non-interacting particles.

    ↳ physics.hist-phhep-phhep-thquant-phEur.Phys.J.H(2026)·0 citations
26. 26*

    Benchmark Study of CEvNS Nuclear Recoil Observables for B, Mg, Ti, and Zr Targets Using Geant4

    Yusuf Havvat🇹🇷

    Coherent elastic neutrino-nucleus scattering (CEvNS) provides a well-defined framework for studying nuclear recoil observables in low-energy neutrino interactions. In this work, we present a comparative Monte Carlo benchmark study of CEvNS-induced nuclear recoils for four target nuclei (B, Mg, Ti, and Zr) using the Geant4 simulation toolkit and the ROOT analysis framework. The study focuses on relative differences in recoil-energy spectra, nuclear form-factor effects, and angular distributions under identical simulation conditions. A deliberately simplified detector geometry is employed to ensure a controlled and transparent comparison between target materials, rather than to model a specific experimental setup. The results highlight how nuclear mass and form-factor suppression influence CEvNS recoil observables and provide a reference-level comparison that may be useful for material-selection studies in CEvNS-related simulations.

    ↳ hep-exhep-ph1 citation
27. 27*

    Oort Cloud Bombardment by Dark Matter

    Jeremy Mould

    The realization that primordial black holes (PBHs) might be some fraction of the dark matter begged the question, how often do PBHs enter the solar system? For a Neptune radius solar system the answer is, rarely. For an Oort cloud sized system the answer is different. Simulations of bombardment of the Oort cloud by dark matter suggest that dislodgement of protocomets and their entry into the inner solar system can match the observed frequency of comets, if that PBH fraction is high enough. Comets were traditionally considered as messengers, usually omens. After 50 years of puzzlement regarding dark matter, we need a hint from the dark universe about the size and nature of dark matter particles.

    ↳ astro-ph.COastro-ph.EPastro-ph.SRhep-ph0 citations
28. 28*

    Stable Causality and Microcausality for Drummond-Hathrell Photons

    Madhukar Deb🇮🇳 · Jay Desai🇮🇳 · Diptimoy Ghosh🇮🇳

    Local superluminal photon propagation arises at $\mathcal{O}(\alpha /m_e^2)$ in the Drummond Hathrell (DH) effective action obtained by integrating out the electron in QED coupled to gravity. Whether such superluminality implies a genuine violation of causality in curved spacetime is subtle and remains conceptually nontrivial. In this work we revisit this question using two complementary and largely symmetry-independent diagnostics. First, we analyse the global causal structure of the effective (optical) metric governing DH photon propagation and identify conditions under which it remains stably causal, thereby excluding the formation of closed causal curves. Second, from a quantum-field-theoretic perspective, we examine microcausality by treating the gravitational background as a fixed Lorentz-breaking field and applying flat-spacetime analyticity bounds to the photon commutator within the geometric-optics regime of the EFT. For two representative examples, a circular photon orbit in Schwarzschild and a linear trajectory in a two-black-hole geometry, we find that, within the regime of validity of the DH effective theory, both diagnostics indicate that the superluminal photon propagation is causally benign. Our results do not constitute a general definition of microcausality in curved spacetime, but provide a controlled and instructive check of causal consistency for EFT superluminality in gravitational backgrounds.

    ↳ hep-thgr-qchep-phJHEP(2026)·2 citations
29. 29*

    Diffusion Models for SU(2) Lattice Gauge Theory in Two Dimensions

    H. Alharazin🇩🇪 · J. Yu. Panteleeva🇩🇪 · B.-D. Sun🇩🇪

    We apply score-based diffusion models to two-dimensional SU(2) lattice pure gauge theory with the Wilson action, extending recent work on U(1) gauge theories. The SU(2) manifold structure is handled through a quaternion parameterization. The model is trained on 10,000 configurations generated via Hybrid Monte Carlo at a fixed coupling ${\beta }_0=2.0$ on an $8\times 8$ lattice, augmented to 20,000 samples via random gauge transformations. Through physics-conditioned sampling exploiting the linear $\beta$-dependence of the score function, we generate configurations at different values of the coupling without retraining; through the fully convolutional U-Net architecture with periodic boundary conditions, we generate configurations on lattices of different spatial extents. We validate our approach by comparing the average plaquette against exact analytical predictions. At the training lattice size ($8\times 8$), the model reproduces the exact plaquette with biases $|\Delta |\le 0.001$ for $\beta \in [1.5,2.5]$ and $|\Delta |<0.06$ across $\beta \in [1,4]$. For lattices sharing the training extent $L=8$ in at least one direction, biases remain below $\sim 0.003$ for $\beta \in [1.5,2.5]$, with larger deviations at higher couplings. This work demonstrates that diffusion models are a promising tool for non-Abelian gauge field generation and motivates further investigation toward higher-dimensional theories.

    ↳ hep-lathep-phPRD(2026)·10 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.