Thu·Feb 12, 2026Thursday·February 12, 2026

1. 01*

   Gravitational scalar production with a generic reheating scenario

   Francesco Costa🇮🇪 · Jinsu Kim🇨🇳

   Gravitational production of decoupled scalars during inflationary and post-inflationary phases is efficient and can lead to over-production. We study this production with various reheating scenarios such as a generic power-law inflaton potential $V_{\inf }\propto {\varphi }^k$ as well as a multi-stage reheating scenario. We derive constraints on the scalar self-interaction coupling ${\lambda }_s$, the mass $m_s$, and coefficients of quantum gravity-induced operators. We find that the constraints depend sensitively on the reheating dynamics. Our analysis demonstrates that universal gravity effects do not necessarily spoil the predictivity of non-thermal dark matter scenarios with $k<4$ and low reheating temperatures, as an extended reheating phase dilutes gravitationally-produced relics. For $k>4$, on the other hand, the relic abundance is enhanced during the reheating phase, leading to stringent constraints on the scalar. In multi-stage reheating, we show that the enhancement/dilution effect of subsequent reheating phases factorises.

   hep-phastro-ph.COJHEP(2026)·1 citation
2. 02*

   The complete three-loop unpolarized and polarized massive operator matrix elements and asymptotic Wilson coefficients

   J. Ablinger🇦🇹 · A. Behring🇩🇪 · J. Blümlein🇩🇪 · A. De Freitas🇦🇹 · A. von Manteuffel🇩🇪 · C. Schneider🇦🇹 · K. Schönwald🇨🇭

   We report on the three-loop unpolarized and polarized massive operator matrix elements, with single- and two-mass corrections, and the associated deep-inelastic massive Wilson coefficients in the region $Q^2\gg m_Q^2$, the calculation of which has been completed recently. We also provide fast and precise numerical representations of the massless Wilson coefficients, splitting functions to tree-loop order, and target-mass corrections in $x$-space well suited for QCD-fitting codes.

   hep-phhep-exPoS(2025)·1 citation
3. 03*

   Manipulating Bell nonlocality and entanglement in polarized electron-positron annihilation

   Hong-Wei Zhang🇨🇳 · Xu Cao🇨🇳 · Tai-Fu Feng🇨🇳

   The hyperon-antihyperon pairs produced in electron-positron annihilation as a massive two-qubit quantum system can be used to study the quantum correlations at high energies. This paper is theoretically dedicated to how polarization of lepton beams manipulate the Bell nonlocality and entanglement of hyperon pairs system. The response of CHSH parameter, concurrence, and negativity to the polarization degree of beam is numerically calculated by exploiting the joint spin density matrix of hyperon-antihyperon pairs. Different influences of longitudinal and transverse polarization of beams on entanglement are found and compared. The results provide alternative perspectives for the decay of charmonium to hyperon pairs.

   hep-phPRD(2026)·21 citations
4. 04*

   Entanglement redistribution of hyperon-antihyperon pair via sequential decay

   Cong Li🇨🇳 · Xu Cao🇨🇳 · Ai-Qiang Guo🇨🇳 · Chun-Xu Yu🇨🇳 · Hong-Wei Zhang🇨🇳 · Zhe Zhang🇨🇳

   Hyperon-antihyperon pairs produced in high energy electron-positron annihilation constitute a naturally spin-entangled system in the high energy regime. Recently, a probabilistic amplification of entanglement, termed autodistillation, has been found in the daughter baryon-antibaryon pairs from hyperon decay and is constrained by an upper boundary. This work demonstrates that the quantum entanglement in this process may be accompanied by a decrease, constrained by a lower boundary, but will not be completely lost. Thus, the entanglement of these systems undergoes redistribution within the phase space during the sequential decays of hyperons, highlighting an important role of hyperon polarization. By using the explicit spin density matrix of baryon pairs, it is also found that quantumness of the system characterized by quantum discord always have the possibility to increase during decay processes, even when entanglement evaluated by concurrence and negativity does not increase.

   hep-phCPC(2026)·6 citations
5. 05*

   Unidentified falling objects in the LHC as dark matter signals

   Xunyu Liang🇨🇦 · Ariel Zhitnitsky🇨🇦

   Unidentified Falling Objects (UFOs) refer to sporadic beam losses observed during LHC operation. The prevailing explanation is that micrometer-sized dust particles released from the beam screen produce beam losses through interactions with the protons. However, the release mechanism of these particles remains unknown. We propose that roughly $(1-10)$% of UFOs may be caused by axion quark nuggets (AQNs), macroscopic dark matter (DM) candidates with masses of order $(5-1000)$g. The AQN model naturally relates the dark- and visible-matter abundances (${\Omega }_{\mathrm{DM}}\sim {\Omega }_{\mathrm{visible}}$) and provides a mechanism for generating the baryon-antibaryon asymmetry, with DM composed of both matter and antimatter AQNs. When passing underground within approximately 100km of the LHC, an antimatter AQN generates acoustic waves strong enough to trigger multiple UFO events within $2$s. If three correlated UFOs (placed at different locations along the LHC ring) are detected, the signal-to-noise ratio can exceed 5 across the entire allowed AQN mass range for a measurement time of about 360 hours. Practically, the LHC can serve as a large broadband acoustic detector for AQNs.

   hep-phastro-ph.IMhep-exphysics.acc-phPRD(2026)·4 citations
6. 06*

   Structural dissection of hadronic molecules: The $D^{(\ast )}{\bar{K}}^{(\ast )}$ family under QCD light-cone sum rules

   Ulaş Özdem🇹🇷

   We investigate the static electromagnetic properties of three charm--strange molecular tetraquark candidates with quantum numbers $J^P=1^{+}$, namely the $D{\bar{K}}^{\ast }$, $D^{\ast }\bar{K}$, and $D^{\ast }{\bar{K}}^{\ast }$ systems. The analysis is carried out within the framework of QCD light-cone sum rules, using interpolating currents constructed from colour-singlet meson bilinears to reflect their molecular configurations. Both perturbative and non-perturbative photon contributions are included,and numerical predictions for the magnetic and electric quadrupole moments are obtained. The magnetic moments are found to lie in the range $1$--$3$ nuclear magnetons, with the largest value associated with the $D^{\ast }\bar{K}$ configuration. The quadrupole moments are an order of magnitude smaller, of order $10^{-3}{\mathrm{fm}}^2$, indicating only weak deviations from spherical charge distributions. A flavour decomposition shows that the magnetic response is dominated by the light quarks, while the charm-quark contribution is strongly suppressed, a feature naturally expected for loosely bound hadronic molecules. The present analysis extends QCD light-cone sum-rule studies of exotic hadrons by providing a systematic determination of the electromagnetic moments of the $D^{(\ast )}{\bar{K}}^{(\ast )}$ molecular systems. These results provide quantitative benchmarks that may help discriminate between molecular configurations and more compact multiquark interpretations and may offer useful guidance for future experimental studies of electromagnetic signatures of charm--strange exotic states.

   hep-phhep-exhep-latPTEP·3 citations
7. 07*

   A fast Bayesian surrogate for the photon flux in ultra-peripheral collisions

   Simone Ragoni🇺🇸 · Janet Seger🇺🇸

   We present a fast surrogate for the Equivalent Photon Approximation (EPA) flux in ultraperipheral collisions (UPCs), based on a Bayesian neural network (BNN) trained over analytical flux integrals with an iterative procedure focused on regions of high relative uncertainties to minimise the number of integrations. The surrogate propagates experimentally available uncertainties on the neutron skin thickness and surface diffuseness. Once trained, this surrogate technique brings an estimated gain of two orders of magnitude in CPU time. The implementation provides a modular framework for rapidly propagating updated nuclear priors and assessing uncertainties for photon flux in future UPC analyses.

   hep-ph0 citations
8. 08*

   Unified Description of Pseudoscalar Meson Structure from Light to Heavy Quarks

   B. Almeida-Zamora🇲🇽 · L. Albino🇲🇽 · A. Bashir🇪🇸 · J.J. Cobos-Martínez🇲🇽 · J. Segovia🇪🇸

   We present a comprehensive review of the structure of pseudoscalar mesons within an algebraic model formulated in the light-front framework. The approach provides a unified description of leading-twist parton distribution amplitudes (PDAs), light-front wave functions (LFWFs), generalized parton distributions (GPDs), parton distribution functions (PDFs), elastic electromagnetic form factors (EFFs), charge radii, and impact-parameter GPDs (IPS-GPDs), all derived consistently from the same underlying Bethe-Salpeter amplitudes. Results are discussed for light ($\pi$, $K$), heavy-light ($D$, $D_s$, $B$, $B_s$, $B_c$), and heavy-heavy (${\eta }_c$, ${\eta }_b$) pseudoscalar mesons, allowing for a systematic analysis of the role played by quark-mass asymmetry and heavy-quark dynamics. The study highlights how increasing quark masses drive a transition from broad, asymmetric momentum distributions to increasingly symmetric and spatially compact configurations. Comparisons with lattice QCD, Dyson-Schwinger equation studies, and contact-interaction models are presented where available. Overall, the algebraic model offers a transparent and symmetry-consistent framework to explore the three-dimensional momentum and spatial structure of pseudoscalar mesons across all quark-mass regimes.

   hep-phhep-exhep-latnucl-ex+1Symmetry(2026)·2 citations
9. 09*

   A multidimensional landscape of the $\eta$ and ${\eta }^{\prime }$ mesons

   L. Albino🇪🇸 · K. Raya🇪🇸 · R. J. Hernández-Pinto🇲🇽 · B. Almeida-Zamora🇲🇽 · J. Segovia🇪🇸 · A. Huet🇲🇽 · A. Bashir🇪🇸

   We employ a recently proposed form-invariant algebraic model for the quark propagator and the Bethe-Salpeter amplitude of pseudoscalar mesons to study the internal structure of $\eta$ and ${\eta }^{\prime }$ mesons. This model facilitates the construction of the Bethe-Salpeter wavefunction, whose projection onto an appropriate flavor-basis leads to the light-front wavefunction for convenient linear combinations of the $s\bar{s}$ and $l\bar{l}\sim (u\bar{u}+d\bar{d})$ states. Using an overlap representation, we compute the valence-quark generalized parton distributions (GPDs). The construction of the model ensures that this multidimensional quantity is determined entirely by the corresponding valence-quark distribution amplitudes. Once the GPDs are constructed, we carry out a straightforward derivation of other desired physical observables such as the distribution functions and the electromagnetic form factors. We also provide explicit comparisons with available results, demonstrating that the present model offers a consistent physical picture for all ground-state pseudoscalar mesons.

   hep-phnucl-thPRD(2026)·2 citations
10. 10*

    Three-loop helicity amplitudes of four-lepton scattering in QED

    Giulio Crisanti🇬🇧 · Thomas Dave🇬🇧 · Pierpaolo Mastrolia🇮🇹 · Jonathan Ronca🇮🇹 · Sid Smith🇮🇹 · William J. Torres Bobadilla🇬🇧

    We present the analytic expressions of the three-loop virtual corrections to the helicity amplitudes of 2 -> 2 four-fermion scattering processes in massless QED. The contributing Feynman diagrams are grouped into integrand families characterised by independent Symanzik polynomials and decomposed in terms of master integrals using an optimised integration-by-parts strategy. Upon the renormalisation of the ultraviolet divergences and the extraction of the universal infrared pole structure, the finite results are expressed in terms of generalised polylogarithms up to transcendental weight six. Amplitudes for dimuon production in electron-positron annihilations, electron-muon scattering, and Bhabha scattering are explicitly derived.

    hep-phhep-thPLB(2026)·0 citations
11. 11*

    The formation of inhomogeneities in gravitational string like mode

    G.A. Kozlov🇷🇺

    The investigation of the inhomogeneities in modern inflationary Universe scenarios is related, in particular, with the study of the role played by scalar fields in cosmological evolution. We present the model described by one of the extensions of the Abelian-Higgs theory, where the scale-invariant approach to the Standard Model (SM) is achieved by introducing the complex scalar fields and the vector fields in the hidden (dark) sector, where the latter and the SM are minimally coupled to gravity. The formation of the cosmological compact objects intuitively is explained in terms of the topological line defects - the string like tubes. The strings can get an energetically preferable configuration corresponding to the magnetic flux quantum inside an area defined by the mass of dark vector field.

    hep-ph0 citations
12. 12*

    Weak Annihilation Contribution to Angular Observables in $B_c^{+}\to D^{\ast +}{\ell }^{+}{\ell }^{-}$ Decays

    Zohaib Aarfi🇵🇰 · Qazi Maaz Us Salam🇵🇰 · Ishtiaq Ahmed🇵🇰 · Faisal Munir Bhutta🇵🇰 · M.Ali Paracha🇵🇰

    We analyze the rare semileptonic decays $B_c^{+}\to D^{\ast +}(\to P_1{P}_2){\ell }^{+}{\ell }^{-}$, with $P_1{P}_2=D^{+}{\pi }^0$ or $D^0{\pi }^{+}$, and $\ell =\mu ,\tau$. We focus on the impact of weak annihilation contributions alongside penguin, box, and long-distance effects. Using the effective Hamiltonian for $b\to d{\ell }^{+}{\ell }^{-}$ transitions and $B_c\to D^{\ast }$ form factors from covariant confined quark model inputs, we compute the differential branching ratios, forward-backward asymmetry, longitudinal helicity fraction of the $D^{\ast }$, and various normalized angular coefficients. The results of the observables show that weak annihilation effects are sizable, particularly at low $q^2$, significantly modifying several observables and shifting zero-crossings. Resonance effects dominate at high $q^2$, restricting reliable analysis windows. We conclude that the inclusion of weak annihilation is essential for precise Standard Model predictions and for isolating possible New Physics effects in $B_c^{+}\to D^{\ast +}{\ell }^{+}{\ell }^{-}$ decays.

    hep-phEPJC(2026)·2 citations
13. 13*

    Three-loop QCD+QED corrections to on-shell quark renormalization

    Long Chen🇨🇳 · Hong-Yang Han🇨🇳 · Zhe Li🇨🇳 · Marco Niggetiedt🇨🇭

    We present the three-loop QCD+QED mixed corrections to the on-shell quark mass and wave-function renormalization constants through orders $\mathcal{O}({\alpha }_s^m{\alpha }^n)$ with $m+n=3$. We further derive the three-loop relation between the pole mass and the $\overline{\text{MS}}$ mass of a heavy quark, including the complete mixed QCD+QED contributions. The corresponding quark-mass anomalous dimension in the presence of both interactions is also extracted. Moreover, we provide the explicit conversion formulae, up to the same perturbative order, between the pole mass and the trace-anomaly subtracted $\sigma$-mass of heavy quark.

    hep-ph0 citations
14. 14*

    Sterile neutrino dark matter in conformal Majoron models

    João Gonçalves🇵🇹 · Danny Marfatia🇺🇸 · António P. Morais🇵🇹 · Vinícius Oliveira🇵🇹 · Roman Pasechnik🇸🇪

    We study sterile neutrino dark matter (DM) in a classically conformal U(1)' extension of the Standard Model with three right-handed neutrinos and a Majoron-like singlet scalar that generate the observed pattern of active neutrino masses and mixing via the type-I seesaw mechanism. Working in the regime of strongly suppressed active-sterile mixing, we show that the observed DM abundance can be produced through freeze-in from feeble interactions mediated by the heavy Z' and the conformal scalar. We solve the Boltzmann equation for the nonthermal phase-space distribution and confront the scenario with Lyman-$\alpha$ data by computing the matter power spectrum. For keV-scale sterile neutrinos we identify the viable parameter space consistent with structure-formation and X-ray bounds, including regions compatible with a tentative 3.5 keV line. If a second sterile state is long-lived, late decays can realize a two-component setup that alleviates the $S_8$ tension. In a highly fine-tuned variant of the model, the 220 PeV KM3NeT event can also be explained by invoking the decay of a superheavy sterile neutrino.

    hep-phastro-ph.COhep-ex1 citation
15. 15*

    Light to Heavy, Brief to Eternal: An Axion for Every Occasion (in the Early Universe)

    Francesco D'Eramo🇮🇹

    The early universe grants access to energy scales far beyond those achievable in terrestrial experiments and allows unstable Standard Model particles to play an active dynamical role. In this contribution, we focus on recent studies aimed at quantifying the potential of the early universe to probe the properties and interactions of axions. The discussion is organized around four classes of axion scenarios, ordered from long to short lifetimes: (i) stable or long-lived axions contributing to dark radiation; (ii) stable or long-lived axions produced out-of-equilibrium and constituting dark matter; (iii) metastable axions whose decays inject energy into the primordial plasma and leave observable signatures in the global 21 cm signal; and (iv) very short-lived axions that act only as portals to additional degrees of freedom. Together, these scenarios highlight the interplay between axion phenomenology and early universe cosmology and demonstrate the potential of cosmological data to probe axions over a broad range of masses and lifetimes.

    hep-phastro-ph.COPoS(2026)·0 citations
16. 16*

    Improved results of chiral limit study with the large $N_c$ standard U(3) ChPT inputs in the on-shell renormalized quark-meson model

    Vivek Kumar Tiwari🇮🇳

    When the $f_{\pi },f_K\text{ and }{M}_{\eta }^2$ given by the $(m_{\pi },m_K)$ dependent scaling relations of the large $N_c$ standard U(3) Chiral perturbation theory (ChPT) and the infrared regularized U(3) ChPT,~are used in the on-shell renormalized 2+1 flavor quark-meson (RQM) model to find its parameters in the path to the chiral limit $(m_{\pi },m_K)\to 0$ away from the physical point $(m_{\pi }^{\text{Phys}},m_K^{\text{Phys}})=(138,496)$ MeV,~one gets the respective framework of RQM-S model and RQM-I model.~Computing and comprehensively comparing the RQM-S and I model Columbia plots for the $m_{\sigma }=400,500\text{ and }600$ MeV,~it has been shown that the use of large $N_c$ standard U(3) ChPT inputs give the better and improved framework for the Chiral limit studies as the RQM-S model tricritical lines show the expected saturation pattern after becoming flat in the vertical meson (quark) mass $\mu -m_K$ ($\mu -m_s$) plane for all the cases of $m_{\sigma }$ whereas the divergent RQM-I model tricritical line for the $m_{\sigma }=500$ MeV becomes strongly divergent when the $m_{\sigma }=600$ MeV.

    hep-ph0 citations
17. 17*

    Pion $\beta$ decay and $\tau \to \pi \pi {\nu }_{\tau }$ beyond leading logarithms

    Vincenzo Cirigliano🇺🇸 · Martin Hoferichter🇨🇭 · Nicola Valori🇪🇸

    The consistent matching of short-distance contributions and hadronic matrix elements is crucial for precise predictions of weak processes involving hadrons. In this Letter, we address this point for charged-current processes involving two pions -- pion $\beta$ decay ${\pi }^{\pm }\to {\pi }^0{e}^{\pm }{\nu }_e$ and hadronic $\tau$ decays ${\tau }^{\pm }\to {\pi }^{\pm }{\pi }^0{\nu }_{\tau }$ -- whose decay rates depend on the so-called $\gamma W$ box correction. Using recent results from lattice QCD, we show how to formulate the matching beyond leading-logarithmic accuracy, in particular, how to cancel the dependence on the scheme choice for evanescent operators. As main results, we obtain a prediction for the decay rate of pion $\beta$ decay with theory uncertainties improved by a factor of three, which renders theory uncertainties negligible for future determinations of $V_{ud}$ even beyond the reach of the PIONEER experiment, and an evaluation of isospin-breaking corrections to $\tau \to \pi \pi {\nu }_{\tau }$ with negligible uncertainty from the short-distance matching, as necessary for a future $\tau$-based determination of the hadronic-vacuum-polarization contribution to the anomalous magnetic moment of the muon.

    hep-phhep-exhep-latnucl-ex+1PRL(2026)·10 citations
18. 18*

    The X17 with Chiral Couplings

    Max H. Fieg🇺🇸 · Toni Mäkelä🇺🇸 · Tim M.P. Tait🇺🇸 · Miša Toman🇺🇸

    In recent years, the ATOMKI collaboration has performed a series of measurements of excited nuclei, observing a resonant excess of electron-positron pairs at large opening angles compared to the Standard Model prediction. The excess has been hypothesized to be due to the production of a new spin-1 or spin-0 particle, X17, with a mass of about 17 MeV. Recently, the PADME experiment has reported an excess in the $e^{+}{e}^{-}$ cross section at center-of-mass energies near 17 MeV, perhaps further hinting at the existence of a new state. Studies of the spin-1 case have hitherto focused on either vector {\em or} axial-vector couplings to quarks and leptons, whereas UV theories more naturally produce {\em both} vector and axial-vector (\textit{i.e.} chiral) couplings, analogous to the Standard Model weak interactions. We consider the ATOMKI anomalies in the context of an $X$ with chiral couplings to quarks and explore the parameter space that can explain the ATOMKI anomalies, contrasting them with experimental constraints. We find that it is possible to accommodate the reported ATOMKI signals. However, the $99\%$ CL region is in tension with null results from searches for atomic parity violation and direct searches for new low mass physics coupled to electrons. This tension is found to be driven by the magnitude of the reported excess in the transition of ${}^{12}\mathrm{C}(17.23)$, which drives the best-fit region towards excluded couplings.

    hep-phPRD(2026)·6 citations
19. 19*

    Thermal precondensation in gauge-fermion theories

    Álvaro Pastor-Gutiérrez🇯🇵 · Jan M. Pawlowski🇩🇪 · Franz R. Sattler🇩🇪

    Precondensation is a peculiar phenomenon in phase transitions, characterised by the occurrence of a condensate only over a finite range of length scales. It is closely connected to the emergence of domains, pseudo-gapped phases and spatial inhomogeneities in equilibrium. In this work, we show its occurrence in gauge-fermion theories in the chiral limit, close to the thermal chiral phase transition. We further show that the precondensation regime becomes increasingly pronounced and extends over a wider temperature range as the number of fermion flavours is increased. We analyse the underlying dynamics which is shared by a broad class of fermionic systems, ranging from condensed matter to high-energy physics. Specifically, we discuss the potential relevance of this phenomenon for physics beyond the Standard Model.

    hep-phcond-mat.stat-mechcond-mat.str-elhep-lat+12 citations
20. 20*

    Fate of ${\theta }_{12}$ under $\mu -\tau$ Reflection Symmetry in Light of the First JUNO Results

    Ranjeet Kumar🇰🇷

    The recent Jiangmen Underground Neutrino Observatory (JUNO) measurements of ${\theta }_{12}$ and $\Delta m_{21}^2$ open a new avenue for probing flavor symmetric structures in the lepton sector. Motivated by this, we study a model in which $\mu -\tau$ reflection symmetry naturally emerges from an underlying $A_4$ flavor symmetry within a type-II seesaw framework. Beyond its standard predictions of ${\theta }_{23}=45^{\circ }$ and ${\delta }_{\mathrm{CP}}=\pm \pi /2$, the framework yields testable predictions for ${\theta }_{12}$ that can be probed by JUNO. Two viable scenarios arise, one predicting ${\sin }^2{\theta }_{12}\text{gsim}0.335$, which is strongly disfavored by the latest JUNO results. Correlations between ${\theta }_{12}$ and model parameters further enhance the model's predictivity. Future measurements at DUNE and T2HK will provide complementary tests of this scenario.

    hep-phPRD(2026)·2 citations
21. 21*

    Accelerated expansion of the universe purely driven by scalar field fluctuations

    Daniel Jiménez-Aguilar🇺🇸

    We show that scalar field fluctuations alone can drive cosmic acceleration, provided the universe is spatially closed and the Compton wavelength of the field exceeds the radius of curvature. This mechanism may open new perspectives on inflation and dark energy, which could arise from a gas of sufficiently light bosons in a closed universe.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2026)·0 citations
22. 22*

    Cosmological production of dark matter in the Universe and in the laboratory

    Álvaro Parra-López🇪🇸

    This thesis investigates cosmological particle production within Quantum Field Theory in Curved Spacetimes, both as a dark matter mechanism and through analog simulations using Bose-Einstein condensates. While a full theory of Quantum Gravity remains elusive, studying quantum fields on curved backgrounds provides essential insights into the early Universe. We focus on how dynamical spacetimes, particularly during inflation, generate particles from spectator fields influenced solely by geometry. The work is divided into four parts. Part I establishes the theoretical framework, covering cosmology, inflation, and the principles of analog gravity. Part II analyzes particle production in various inflationary models, showing that scalar and vector fields can account for observed dark matter abundance, especially through tachyonic instabilities. Part III explores BEC experiments, mapping phonons to scalar fields in expanding universes. We demonstrate the reconstruction of expansion histories, reinterpret production as a scattering problem, and propose methods to measure entanglement between produced pairs. Finally, Part IV addresses quantum vacuum ambiguities and the impact of non-adiabatic transitions during the "switch-on" and "switch-off" of expansion. Ultimately, this work highlights the viability of cosmological particle production for dark matter and the power of analog experiments to enhance our understanding of quantum effects in curved spacetimes.

    ↳ gr-qccond-mat.quant-gashep-phhep-th0 citations
23. 23*

    An improved linear Boltzmann transport model for hadron and jet suppression in ultrarelativistic heavy-ion collisions

    Yichao Dang🇨🇳 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳

    Jets serve as powerful tomographic probes of the quark-gluon plasma (QGP) created in relativistic heavy-ion collisions. While the expanding landscape of jet observables reveals multi-faceted aspects of jet-medium interactions, a precise and simultaneous description of the nuclear modification factors of hadrons and full jets remains a challenge for theoretical models. In this work, we present two essential improvements to the linear Boltzmann transport (LBT) model to bridge this gap. First, instead of implementing in-medium parton transport after vacuum parton showers complete, we introduce a medium scale at which in-medium parton transport is inserted into the vacuum parton showers, providing a more physical picture of parton-QGP interactions. Second, we incorporate color flow information into the LBT model, enabling string connections between partons whose configurations are correlated with the medium-modified parton showers before hadronization. We demonstrate that both improvements alter the predicted ratio of hadron to jet quenching, leading to a satisfactory unified description of the nuclear modification factors of hadrons and jets with different flavors.

    ↳ nucl-thhep-phnucl-exNucl.Sci.Tech.(2026)·6 citations
24. 24*

    Improving integration-by-parts and differential equations

    Iris Bree🇩🇪 · Federico Gasparotto🇩🇪 · Antonela Matijašić🇩🇪 · Pouria Mazloumi🇩🇪 · Dmytro Melnichenko🇩🇪 · Sebastian Pögel🇨🇭 · Toni Teschke🇩🇪 · Xing Wang🇨🇳 · Stefan Weinzierl🇩🇪 · Konglong Wu🇨🇳 · Xiaofeng Xu🇨🇳

    In this talk, we discuss how ideas from geometry help to improve Feynman integral reduction and the construction of $\epsilon$-factorised differential equations. In particular, we outline a systematic procedure to obtain an $\epsilon$-factorised differential equation for any Feynman integral.

    ↳ hep-thhep-ph2 citations
25. 25*

    Classical strings and the double copy

    Riccardo Morieri🇮🇹 · Igor Pesando🇮🇹 · Michael L. Reichenberg Ashby🇬🇧 · Chris D. White🇬🇧

    The double copy is by now a well-established relationship between scattering amplitudes and classical solutions in gauge and gravity (field) theories, and is itself inspired by amplitude relations in string theory. In this paper, we generalise the classical double copy to the motion of strings, taking as a case study the motion of an open string in a background abelian gauge field. We argue that the double copy of this situation is a closed string moving in a spacetime background arising as the double copy of the gauge theory background. The gauge theory background we consider is that of a constant electric field, which has a critical value beyond which the open string motion is pathological. We find no counterpart of this behaviour in the double copy, and interpret this result. We then examine how the closed string nevertheless still knows about the single copy gauge theory. Our results pave the way for more systematic study of the double copy in a classical string context, thus going beyond the KLT relations for amplitudes in flat space.

    ↳ hep-thgr-qchep-phJHEP(2026)·2 citations
26. 26*

    Dirac mode localization in QCD near the crossover temperature

    Matteo Giordano🇭🇺 · Tamas G. Kovacs🇭🇺 · Ferenc Pittler🇨🇾

    We study the localization properties of the low-lying Dirac eigenmodes in QCD near the crossover temperature, using stout-smeared staggered fermions and Symanzik-improved gauge action on the lattice. On $N_{\mathrm{t}}=8$ lattices we find that localized low modes, absent at low temperature, appear at a temperature $T_{\mathrm{loc}}$ in the range $150\mathrm{MeV}\le T_{\mathrm{loc}}\le 160\mathrm{MeV}$, well within the chiral crossover range as determined from the chiral condensate and from the light-quark susceptibility. Since with our choice of lattice action neither the chiral transition region nor the renormalized mobility edges change significantly above $N_{\mathrm{t}}=8$, our conclusion that $T_{\mathrm{loc}}$ is in the chiral crossover region is expected to remain valid in the continuum limit.

    ↳ hep-latcond-mat.dis-nnhep-phhep-thPRD(2026)·1 citation
27. 27*

    Strong potential in a box for applications to femtoscopy

    Gleb Romanenko🇮🇹 · Francesca Bellini🇮🇹

    Understanding the short-range nucleon-nucleon interaction is essential for the interpretation of correlation femtoscopy measurements in high-energy hadronic and nuclear collisions. We present an analytical treatment of the strong interaction in two-nucleon systems by modelling it with a square-well potential and solving the Schroedinger equation in the presence of the Coulomb interaction. The resulting pair wave function is regular at small relative distances and allows for the inclusion of multiple partial waves. We apply this framework to proton-proton femtoscopy and compute theoretical correlation functions for realistic source sizes. We demonstrate that the commonly used Lednicky-Lyuboshits asymptotic approximation overestimates the correlation signal for small sources. Comparisons with numerical calculations using the CATS framework and the Argonne v18 potential show good agreement within current experimental uncertainties. The proposed analytical approach provides a practical and flexible tool for femtoscopic analyses of nucleon and baryon pairs.

    ↳ nucl-thhep-phnucl-ex2 citations
28. 28*

    Beyond thermal approximations: Precise cosmological bounds on Axion-Like Particles

    Nicola Barbieri🇪🇸 · Luca Caloni🇪🇸 · Martina Gerbino🇮🇹 · Massimiliano Lattanzi🇮🇹 · Luca Visinelli🇮🇹

    We derive updated cosmological bounds on light axion-like particles (ALPs) coupled to leptons or photons, using a full phase-space treatment of their production from the primordial thermal plasma. The ALP phase-space distribution, obtained by solving the momentum-dependent Boltzmann equation for the relevant production processes, is consistently propagated into the computation of cosmological observables, allowing us to assess the impact of non-thermal spectral distortions on the effective number of relativistic species, $\Delta N_{\mathrm{eff}}$. Using state-of-the-art measurements of the cosmic microwave background from Planck, the Atacama Cosmology Telescope, and the South Pole Telescope, complemented with Big Bang Nucleosynthesis determinations of primordial deuterium and helium abundances, we obtain the following 95\% credible limits on the ALP decay constant: $f_a>1.63\times 10^6\mathrm{GeV}$, $9.41\times 10^6\mathrm{GeV}$ and $8.06\times 10^4\mathrm{GeV}$ for ALPs coupled to electrons, muons and taus, respectively. For the ALP-photon coupling we find $g_{a\gamma }<1.98\times 10^{-8}{\mathrm{GeV}}^{-1}$. Including baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument mildly relaxes the constraints, in line with previous analyses of extra relativistic degrees of freedom. Finally, we present forecasts for the LiteBIRD$+$Simons Observatory and LiteBIRD$+$CMB-HD configurations, discussing the importance of an exact phase-space treatment for robust cosmological bounds on ALP interactions.

    ↳ astro-ph.COhep-phJCAP(2026)·8 citations
29. 29*

    Rotation catalyzed chiral magnetovortical instability

    Shuai Wang🇨🇳 · Xu-Guang Huang🇨🇳

    We demonstrate that a background rotation significantly catalyzes the chiral magnetovortical instability in chiral magnetohydrodynamics. The rotation splits the linearly polarized Alfven wave into two circularly polarized magneto-Coriolis waves, one of which exhibits a lower frequency than the original Alfven wave. We find that this low-frequency magneto-Coriolis wave is always unstable in the presence of even a weak chiral vortical effect. This instability may enable new dynamo mechanism applicable to various rotating chiral plasmas.

    ↳ nucl-thastro-ph.HEhep-phphysics.plasm-phPRD(2026)·2 citations
30. 30*

    Nucleon Parton Distribution Functions from Boosted Correlations in the Coulomb gauge

    Xiang Gao🇺🇸 · Jinchen He🇺🇸 · Joshua Lin🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Rui Zhang🇺🇸 · Yong Zhao🇺🇸

    Recently, a novel approach has been proposed to compute parton distributions through the use of boosted correlators fixed in the Coulomb gauge from lattice QCD, within the framework of Large-Momentum Effective Theory (LaMET). This approach circumvents the need for Wilson lines, potentially enhancing the efficiency and accuracy of lattice calculations. In this work, we present the first exploratory implementation of the Coulomb gauge method for calculating nucleon unpolarized, helicity, and transversity parton distribution functions (PDFs). The calculations are performed on a Highly-Improved-Staggered-Quark ensemble with lattice spacing $a=0.06$ fm, volume $L_s^3\times L_t=48^3\times 64$, and valence pion mass $m_{\pi }=300$ MeV, employing boosted nucleon states with momenta up to 3.04 GeV. Our lattice predictions for the valence-quark PDFs -- extracted from the real part of the correlators -- show good convergence with increasing nucleon momentum and are compatible with the most recent global analyses for all spin structures. On the other hand, the full-quark-channel PDFs obtained from the imaginary part of the correlators exhibit discrepancies between the two large nucleon momenta considered, although the results at the higher momentum are consistent with phenomenology. The discrepancies are likely driven by stronger excited-state contamination in the imaginary matrix elements, which is consistent with the observation in the literature. Overall, this work demonstrates the efficacy of the Coulomb gauge approach for nucleon PDFs and serves as a benchmark for its broader applications.

    ↳ hep-lathep-exhep-phnucl-ex+19 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.