Thu·Jul 31, 2025Thursday·July 31, 2025

1. 01*

   Bayesian inference and jet quenching

   Raymond Ehlers🇺🇸

   These proceedings review the application of Bayesian inference to high momentum transfer probes of the quark--gluon plasma (QGP). Bayesian inference techniques are introduced, highlighting critical components to consider when comparing analyses. Recent calibrations using hadron observables are described, illustrating the importance of the choice of parametrization. Additional recent analyses that characterize the impact of the inclusion of jet observables, as well as soft-hard correlations, are reviewed. Finally, lessons learned from these analyses and important questions for the future are highlighted.

   hep-phnucl-exnucl-thEPJ Web Conf.(2025)·0 citations
2. 02*

   Compositeness of near-threshold states with repulsive Coulomb interaction combined with short-range potential

   Tomona Kinugawa🇯🇵 · Tetsuo Hyodo🇯🇵

   We investigate the internal structure of near-threshold states in a system with a repulsive Coulomb interaction combined with a short-range potential, using the compositeness. We construct a model in which the eigenmomentum is expressed in terms of three observables: the Coulomb scattering length, the Coulomb effective range, and the Bohr radius. In the presence of the Coulomb interaction, a bound state directly goes into a resonance as parameters are varied, bypassing a virtual state, in contrast to the case with only the short-range interaction. We show that the compositeness of near-threshold states can be expressed solely in terms of these observables. When the magnitude of the Coulomb effective range is much smaller than that of the Bohr radius, both shallow bound states and near-threshold resonances exhibit common structures with large compositeness, reflecting the remnant of the low-energy universality.

   hep-phnucl-thPoS(2026)·2 citations
3. 03*

   Role of meson exchange and final-state interaction in $J/\psi$-meson photoproduction

   Sang-Ho Kim🇰🇷

   We investigate $J/\psi$ photoproduction off the nucleon using a dynamical model based on a Hamiltonian framework. First, Pomeron exchange is regarded as a background contribution that accounts for the gradual rise of the total cross section with increasing beam energy. Then, the meson-exchange and direct $J/\psi$-radiation contributions are included as part of the Born term. More specifically, we examine the contributions of the light-meson [${\pi }^0(135)$, $\eta (548)$, ${\eta }^{\prime }(958)$, $f_1(1285)$] and charmonium-meson [${\eta }_c(1S)$, ${\chi }_{c0}(1P)$, ${\chi }_{c1}(1P)$, ${\eta }_c(2S)$, ${\chi }_{c1}(3872)$] exchanges in the $t$-channel diagram. Most of the coupling constants are determined from the radiative decays of the $J/\psi$ or other relevant charmonium states. Finally, we consider the $J/\psi N$ final-state interaction (FSI) within the leading-order approximation, which includes gluon-exchange and direct $J/\psi N$-coupling terms. The model parameters of the Hamiltonian are fitted to the data from the GlueX and $J/\psi$-007 experiments at Jefferson Laboratory (JLab). The light mesons $\eta (548)$ and ${\eta }^{\prime }(958)$ are found to make the most significant contributions, whereas the charmonium mesons play only a minor role. The direct $J/\psi$-radiation term begins to come into play only in the backward scattering regions. The FSI contribution is suppressed by a factor of $10^1-10^2$ in comparison to the Born-term contribution when a Yukawa-type potential is employed for the charmonium-nucleon interaction. Our results agree well with the available JLab data on the total and $t$-dependent differential cross sections. High-precision, angle-dependent data in the threshold region ($E_{\gamma }⩽8.9$ GeV) are crucial for confirming the FSI effect.

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

   Chiral symmetry and its breaking

   Alexey Nefediev🇩🇪

   In addition to fundamental symmetries playing a crucial role for establishing the Standard Model of fundamental interactions, approximate symmetries provide essential insight into the respective phenomena and shed light on the underlying physics. Here we give a brief pedagogical introduction to chiral symmetry as an approximate but still rather accurate symmetry of strong interactions and its spontaneous breaking in the vacuum of Quantum Chromodynamics. Special attention is paid to a microscopic picture of this phenomenon and understanding a dual nature of the chiral pion that is the Goldstone boson related to spontaneous breaking of chiral symmetry and the lowest pseudoscalar quark-antiquark state in the spectrum of hadrons simultaneously.

   hep-phEncyclopedia of Particle Physics, vol 1, …·3 citations
5. 05*

   On the contribution from the light quarks to $H\to \gamma \gamma ,\gamma Z$

   Marc Knecht🇫🇷 · Baiyi Qian🇫🇷

   This Letter addresses the contribution from the light $u,d,s$ quarks to the amplitudes for the decay modes of the Brout-Englert-Higgs scalar boson $H$ into two photons ($H\to \gamma \gamma$) or to a photon and a neutral weak gauge boson ($H\to \gamma Z$), taking into account the non-perturbative aspects of QCD. Contrary to a recent claim, the contribution from the light quarks does not vanish. Rather, it is shown that, in contrast to the perturbative evaluations usually considered in the literature, this contribution to the amplitudes starts with a term that is linear, and not quadratic, in the masses of the light quarks, thus pointing toward a sizeable enhancement of their contribution to $H\to \gamma \gamma$.

   hep-phPLB(2026)·2 citations
6. 06*

   Higgs production via vector-boson fusion at the LHC

   Gaetano Barone🇺🇸 · Jiayi Chen🇨🇦 · Stephane Cooperstein🇺🇸 · Nikita Dolganov🇨🇦 · Silvia Ferrario Ravasio🇨🇭 · Yacine Haddad🇺🇸 · Stefan Höche🇺🇸 · Barbara Jäger🇩🇪 · Alexander Karlberg🇨🇭 · Alexander Mück🇩🇪 · Mathieu Pellen🇩🇪 · Christian T. Preuss🇩🇪 and 3 other authors

   In this article, we summarise the recent experimental measurements and theoretical work on Higgs boson production via vector-boson fusion at the LHC. Along with this, we provide state-of-the-art predictions at fixed order as well as with parton-shower corrections within the Standard Model at 13.6 TeV. The results are presented in the form of multi-differential distributions as well as in the Simplified Template Cross Section bins. All materials and outputs of this study are available on public repositories. Finally, following findings in the literature, recommendations are made to estimate theoretical uncertainties related to parton-shower corrections.

   hep-phhep-exSciPost Phys.Comm.Rep.(2025)·6 citations
7. 07*

   Kaon-deuteron femtoscopy from unitarized chiral interactions

   Àngels Ramos🇪🇸 · Juan M. Torres-Rincon🇪🇸 · Alejandro de Fagoaga🇪🇸 · Esteve Cabré🇪🇸

   We have performed a theoretical study of the correlation functions of $K^{-}d$ and $K^{+}d$ pairs and compared them with those provided by the ALICE Collaboration from Pb-Pb collisions, and also from high-multiplicity p-p collisions in the case of $K^{+}d$. In addition to implementing the effect of the Coulomb force, the $K^{-}d$ and $K^{+}d$ wave functions are derived from the corresponding strong scattering amplitudes that are built employing a unitarized chiral model for the elementary $K^{-}N$ and $K^{+}N$ interactions. We present results for the impulse approximation, which accounts for single-scattering processes of the kaon with the nucleons of the deuteron, as well as for the solution of the Faddeev equations in the so-called fixed center approximation, which includes multiple rescattering effects. The $K^{-}d$ correlation function is shown to be very sensitive to both the size of the source and the relative momentum of the interacting pair, with large deviations from the Coulomb baseline and sizable multi-step scattering contributions, effects that are tied to a $\bar{K}N$ strong interaction that is dominated by the influence of the subthreshold resonance $\Lambda (1405)$. In contrast, the $K^{+}d$ correlation function only differs appreciably from the Coulomb one for relatively small sources, reflecting the mildly repulsive and elastic behavior of the $KN$ strong force. The calculated correlation functions are found to nicely reproduce the experimental data of the ALICE collaboration. Our study serves to reinforce the validity of the theoretical models employed and demonstrates the value of femtoscopy as a powerful tool for probing hadronic interactions involving strangeness.

   hep-phnucl-exnucl-thPRD(2026)·8 citations
8. 08*

   All-gluon amplitudes with off-shell recursion in multiplet bases

   Oskar Bolinder🇸🇪 · Rikkert Frederix🇸🇪 · Malin Sjodahl🇸🇪

   The efficient computation of color-summed QCD amplitudes at high parton multiplicities remains a central challenge for precision collider predictions. Existing approaches using trace, color-flow, or adjoint bases suffer from non-orthogonality, which complicates the color algebra and scales poorly with multiplicity. In this work, we present an off-shell recursive framework for computing all-gluon tree-level amplitudes directly in orthogonal multiplet bases. Utilizing Wigner $6j$ coefficients, we construct an algorithm that builds multiplet-projected off-shell currents from lower-point currents. By optimizing the recursion through partial summation and caching, we find that the computational complexity of calculating $n$-gluon color-summed squared amplitudes scales as $\mathcal{O}(17^n)$. This demonstrates the potential competitiveness of multiplet bases for high-multiplicity processes.

   hep-phJHEP(2025)·3 citations
9. 09*

   Distorted quarkonia and spin alignment

   Guowei Yan🇨🇳 · Shu Lin🇨🇳

   It is well-known that atoms can change their shape when subject to external electromagnetic fields. Analogous phenomenon is expected for particles, which are much smaller in size with the corresponding shape change much harder to observe. We point out that shape change of particles can be accessed by measurements of their spin alignment. Motivated by recent measurements of spin alignment in relativistic heavy ion collisions, we consider quarkonia in electromagnetic fields as an example. We show that the quarkonia spin alignment receives both spin contribution from spin states mixing and orbital contribution from shape change. By a proper choice of quantization axis, it is possible to switch off the spin contribution, leaving only the orbital contribution. This makes spin alignment measurement a valuable probe of quarkonium structure.

   hep-phnucl-exnucl-thPRD(2026)·3 citations
10. 10*

    Entanglement suppression and emergent symmetries in hadron scatterings

    Tao-Ran Hu🇨🇳 · Su Chen🇨🇳 · Katsuyoshi Sone🇯🇵 · Feng-Kun Guo🇨🇳 · Tetsuo Hyodo🇯🇵 · Ian Low🇺🇸

    Recently entanglement suppression was proposed to be one potential origin of emergent symmetries. In this work, we extend this theoretical framework to accommodate particles with arbitrary spins and/or arbitrary group representations. As case studies, we discuss recent efforts to test the entanglement-suppression conjecture in two hadron systems that exhibit possible emergent symmetries. The first concerns interactions involving spin-3/2 baryons, where entanglement suppression gives rise to symmetries such as $\text{SU}(40)$ spin-flavor symmetry. The second system involves low-energy scattering of heavy mesons, where entanglement suppression leads to an enhancement of the inherent heavy-quark spin symmetry to a light-quark spin symmetry, predicting additional siblings for the prominent exotic double-charm meson $T_{cc}(3875{)}^{+}$. These predictions should be confronted against experimental data and lattice results to further test the minimal-entanglement conjecture.

    hep-phhep-thnucl-thquant-phPoS(2026)·8 citations
11. 11*

    Scaling functions in the soft-wall AdS/QCD models

    Zhongzheng Zhang🇨🇳 · Danning Li🇨🇳 · Lang Yu🇨🇳 · Zhibin Li🇨🇳 · Xinyang Wang🇨🇳

    We investigate the static scaling behavior of the chiral condensate near the two-flavor critical point within the framework of the soft-wall AdS/QCD. The scaling functions are extracted from the chiral order parameters and are found to precisely match those obtained through mean-field calculations. Additionally, it is also checked that the scaling functions are independent of the specific construction of the holographic model. Furthermore, we develop the formalism for calculating the chiral susceptibility and demonstrate that the pseudo-critical temperatures obey the scaling law for moderate quark masses. It is shown that the temperature scaling could be comparable with those obtained from Dyson-Schwinger equations and lattice simulations. These findings could help improve the effectiveness of the soft-wall AdS/QCD.

    hep-phPRD(2026)·2 citations
12. 12*

    Pseudoscalar meson dominance, the pion-nucleon coupling constant and the Goldberger-Treiman discrepancy

    Enrique Ruiz Arriola🇪🇸 · Pablo Sanchez-Puertas🇪🇸

    We analyze the matrix elements of the pseudoscalar density with pion-quantum numbers $I^G{J}^{PC}=1^{-}{0}^{-+}$ in the nucleon in terms of dispersion relations, PCAC and pQCD asymptotic sum rules for the pseudoscalar form factor. We show that the corresponding spectral density must have at least one zero. A model based on ChPT at low energies, resonances at intermediate energies, Regge power-like behaviour at high energies and pQCD at asymptotically high energies, allows to deduce the pion-nucleon coupling constant and the Goldberger-Treiman discrepancy ${\Delta }_{\mathrm{GT}}=1-\frac{m_N{g}_A}{F_{\pi }{g}_{\pi NN}}$, yielding the results for the charged channel \[g_{\pi^+ pn} = 13.14(^{+6}_{-4})(7)_{\rm IB}, \quad \Delta_{\rm GT} = 1.26(^{+51}_{-34})(50)_{\rm IB}\ , \] to be compared with the most precise determinations, $g_{{\pi }^{+}np}=13.25(5)$ (and hence ${\Delta }_{\mathrm{GT}}=2.1(4)\%$), from $np,pp$ scattering analysis of the Granada-2013 database and $g_{{\pi }^{+}pn}=13.11(10)$, ${\Delta }_{\mathrm{GT}}=1.0(7)\%$ from the GMO sum rule. Our work supports the concept of pseudoscalar dominance in the nucleon structure suggested by Dominguez long ago. The minimal resonance saturation of the pseudoscalar form factor of the nucleon with the lowest isovector-pseudoscalar mesons compatible with analyticity, pQCD short distance constraints and chiral symmetry leads to an extended PCAC in the large-$N_c$ limit, and effectively depends on the $\pi (1300)$ excited pion state. Our results are compatible, though more accurate, than recent lattice QCD studies and are consistent with almost flat strong pion-nucleon-nucleon vertices.

    hep-phhep-latEur.Phys.J.ST(2026)·5 citations
13. 13*

    Pionic gluons from global QCD analysis of experimental and lattice data

    William Good🇺🇸 · Patrick C. Barry🇺🇸 · Huey-Wen Lin🇺🇸 · W. Melnitchouk🇺🇸 · Alex NieMiera🇺🇸 · Nobuo Sato🇺🇸

    We perform the first global QCD analysis of parton distribution functions (PDFs) in the pion, with lattice-QCD data on gluonic pseudo--Ioffe-time distributions fitted simultaneously with experimental Drell-Yan and leading neutron electroproduction data. Inclusion of the lattice results with parametrized systematic corrections significantly reduces the uncertainties on the gluon PDF at parton momentum fractions $x\gtrsim 0.2$, revealing a higher gluon density in the pion at large $x$ than in the proton. The similar gluon momentum fractions in the pion and proton further suggests a relative suppression of the pion gluon density at small $x$.

    hep-phhep-exhep-latnucl-th7 citations
14. 14*

    Review of the Higgs boson production via vector boson fusion and its decay into bottom quarks in $pp$ collisions at $\sqrt{s}=8,13$ TeV

    Fikriye C I Kaya · Ibrahim Mirza🇺🇸

    We present a comprehensive overview of the vector boson fusion production and the following decay of the Higgs boson to two bottom quarks (\(H\!\to\! b\bar{b}\)), which dominates the Higgs total width yet remains experimentally challenging because of substantial QCD multijet backgrounds. We overview the use of boosted decision trees, which advance jet reconstruction and flavour tagging by including boosted topologies and deep-learning-based \(b\)-tagging and which improve sensitivity in associated production channels. Special attention is given to ATLAS and CMS selections and results pertaining to the vector boson fusion production of Higgs, decaying in the $b\bar{b}$-channel, from both the 8 TeV and the 13 TeV LHC data-sets conducted with up to 90.8 $f{b}^{-1}$ of Data and published through 2024. Consistent with the Standard Model gauge symmetry \(SU(3)_C \times SU(2)_L \times U(1)_Y\) predictions, we emphasise how \(H\!\to\! b\bar{b}\) measurements contribute, in conjunction with other production modes and decay channels, to tests of the bottom-quark Yukawa coupling, which is an essential probe of the electroweak symmetry-breaking mechanism. Finally, we discuss how the current precision constrains deviations in the bottom-quark Yukawa coupling, outline ongoing efforts during Run 3, and consider the prospects of forthcoming high-luminosity LHC operation and the proposed Future Circular Collider in further tightening precision tests of the Standard Model and beyond.

    hep-phhep-ex0 citations
15. 15*

    The $1/N_c$ Operator Analysis of the Combined Octet and Decuplet Baryons Contact Interactions in SU(3) Chiral Effective Field Theory

    Chindanai Bubpatate · Dominador F. Vaso · Jr. · Daris Samart

    In this work, we construct the non-derivative four-point interactions for Octet and Decuplet baryons in the SU(3) Chiral Effective Field Theory (ChEFT) framework, and there are 104 coupling constant terms. The non-relativistic expansion of the baryon fields has been considered up to the Next-to-Leading Order (NLO) of the three-momentum expansion. We find 28 and 106 Low-Energy Constants (LECs) for Leading Order (LO) and NLO, respectively. Using the Hartree Hamiltonian of the $1/N_c$ expansion of the operator product up to Next-to-Next-to-Leading Order (NNLO), we can reduce the free parameters (LECs) of the ChEFT from 134 down to 24 up to NLO of the three-momentum expansion. Moreover, we will discuss the implications of the $1/N_c$ sum rules in $\Omega \Omega$ and $\Omega N$ scatterings, where the future results from lattice QCD can be used to test our sum rules.

    hep-phnucl-thEPJC(2026)·2 citations
16. 16*

    Recoil-Safe Subtraction, Matching and Merging in e+e- to hadrons

    Stefan Höche🇺🇸 · Frank Krauss🇬🇧 · Peter Meinzinger🇨🇭 · Daniel Reichelt🇨🇭

    We present the first next-to-leading order matched and multi-jet merged predictions based on the Alaric parton shower. The components needed for infrared subtraction in the S-MC@NLO algorithm are computed analytically for the case of color singlet decays to hadronic final states and validated against existing approaches for up to e+e- to 5 jets. Phenomenological results for e+e- to hadrons at the Z pole are obtained with up to five jets at next-to-leading order precision, for the first time using an evolution algorithm with NLL-preserving kinematics mapping.

    hep-phJHEP(2026)·8 citations
17. 17*

    From Capture to Collapse: Revisiting Black Hole formation by Fermionic Asymmetric Dark Matter in Neutron Stars

    Sandra Robles🇺🇸 · Drona Vatsyayan🇪🇸 · Giorgio Busoni🇦🇺

    Fermionic asymmetric dark matter (ADM) can be captured in neutron stars (NSs) via scatterings with the star constituents. The absence of dark matter annihilation due to its asymmetric nature leads to ADM accumulation in the NS core, potentially reaching densities sufficient to exceed the Chandrasekhar limit and trigger its gravitational collapse into a black hole (BH), eventually consuming the NS from within. Therefore, the existence and observation of old neutron stars provide a means to constrain the properties of ADM. We revisit previous constraints on the mass and scattering cross section off neutrons of fermionic ADM across a class of models. We critically examine common simplifying approximations used in the literature to derive these limits. Our analysis includes improved treatments of dark matter capture, thermalization, BH formation, accretion, and evaporation. We find that previous results can be relaxed by a few orders of magnitude once these effects are properly accounted for.

    hep-phastro-ph.COastro-ph.HEPRD(2025)·8 citations
18. 18*

    Fantômas Unconfined: global QCD fits with Bézier parameterizations

    Lucas Kotz🇺🇸 · Aurore Courtoy🇲🇽 · T. J. Hobbs🇺🇸 · Pavel Nadolsky🇺🇸 · Fredrick Olness🇺🇸 · Maximiliano Ponce-Chavez🇺🇸 · Varada Purohit🇺🇸

    Fantômas is a C++ toolkit for exploring the parametrization dependence of parton distribution functions (PDFs) and other correlator functions in quantum chromodynamics (QCD). Fantômas facilitates the generation of adaptable polynomial parametrizations for PDFs, called metamorphs, to find best-fit PDF solutions and quantify the epistemic uncertainty associated with the parametrizations during their fitting. The method employs Bézier curves as universal approximators for a variety of PDF shapes. Integrated into the xFitter framework for the global QCD analysis, Fantômas provides a foundation for general models of PDFs, while reducing the computational time compared to the approaches utilizing traditional polynomial parametrizations as well as providing an interpretable alternative to neural-network-based models. This paper outlines the structure and practical usage of the Fantômas toolkit, including its inputs, outputs, and implementation within xFitter. It also provides a practical example of using Fantômas for uncertainty quantification as well as the combination of PDF fits into a single ensemble.

    hep-phComput.Phys.Commun.(2026)·8 citations
19. 19*

    Gamma-Rays and Gravitational Waves from Inelastic Higgs Portal Dark Matter

    Dan Hooper🇺🇸 · Gordan Krnjaic🇺🇸 · Duncan Rocha🇺🇸 · Subhojit Roy🇺🇸

    We explore a simple and predictive dark matter scenario involving a complex scalar field, $\varphi$, coupled to the Higgs portal with no additional field content. In the UV, the field possesses a global $U(1)$ symmetry which is broken by mass terms and Higgs portal interactions. In the mass basis, the complex field splits into a pair of real scalars with a small mass splitting (in analogy to pseudo-Dirac fermions), such that the Higgs portal acquires both diagonal and off-diagonal terms with respect to these eigenstates. In the parameter space where the off-diagonal interaction predominates, this scenario is safe from direct detection constraints. Moreover, this model provides a viable explanation for the longstanding Galactic Center gamma-ray excess. Additionally, this model influences the Higgs potential in a way that could facilitate a strong first-order electroweak phase transition in the early universe, potentially leading to a stochastic gravitational wave background that could fall within the reach of upcoming space-based detectors.

    hep-phastro-ph.COPRD(2026)·18 citations
20. 20*

    Charged Loops at the Cosmological Collider with Chemical Potential

    Arushi Bodas🇺🇸 · Edward Broadberry🇺🇸 · Raman Sundrum🇺🇸 · Zhaohui Xu🇺🇸

    Cosmological collider physics allows the detection of heavy particles at inflationary scales through their imprints on primordial non-Gaussianities. We study the chemical potential mechanism applied to a pair of charged scalars. We analytically evaluate the resulting one-loop contribution to the bispectrum, using the spectral decomposition. In this way we are able to determine the parametric dependences for both the signal and the background. We show that a signal strength $f_{\mathrm{NL}}\sim O(0.01)$ can be obtained within theoretical control, potentially reachable by 21cm tomography. As an application we consider the colored Higgs bosons in $\mathrm{SU}(5)$ supersymmetric orbifold grand unification with masses $M\lesssim 10^{15}\mathrm{GeV}$.

    hep-phastro-ph.COJHEP(2026)·23 citations
21. 21*

    Hidden Sector Custodial Naturalness

    Thede de Boer🇩🇪 · Manfred Lindner🇩🇪 · Andreas Trautner🇵🇹

    Custodial Naturalness is a recently introduced idea that combines conformal and scalar-sector custodial symmetry to address the electroweak (EW) scale hierarchy problem of the Standard Model (SM). We introduce a new model that realizes Custodial Naturalness without extension of the SM gauge group. The number of new dynamical degrees of freedom is minimized and the custodial symmetry is reduced to $\mathrm{SO}(5)$. This requires a new scalar singlet field that automatically is a good Dark Matter (DM) candidate, produced via freeze-in with moderate couplings. The most minimal scenario allows the quantum critical generation of the EW scale in a phenomenologically viable way requiring a UV completion at around $10^{11}\mathrm{GeV}$. Including ingredients for neutrino mass generation can push this scale to $M_{\mathrm{Pl}}$.

    hep-phhep-exPRL(2026)·2 citations
22. 22*

    An $N$-independent tensor decomposition for SU($N$)

    Stefan Keppeler🇩🇪 · Malin Sjodahl🇸🇪 · Bernanda Telalovic🇩🇰

    To facilitate a simultaneous treatment of an arbitrary number of colors in representation theory-based descriptions of QCD color structure, we derive an $N$-independent reduction of SU($N$) tensor products. To this end, we label each irreducible representation by a pair of Young diagrams, with parts acting on quarks and antiquarks. By combining this with a column-wise multiplication of Young diagrams, we generalize the Littlewood-Richardson rule for the product of two Young diagrams to the product of two Young diagram pairs, achieving a general-$N$ decomposition.

    hep-phhep-thmath-phmath.MP+1JHEP(2026)·0 citations
23. 23*

    Neutrino-Mass-Driven Instabilities as the Earliest Flavor Conversion in Supernovae

    Damiano F. G. Fiorillo🇩🇪 · Hans-Thomas Janka🇩🇪 · Georg G. Raffelt🇩🇪

    Collective neutrino flavor conversions in core-collapse supernovae (SNe) begin with instabilities, initially triggered when the dominant ${\nu }_e$ outflow concurs with a small antineutrino flux of opposite lepton number, with ${\overline{\nu }}_e$ dominating over ${\overline{\nu }}_{\mu }$. When these "flipped" neutrinos emerge in the energy-integrated angular distribution (angular crossing), they initiate a fast instability. However, before such conditions arise, spectral crossings typically appear within $20\mathrm{ms}$ of collapse, i.e., local spectral excesses of ${\overline{\nu }}_e$ over ${\overline{\nu }}_{\mu }$ along some direction. Therefore, post-processing SN simulations cannot consistently capture later fast instabilities because the early slow ones have already altered the conditions.

    hep-phastro-ph.COastro-ph.HEPRL(2025)·29 citations
24. 24*

    Lepton number crossings are insufficient for flavor instabilities

    Damiano F. G. Fiorillo🇩🇪 · Georg G. Raffelt🇩🇪

    In dense neutrino environments, the mean field of flavor coherence can develop instabilities. A necessary condition is that the flavor lepton number changes sign as a function of energy and/or angle. Whether such a crossing is also sufficient has been a longstanding question. We construct an explicit counterexample: a spectral crossing without accompanying flavor instability, with an even number of crossings being key. This failure is physically understood as Cherenkov-like emission of flavor waves. If flipped-lepton-number neutrinos never dominate among those kinematically allowed to decay, the waves cannot grow.

    hep-phastro-ph.COastro-ph.HEPRL(2026)·14 citations
25. 25*

    Self-consistent graviton spectral function in Lorentzian quantum gravity

    Jan M. Pawlowski🇩🇪 · Manuel Reichert🇬🇧 · Jonas Wessely🇩🇪

    We present the first fully self-consistent computation of the graviton spectral function in quantum gravity, using the spectral renormalisation group for gravity put forward in arXiv:2111.13232v2 [hep-th] within a physical mass-shell renormalisation scheme. Here, self-consistency refers to the fact that the full non-perturbative spectral function is used in the diagrams, including the scattering continuum. We find a positive graviton spectral function with a massless one-graviton peak and a multi-graviton continuum with a close-to-quadratic spectral decay in the ultraviolet. Within the physical on-shell renormalisation scheme, the graviton satisfies the sum rule of an asymptotic state and features a unit total spectral weight. We briefly discuss the implications of the physical formulation for the computation of scattering processes and investigations of unitarity in asymptotically safe quantum gravity.

    ↳ hep-thgr-qchep-phPLB(2026)·17 citations
26. 26*

    Low-energy multi-photon scattering at tree-level and one-loop order in a homogeneous electromagnetic field

    Ivan Ahumada🇬🇧 · Patrick Copinger🇬🇧 · James P. Edwards🇬🇧

    We study low energy photons coupled to scalar and spinor matter in the presence of an arbitrary homogeneous electromagnetic field in a first-quantised (worldline) approach. Utilising a Fock-Schwinger gauge for both the scattering photons and homogeneous background, simple compact expressions are found for both the photon- and background-dressed effective action and propagator in scalar and spinor quantum electrodynamics. The low-energy limit allows identification of the coupling of the scattering photons as one of an effective homogeneous superposition of their field strengths, with amplitudes following from application of a suitable linearisation operator. To treat the linearisation, several techniques are employed, including a functional expansion based on the proper time formalism and worldline Green functions, linearised vertex operators under a worldline path integral, and a matrix expansion in the field strengths. We find, in particular, that a replacement rule converting scalar amplitudes to spinor amplitudes at one-loop order can, surprisingly, be extended to tree level amplitudes in the low energy limit. Finally, we discuss a novel worldline representation of the momentum space matter propagators, obtaining a suitable worldline Green function for this path integral satisfying homogeneous Dirichlet boundary conditions and momentum space vertex operators representing the scattering photons already in momentum space.

    ↳ hep-thhep-phPRD(2025)·4 citations
27. 27*

    The $\theta$-vacuum from functional renormalisation

    Yuepeng Guan🇨🇳 · Jan M. Pawlowski🇩🇪 · Masatoshi Yamada🇯🇵

    We study topological properties of a quantum mechanical system with $U(1)$-symmetry within the functional renormalisation group (fRG) approach. These properties include the vacuum energy structure and the topological susceptibility. Our approach works with a complexification of the flow equation, and specifically we embed the original symmetry into the complex plane, $U(1)\to \mathbb{C}$. We compute the effective potential of a given topological sector by restricting ourselves to field configurations with a given generalised non-trivial Chern-Simons numbers. The full potential is directly constructed from these sector potentials. Our results compare well with the benchmark results obtained from solving the corresponding Schrödinger equation.

    ↳ hep-thhep-phquant-phPRD(2026)·1 citation
28. 28*

    Dark sector search at BESIII

    Zhijun Li🇨🇳 · Zhengyun You

    The Standard Model has achieved significant success in particle physics; however, there are still some unresolved puzzles beyond it. This motivates the exploration of the dark sector. We present the recent dark sector search results from BESIII experiment, which include the search for axion-like particles in the $J/\psi$ data set, the search for muon-philic particles in muon radiation, the search for massless dark photons in $D^0\to \omega {\gamma }^{\prime }$ and $D^0\to \gamma {\gamma }^{\prime }$, and the search for invisible decays of $K_S^0$.

    ↳ hep-exhep-phPoS(2026)·0 citations
29. 29*

    Stochastic-tail of the curvature perturbation in hybrid inflation

    Tomoaki Murata🇯🇵 · Yuichiro Tada🇯🇵

    The exponential-tail behaviours of the probability density function (PDF) of the primordial curvature perturbation are confirmed in the mild-waterfall variants of hybrid inflation with the use of the stochastic formalism of inflation. On top of these tails, effective upper bounds on the curvature perturbation are also observed, corresponding to the exact hilltop trajectory during the waterfall phase. We find that in the model where the leading and higher-order terms in the expansion of the inflaton potential around the critical point are fine-tuned to balance, this upper bound can be significantly reduced, even smaller than the primordial black hole (PBH) threshold, as a novel perturbation-reduction mechanism than the one proposed by Tada and Yamada. It makes PBH formation much difficult compared to the Gaussian or exponential-tail approximation. We also introduce Johnson's $S_U$-distribution as a useful fitting function for the PDF, which reveals a nonlinear mapping between the Gaussian field and the curvature perturbation.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2026)·13 citations
30. 30*

    Anomalous dimensions and critical exponents for the Gross-Neveu-Yukawa model at five loops

    J.A. Gracey🇬🇧 · A. Maier🇪🇸 · P. Marquard🇩🇪 · Y. Schröder🇨🇱

    We renormalize the Gross-Neveu-Yukawa model with an $O(N)$ symmetry to $\mathcal{O}({ϵ}^5)$ in $d=4-ϵ$ dimensions and determine the anomalous dimensions of the fermion and scalar fields, $\beta$-functions as well as the scalar field's mass operator. These are used to construct several $N$ dependent critical exponents relevant for quantum transitions in semi-metals and in particular those connected with graphene in three dimensions when $N=2$. Improved exponent estimates for scalar fermion transitions on a honeycomb lattice, when $N=1$, as well as for $N=5$ are also given to compare with results from other techniques such as the conformal bootstrap.

    ↳ hep-thcond-mat.str-elhep-phPRD(2025)·16 citations
31. 31*

    The influence of electromagnetic fields on the generation of the directed and elliptic flows of heavy quark in relativistic heavy-ion collisions

    Santosh K. Das🇮🇳 · Olga Soloveva🇩🇪 · Taesoo Song🇩🇪 · Elena Bratkovskaya🇩🇪

    We study the impact of self-generated electromagnetic fields (EMF) on the charm quarks momentum evolution in the partonic and hadronic medium created in heavy-ion collisions at RHIC energy within the Parton-Hadron-String Dynamics (PHSD) off-shell transport approach. In the quark-gluon plasma (QGP) phase, the charm quark interacts with the off-shell partons whose mass and widths are given by the Dynamical Quasi-Particle Model (DQPM), which can reproduce the lattice QCD thermodynamics. The background electromagnetic fields are computed dynamically within the PHSD considering both the spectators and participants protons as well as newly produced charged hadrons, quarks, and antiquarks, which reflects naturally the electric conductivity ${\sigma }_{el}$ of the medium. We study the directed and elliptic flow of the $D$ mesons in the presence of the electromagnetic fields. We find that electromagnetically induced splitting in the $D$ meson $v_1$ through $D^0$ and ${\overline{D}}^0$ mesons is consistent with the experimental data. Furthermore, we notice that the splitting in the heavy quark $v_1$ as a function of $p_T$ is more prominent as a probe of the produced electromagnetic fields. However, we find only a small impact of electromagnetic fields on the heavy quark elliptic flow $v_2$.

    ↳ nucl-thhep-phnucl-exPRC(2025)·4 citations
32. 32*

    Tensor induced gravitational waves

    Fei-Yu Chen🇨🇳 · Jing-Zhi Zhou🇨🇳 · Di Wu🇨🇳 · Zhi-Chao Li🇨🇳 · Peng-Yu Wu🇨🇳

    Primordial gravitational waves on small scales are not tightly constrained by current cosmological observations, which allows for the possibility of large amplitudes at small scales. We investigate second-order tensor induced gravitational waves (TIGWs) sourced by primordial gravitational waves and present the corresponding corrections to the total energy density spectrum of gravitational wave. We analyze primordial gravitational waves with large amplitudes generated by various models at small scales. Our results indicate that when primordial gravitational waves on small scales sufficiently dominate the current PTA observations, corrections to the total energy density spectrum from second-order TIGWs may become pronounced in certain frequency bands.

    ↳ astro-ph.COgr-qchep-phhep-th1 citation
33. 33*

    Gauge Choices, Infrared Pitfalls, and Thermal Effects in Effective Potentials

    Debanjan Balui🇮🇳 · Tisa Biswas🇮🇳 · Joydeep Chakrabortty🇮🇳 · Debmalya Dey🇮🇳 · Christoph Englert🇬🇧 · Subhendra Mohanty🇮🇳

    The evaluation of effective potentials is critical for a range of phenomenological applications, including inflation, vacuum stability, and phase transitions. A drawback arises from the gauge-dependence of the effective potential. Furthermore, in theories with spontaneous symmetry breaking, the effective potential exhibits infrared (IR) divergences in the limit of vanishing Goldstone masses. By considering the multiplicative anomaly that arises due to non-factorisation of elliptic operators in the Fermi gauge when computing the effective potential at one-loop order, we demonstrate that its gauge independence and IR behaviour are improved to the corresponding findings of Landau gauge calculations simultaneously. The latter are straightforwardly and transparently reproduced using an approach that employs the Heat Kernel technique, thereby providing a shortcut to reflect anomaly-related cancellations from the outset. Our findings generalise to the treatment of the effective potential at finite temperature. In particular, the Heat Kernel extends gauge independence to any value of the expansion in mass over temperature.

    ↳ hep-thhep-exhep-phPRD(2025)·8 citations
34. 34*

    Thermodynamics of a Spherically Symmetric Causal Diamond in Minkowski Spacetime

    Kwinten Fransen🇺🇸 · Temple He🇺🇸 · Kathryn M. Zurek🇺🇸

    We compute a gravitational on-shell action of a finite, spherically symmetric causal diamond in $(d+2)$-dimensional Minkowski spacetime, finding it is proportional to the area of the bifurcate horizon $A_{\mathcal{B}}$. We then identify the on-shell action with the saddle point of the Euclidean gravitational path integral, which is naturally interpreted as a partition function. This partition function is thermal with respect to a modular Hamiltonian $K$. Consequently, we determine, from the on-shell action using standard thermodynamic identities, both the mean and variance of the modular Hamiltonian, finding $⟨K⟩=⟨(\Delta K{)}^2⟩=\frac{A_{\mathcal{B}}}{4G_N}$. Finally, we show that modular fluctuations give rise to fluctuations in the geometry, and compute the associated phase shift of massless particles traversing the diamond under such fluctuations.

    ↳ hep-thgr-qchep-phJHEP(2025)·7 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.