Tue·May 5, 2026Tuesday·May 5, 2026

1. 01*

   Three-flavor supernova neutrino simulation using a hybrid quantum-classical algorithm with qutrits

   Daniel J. Heimsoth🇺🇸 · A. Baha Balantekin🇺🇸 · Pooja Siwach🇺🇸

   We simulate a self-interacting three-flavor neutrino system within a core-collapse supernova using a hybrid classical-quantum algorithm on a qutrit computer. Based on the Dirac-Frenkel evolution equations, we employ a variation of the quantum-assisted simulator to calculate the system's time evolution operator by performing qutrit Hadamard tests to find expectation values of unitary operators in the Hamiltonian. The time evolution simulation is then done classically. We find that the hybrid algorithm produces results comparable to an exact numerical integration out to times of $t\approx 30{\omega }_0^{-1}$ with time step $\delta t=0.005{\omega }_0^{-1}$, where ${\omega }_0$ is the energy scale of the single neutrino vacuum oscillations. We discuss the lessons learned in simulating neutrino systems using this hybrid quantum-classical algorithm, along with the advantages it offers over quantum Trotterization.

   hep-phastro-ph.HEastro-ph.SRnucl-th+1PRD(2026)·3 citations
2. 02*

   Gravitational waves from CP domain wall collapse and electron EDM in a complex singlet model with dimension-five Yukawa interactions

   Hieu The Pham🇹🇼 · Eibun Senaha

   We study the interplay between gravitational waves (GWs) from domain wall collapse and the electron electric dipole moment (EDM) in a complex singlet extension of the standard model with dimension-five Yukawa interactions. In this framework, the scalar potential admits CP-related degenerate vacua, leading to the formation of CP domain walls. While the resulting GW signal provides a probe of the vacuum structure of the singlet scalar sector, it does not by itself constitute a CP-violating observable. Once the singlet scalar is coupled to standard model fermions, CP-violating phases become observable through EDMs. We analyze whether current and future EDM experiments can probe the parameter region where the GW signal is detectable by SKA and THEIA. We find that the current electron EDM bound already constrains part of the parameter space, while future sensitivities at the level of $10^{-31}$--$10^{-32}e\mathrm{cm}$ can probe regions overlapping with the GW-detectable domain. Our results highlight the complementarity between GW and EDM observables in probing the singlet scalar sector, providing a coherent picture of its vacuum structure and CP properties.

   hep-ph0 citations
3. 03*

   Multi-Lepton Probes of the Drell-Yan Production of Triplet Higgses

   Siddharth P. Maharathy🇿🇦 · Srimoy Bhattacharya🇿🇦 · Andreas Crivellin🇪🇸 · Mukesh Kumar🇿🇦 · Rachid Mazini🇿🇦 · Bruce Mellado🇿🇦

   Excesses in di-photon, $Z\gamma$, and $WW$ spectra indicate the existence of a new Higgs boson with mass $152\pm 1$ GeV. However, no excess is observed in the $ZZ$ channel. This pattern aligns with a Real Higgs Triplet model with hypercharge $Y=0$ ($\Delta$SM). A prediction of this model is the Drell--Yan production of scalars at the LHC, which dominantly decay to electroweak bosons, thus enhancing the cross sections of triboson channels such as $WWZ$, $WZZ$, and $WWW$. Interestingly, both ATLAS and CMS have reported higher-than-expected significances for such processes: $6.4\sigma$ (observed) vs $4.7\sigma$ (expected) in the $VVZ$ (where $V=W$ or $Z$) channel and $4.4\sigma$ vs $3.6\sigma$ in $WWZ$, suggesting the possibility that these signals may be manifestations of an extended Higgs sector. We investigate whether the $\Delta$SM can account for these triboson excesses through electroweak production and decay of triplet scalars. We find that while current data prefers a non-zero new physics signal ($2.6\sigma$), the $\Delta$SM predicts more events than observed, such that it is consistent with data but not preferred over the SM. However, this tension could be clarified with Run~3 and HL-LHC data.

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

   Effects of the magnetic field on ${\pi }^0$ production in ultraperipheral Pb-Pb collisions

   C.N. Azevedo🇧🇷 · R. Fariello🇧🇷 · F.C. Sobrinho🇧🇷 · F.S. Navarra🇧🇷

   In this work, we study the effect of the magnetic field on the production of neutral pions in photon-photon interactions in ultraperipheral Pb-Pb collisions at the LHC. The calculation is performed within the equivalent photon approximation, including a magnetic-field dependence in the decay width $\Gamma ({\pi }^0\to \gamma \gamma )$, from which the corresponding production cross section is computed. We find that the reduction of the two-photon decay width in the presence of a strong magnetic field leads to a substantial reduction (by a factor of about 2-3) of the ${\pi }^0$ production cross section at LHC energies.

   hep-ph0 citations
5. 05*

   Probing Saturation Effect in Heavy Meson Pair Correlation in Forward $pA$ Collisions

   Zhan Gao🇨🇳 · Cyrille Marquet🇫🇷 · Yu Shi🇨🇳 · Bo-Wen Xiao🇨🇳

   Forward two-particle angular correlations in $pA$ collisions have long been recognized as a particularly sensitive observable for exploring gluon saturation effects. In the back-to-back regime, two-particle correlations receive substantial contributions from both soft-gluon radiation and saturation effects. In this work, we study heavy meson pair correlation in forward proton-nucleus collisions by incorporating a unified Sudakov resummation for heavy meson pair correlations in the Color Glass Condensate effect theory. Our results are in good agreement with the $\Delta \varphi$ data measured by the LHCb Collaboration for $D^0{\bar{D}}^0$ pairs in forward $pp$ and $pA$ collisions, as well as $J/\psi$ pairs from $b\bar{b}$ decays in forward $pp$ collisions. Furthermore, we present predictions for $D\bar{D}$ and $B\bar{B}$ correlations in the forward rapidity regions at the Large Hadron Collider. A pronounced mass-hierarchy is observed in the nuclear modification factor, $R_{pA}{|}_{m_b}<R_{pA}{|}_{m_c}$, indicating stronger sensitivity to saturation effects at small $x$. As the rapidity increases, the suppression becomes more pronounced while the mass hierarchy remains robust. This study will help us to search for the saturation signal via heavy-meson pair correlations in forward $pA$ collisions.

   hep-phhep-exhep-thnucl-th7 citations
6. 06*

   Multimodal Fragmentation of All-Heavy Pentaquarks: Uncertainty-Aware Predictions for Hadron Colliders

   Francesco Giovanni Celiberto🇪🇸

   We present an uncertainty-aware description of leading-power fragmentation for all-charm pentaquark states ($S$-wave $|cccc\bar{c}⟩$) at hadron colliders. We construct a multimodal set of collinear fragmentation functions, PQ5Q1.1, incorporating both perturbative and nonperturbative uncertainties. Perturbative effects are estimated via missing higher-order variations (F-MHOUs), while the nonperturbative wave function is modeled through controlled modifications of its transverse-momentum structure (F-NPWF), consistently combined within a replica-like framework. The initial-scale input for constituent charm fragmentation is refined to describe both compact multiquark and diquark-driven production mechanisms. We employ the (sym)JETHAD interface to study NLL/NLO${}^{+}$ semi-inclusive pentaquark-plus-jet production at the HL-LHC and future FCC. The bottom sector is left to future dedicated studies due to its enhanced sensitivity to nonperturbative modeling. Our results provide a flexible framework for uncertainty-controlled predictions, bridging exotic-hadron structure, heavy-flavor fragmentation, and high-energy QCD.

   hep-phhep-exhep-thnucl-ex+1PRD(2026)·3 citations
7. 07*

   Equation of State of Dense Matter: Pauli Degeneracy, Pairing Correlations, and Implications for Neutron Stars

   Yaroslav D. Krivenko-Emetov🇦🇹 · Gleb Shabal🇦🇹

   We develop a unified description of dense fermionic matter that consistently incorporates Pauli degeneracy, interaction effects, and pairing correlations. The condition that the temperature is much smaller than the Fermi energy leads to a natural separation among the Sommerfeld, Fermi-liquid, and pairing regimes. We show how these contributions enter the equation of state. The resulting EOS is applied to the Tolman-Oppenheimer-Volkoff equations to analyze neutron-star structure. We demonstrate that Pauli degeneracy provides the dominant pressure, interactions determine the stiffness of the EOS, and pairing correlations produce subleading but potentially significant corrections, especially in quark matter. Implications for mass-radius constraints and modern observations are discussed. The quasiparticle interaction in the normal Fermi-liquid phase is parameterized by the isotropic Landau parameter F_0^s and linked explicitly to the compressibility and sound speed. The theoretical mass-radius curves are compared with four recent NICER measurements.

   hep-phnucl-th0 citations
8. 08*

   New Directions in Kaon Physics: Interference in $K^0\to {\mu }^{+}{\mu }^{-}$ as a New Golden Mode

   Teppei Kitahara🇯🇵

   The rare decays $K_L^0\to {\mu }^{+}{\mu }^{-}$ and $K_S^0\to {\mu }^{+}{\mu }^{-}$ have long been regarded as difficult channels to extract short-distance physics because they are dominated by long-distance contributions via two-photon exchanges. A qualitatively new feature arises once the interference between $K_L^0$ and $K_S^0$ is taken into account. The interference term is sensitive to genuine direct $CP$ violation in $s\to d{\mu }^{+}{\mu }^{-}$ processes and turns this channel into a clean probe of the $CP$-violating short-distance physics. In this contribution, I summarize the basic mechanism of the $K_L^0$--$K_S^0$ interference, the flavor-tagging strategy at LHCb-like setup, and the projected sensitivities for a kaon-unitarity-triangle parameter combination $|A^2{\lambda }^5\bar{\eta }|$ and also for the sign ambiguity of the $K_L^0\to \gamma \gamma$ three-point amplitude. As a result, it is expected that the CKM parameter $|A^2{\lambda }^5\bar{\eta }|$ could be constrained by LHCb at the level of about $35\%$ of its Standard Model (SM) value, and the discrete ambiguity in $\mathcal{B}(K_L^0\to {\mu }^{+}{\mu }^{-}{)}_{\mathrm{SM}}$ could be resolved at more than $3\sigma$ by the end of the high luminosity LHC.

   hep-phhep-ex0 citations
9. 09*

   Production Rate of Glueball-like $X(2370)$ in $J/\psi$ Radiative Decay

   Ying Chen🇨🇳 · Long-Cheng Gui🇨🇳 · Geng Li🇨🇳 · Wei Sun🇨🇳

   $X(2370)$ falls in the mass region of the lowest pseudoscalar glueball predicted by lattice QCD studies and its decay properties are similar to those of ${\eta }_c$. A previous lattice QCD study finds that the pseudoscalar glueball ($G_{0^{-}}$) and the lowest pseudoscalar charmonium ($c\bar{c}(0^{-})$) can mix with a small mixing angle $\sin \theta$. It is therefore possible that $X(2370)$ and ${\eta }_c$ are admixtures of $G_{0^{-}}$ and $c\bar{c}(0^{-})$. In this picture, although $\mathrm{Br}(J/\psi \to \gamma {\eta }_c)$ is insensitive to the small $\sin \theta$, $\mathrm{Br}(J/\psi \to \gamma X(2370))$ can be enlarged drastically by the mixing due to the much larger kinematic factor for $J/\psi \to \gamma X(2370)$ and the much larger transition form factor for $J/\psi \to \gamma (c\bar{c}(0^{-}))$. Depending on the value of $\sin \theta$, $\mathrm{Br}(J/\psi \to \gamma X(2370))$ can be much larger than that of the pure pseudoscalar glueball, namely, $2.3(8)\times 10^{-4}$ that is predicted by a quenched lattice QCD calculation. Present results by BESIII favor a small mixing angle of $\mathcal{O}(1^{\circ })$, which can be further constrained by more measurements of $X(2370)$ decays if the mixing picture applies here.

   hep-phhep-lat4 citations
10. 10*

    Transverse momentum dependence of $\Omega /\varphi$ ratio in high energy collisions

    Hai-hong Li🇨🇳 · Jun Song🇨🇳 · Feng-lan Shao🇨🇳

    We apply a constituent quark equal-velocity combination model to study the $p_T$ dependence of $\Omega /\varphi$ ratio in $pp$, $p$-Pb and Pb-Pb collisions at LHC energies. We demonstrate that the relative change rate of the $\Omega /\varphi$ ratio is dominated by a discrete curvature property of $p_T$ spectrum of strange quarks just before hadronization. Using experimental data of $\varphi$ mesons after a quark number scaling operation, we extract $p_T$ spectrum of strange quarks just before hadronization and study its curvature property in high and low multiplicity events in $pp$ collisions at $\sqrt{s}=$ 7, 13 TeV, $p$-Pb collisions at $\sqrt{s_{NN}}$= 5.02 TeV and Pb-Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV. We apply these curvature properties of $p_T$ spectra of strange quarks to explain the observed $p_T$ dependence of $\Omega /\varphi$ ratio in those collisions. We discuss the possible origin of the change of curvature property for $p_T$ spectra of strange quarks just before hadronization by considering the influence of strong collective flow formed in partonic stage evolution in collisions at LHC energies.

    hep-ph0 citations
11. 11*

    Boost-invariant and cylindrically symmetric perfect spin hydrodynamics

    Zbigniew Drogosz🇵🇱 · Wojciech Florkowski🇵🇱 · Jakub Witkowski🇵🇱

    Equations of a boost-invariant and cylindrically symmetric perfect hydrodynamics are solved numerically for initial conditions inspired by the wounded nucleon model. The energy-momentum and spin tensors are used in the form that describes a relativistic massive gas governed by Boltzmann statistics. In contrast to one dimensional boost-invariant expansion, we find a coupling between the azimuthal and longitudinal components of the electric and magnetic components of the spin polarization tensor. This feature is similar to that found earlier for the Gubser symmetry, however, our treatment allows for a more general form of initial conditions and expansion geometry. Defining the freeze-out hypersurface by the constant temperature condition, we evaluate the Pauli-Lubański four-vector and find that for the assumed geometry the only nonzero total polarization may be induced by the longitudinal component of the magnetic part of the spin polarization tensor coupled with the azimuthal electric component. The obtained results may serve as a reference point for more realistic models of hydrodynamic expansion.

    hep-phnucl-thPRC(2026)·0 citations
12. 12*

    Hunting for $B\bar{B}$ molecular state $X_{b0}$ via radiative transition of ${\rm Y}(10753)$

    Yuan-Jun Gao🇨🇳 · Gang Li🇨🇳 · Shi-Dong Liu🇨🇳 · Qi Wu🇨🇳

    We investigate the radiative decay ${\rm Y}(10753)\to \gamma X_{b0}$ within the framework of nonrelativistic effective field theory (NREFT). The ${\rm Y}(10753)$ is treated as an $S$-$D$ mixed state of the ${\rm Y}(4S)$ and $\text{YD}$, while the $X_{b0}$ is interpreted as a weakly bound $B\bar{B}$ molecule with $J^{PC}=0^{++}$. The decay process was assumed to occur via the intermediate meson loops involving the $S$-wave $B^{(\ast )}$ and $P$-wave $B_1^{(\prime )}$ mesons. Our calculated results indicate that the decay ${\rm Y}(10753)\to \gamma X_{b0}$ is dominated by the $B_1^{(\prime )}$ meson loops. The partial decay width is predicted to be $0.2-1.5\mathrm{keV}$ for a binding energy range of ${ϵ}_X=0-10\mathrm{MeV}$, corresponding to a branching fraction of $10^{-6}-10^{-5}$. The decay width is found to be insensitive to the full width of the $B_1^{\prime }$ meson. Our study suggests that the radiative decay of the ${\rm Y}(10753)$ is a promising channel to search for the $X_{b0}$ state, which is crucial for testing heavy-quark symmetries and understanding the exotic hadron spectrum in the bottom sector.

    hep-phPRD(2026)·0 citations
13. 13*

    Twist-3 transverse momentum dependent gluon distributions in a spectator model

    Xiupeng Xie🇨🇳 · Zhun Lu🇨🇳

    We study the twist-3 transverse momentum dependent distributions of gluons in a nucleon within a spectator model framework. In this model, the nucleon is described as emitting a virtual (time-like) gluon and an on-shell spectator particle, with the spectator mass treated continuously via a spectral function. The twist-3 gluon-gluon correlators, ${\Phi }^{+i;+-}$ and ${\Phi }^{ij;l+}$, are parameterized by a set of complex functions, whose real and imaginary parts correspond to T-even and T-odd components, respectively. We numerically check the equation of motion relation for these distributions and find that relation holds fairly well in the spectator model.

    hep-phEPJC(2026)·0 citations
14. 14*

    Non-Holomorphic Impact on $t-b-\tau$ Yukawa Unification in minimal GMSB

    Ali Çiçi🇹🇷 · Büşra Niş🇹🇷 · Cem Salih Ün🇹🇷

    We study and explore the low scale implications of Yukawa unification in the minimal gauge mediated supersymmetry breaking models. We also assume non-zero non-holomorphic terms, with which the YU solutions can be accommodated in the cases with $\mu >0$. These results can be considered a direct effect from the non-holomorphic terms, but they also lead to testable low scale implications compatible with YU. We observe abundant solutions consistent with the Higgs boson mass. This constraint leads to heavy strongly interacting supersymmetric particles, while the electroweak sector can be relatively light and they can be probed by several experiments. We find that the chargino can be lighter than 1 TeV and it is degenerate with the lightest neutralino in most of these solutions. Consistent solutions in this region can accommodate charginos as light as about 120 GeV, and they will likely be tested soon by the analyses over the compressed spectra. These solutions are also subjected in the lifetime analyses. Our analyses identify such light charginos as decaying in about $10^{-2}$ ns. Probing such points may need a slight improvement in the sensitivity of current analyses, and one can expect them to be tested very soon. In the same region, the stau is found to be another light supersymmetric particle, and some of the solutions can be inconsistently lighter. We find that it can weigh as light as about 600 GeV consistently, and it can be tested also soon over its lifetime. We summarize and also exemplify our findings with five benchmark scenarios. Furthermore, the benchmark solutions also reveal that the solutions can be tested in heavy Higgs boson searches, which shape the whole Higgs boson spectrum in models.

    hep-phPRD(2026)·0 citations
15. 15*

    Pair creation via Amplitude-Modulated Periodic and Quasiperiodic Pulse Sequences

    Deepak Sah🇮🇳

    We study nonperturbative pair production driven by alternating-sign electric field pulse trains. Using a quantum kinetic approach, we analyze both the longitudinal momentum spectrum and the particle yield for pulse sequences with either strictly periodic temporal structure, in which the pulse amplitudes alternate in a regular and repeating (E_1, E_2) pattern, or quasiperiodic (Fibonacci-ordered) structure, where the amplitudes follow a deterministic but aperiodic sequence generated by the Fibonacci substitution rule, exhibiting long-range order without exact repetition. For N=12 pulses, periodic trains generate regularly modulated spectra characteristic of multi-slit (Ramsey-type) interference, whereas Fibonacci sequences produce fragmented structures and partial momentum-space localization. Increasing the pulse number to N=20 further enhances these effects: periodic driving yields sharper and higher-contrast interference fringes, while quasiperiodic ordering leads to stronger localization and increasingly irregular spectral features.The particle yield exhibits a strongly nonlinear dependence on the field-strength ratio. For weak modulation , both temporal orderings produce nearly identical yields. For stronger fields, a modest crossover behavior is observed, with quasiperiodic sequences yielding slightly larger values than the periodic case. Overall, temporal ordering primarily redistributes spectral weight in momentum space, while the integrated yield is governed predominantly by the effective field strength. These results establish long-range temporal ordering as an effective control parameter in multipulse Schwinger pair production and provide guidance for designing tailored pulse sequences in future high-intensity laser experiments.

    hep-phhep-th0 citations
16. 16*

    Detectability of Magnetar-Induced Vacuum Birefringence with IXPE and eXTP

    Fayez Abu-Ajamieh🇮🇳

    We analyze the prospects of quantitatively detecting vacuum birefringence from magnetars using the IXPE and eXTP experiments. We adopt a realistic profile to model the magnetic field of magnetars, and use it to calculate the time delay and phase difference in the parallel and perpendicular components of polarization eigenmodes using Adler's integral formula. We find that the time delay could be an order of magnitude larger than previous estimates in the literature. We also calculate the Stokes parameters for all known magnetars and show that both IXPE and eXTP are capable of quantitatively measuring birefringence from magnetars, with the magnetar dubbed 1RXS J170849.0-400910 being the best candidate for detection.

    hep-ph2 citations
17. 17*

    How neutrinos could help solving cosmological anomalies and tensions

    Pasquale Di Bari🇬🇧

    In this talk I discuss how neutrinos might help solving or alleviating different anomalies and tensions in cosmology. Invisible decays of the heaviest relic neutrinos might provide a way to solve the neutrino mass tension between cosmological observations and neutrino oscillation experiments. The excess radio background mystery could be explained by radiative decays of relic neutrinos. However, the upper bound on the neutrino effective magnetic moment requires some trick to be circumvented. To this extent, I discuss a recently proposed boomerang mechanism in which the visible sector throws dark neutrinos into the dark sector at $t\sim 100\mathrm{s}$ and $T\sim 100\mathrm{keV}$, and much later (basically at the present time) the dark sector throws back photons into the visible sector. The mechanism predicts an effective neutrino magnetic moment that might be within the reach of next experiments. Some contribution to the 21 cm cosmological signal is also expected. These are exciting times for cosmological searches of BSM physics.

    hep-ph0 citations
18. 18*

    Studying the Infrared Behaviour of Improved Logarithmic Accuracy Parton Showers with Herwig

    Jack Holguin🇬🇧 · Simon Plätzer🇦🇹 · Michael H. Seymour🇬🇧 · Siddharth Sule🇬🇧

    We have implemented two recently proposed dipole shower algorithms that have next-to-leading-logarithmic accuracy at leading colour in the Herwig event generator. We study their properties and compare them to Herwig's existing dipole and angular ordered parton shower algorithms. In addition to their improved properties in the logarithmic regime, we find important roles for their extrapolations into the hard regime, where we perform NLO matching, and into the infrared regime, where we perform cluster hadronization. We emphasise the importance of this infrared regime and the precise definition of the infrared cutoff used by each shower as the initial state for Herwig's hadronization model. Studying the results at the hadron level, we find important consequences of this infrared cutoff difference and propose it as a starting point for further study of the interplay between parton showers and hadronization models. We conclude by studying the models' tunability and identifying the best-fit parameters for each.

    hep-phJHEP(2026)·0 citations
19. 19*

    Axion electron-electron interaction in the RaOH molecule to search for Dark matter

    Mikhail Reiter🇷🇺 · Anna Zakharova🇷🇺

    Axions are promising candidates for the role of Dark matter particles. In this paper, the question of the suitability of the RaOH molecule for the experimental detection of electron-electron interactions through the exchange of axions is studied. To take into account an impact of the rotations and vibrations a computation must be performed for a large number of molecular configurations. In this work we study this problem using a combination of the Generalized relativistic effective core potential and One-center restoration technique of the correct four-component spinors.

    hep-phphysics.atom-phphysics.chem-phquant-ph0 citations
20. 20*

    Collins asymmetries for pion-in-jet production in polarized $\ell p$ collisions at the EIC

    Umberto D'Alesio🇮🇹 · Carlo Flore🇮🇹 · Marco Zaccheddu🇺🇸

    We study Collins azimuthal asymmetries for pion-in-jet production in polarized lepton-proton collisions, extending previous analyses of polarized $pp$ scattering to a complementary and theoretically simpler process. We keep adopting a simplified transverse momentum dependent (TMD) approach, with a collinear configuration for the initial state, and employ the transversity and Collins fragmentation functions as extracted from semi-inclusive deep inelastic scattering and $e^{+}{e}^{-}$ annihilation processes. We then compute azimuthal asymmetries for the Electron-Ion Collider (EIC) kinematics, both within a leading order (LO) approach and by including quasireal photon exchange in the Weizsäcker-Williams approximation. Although this contribution is relevant in the whole kinematical range explored, it does not spoil the dominance of quark-initiated channels, leaving only a marginal role to their gluon counterparts. In this respect, Collins asymmetries in lepton-proton processes allow for a much clearer access to the transversity distribution, including its sea-quark component. As we will argue, a comparison with future EIC data could represent a further step in testing the hypothesis of the universality of the Collins function as well as of the TMD factorization for this class of processes.

    hep-phPLB(2026)·1 citation
21. 21*

    Spontaneous Symmetry Breaking and the Emergent Einstein-Standard Model: From Weyl x SU (2)L x U (1)Y Gauge Theory to Geometric Mass Generation

    Hao-Qian Peng · Yun-Tao Gu · Yu-Xiao Liu

    We construct a Weyl x SU(2)_L x U(1)_Y invariant theory by extending four-dimensional Weyl quadratic gravity with Weyl-invariant scalar, fermion, Yukawa and gauge sectors. The quadratic structure (R^tilde - mu^2 |phi|^2)^2 allows the Weyl Goldstone mode to be extracted via a Stueckelberg mechanism independent of the Higgs field. Spontaneous breaking of Weyl gauge symmetry reduces the Weyl quadratic curvature to the Einstein-Hilbert action with a positive cosmological constant, generates a mass term for the Weyl gauge field, and simultaneously produces the Higgs potential -mu^2 |phi|^2 + lambda^2 |phi|^4, which is otherwise forbidden by the symmetry. Our framework unifies the Stueckelberg, Higgs and Yukawa mechanisms, reproduces Standard Model mass generation, and predicts additional Higgs-induced contributions to the Weyl gauge field mass, together with a set of Higgs-Weyl couplings. These interactions provide new phenomenological handles, including a vector dark matter candidate, and highlight the geometric origin of mass.

    hep-phgr-qchep-th0 citations
22. 22*

    Calculating extremely high energy bremsstrahlung in matter

    Peter Arnold🇺🇸 · Joshua Bautista🇺🇸 · Omar Elgedawy🇨🇳 · Shahin Iqbal🇵🇰

    Ultra-relativistic electrons initiate electromagnetic showers in ordinary matter that evolve through bremsstrahlung and pair production. At very high energy, the quantum mechanical duration of bremsstrahlung becomes longer than the mean free time to elastically scatter from the medium, leading to a significant suppression known at the Landau-Pomeranchuk-Migdal (LPM) effect. For some ranges of bremsstrahlung photon and initial electron energies $(k_{\gamma },E)$, the duration becomes so long that it will also overlap with subsequent pair production by the bremsstrahlung photon, disrupting LPM suppression and drastically changing LPM predictions. We have previously calculated this change for extremely high energies ($k_{\gamma }\gg 2$ TeV or more, depending on the medium), for which the electron mass and medium-induced photon mass could be ignored. In this paper, we extend that analysis to lower (but still ultra-relativistic) energy by accounting for those masses, leading to a rich map of behavior in different regions of $(k_{\gamma },E)$.

    hep-phnucl-th1 citation
23. 23*

    Metastable strings at PTAs: classical stability analysis

    Simone Blasi🇩🇪 · Maxime Grandjean🇧🇪 · Alberto Mariotti🇧🇪

    Metastable strings can arise from a two-step symmetry breaking chain of the type $SU(2)\to U(1)\to 1$.They can decay through quantum tunneling by nucleating a monopole-antimonopole pair, and are prominent candidates for explaining the gravitational wave background detected at Pulsar Timing Arrays (PTAs).We investigate the classical stability of the strings arising in this commonly-considered setup, which serves as a fundamental input for discussing their possible decay channels. We identify the regions of parameter space in which the strings are either classically stable or unstable. Our results show that classical instabilities can impact the parameter space relevant for PTAs. We also discuss the possible fate of the string network in the regions of classical instability.

    hep-phastro-ph.CO4 citations
24. 24*

    Searching for UFOs from the early universe: direct detection prospects for relativistically decoupling dark matter

    Stephen E. Henrich🇺🇸 · Yann Mambrini🇫🇷 · Keith A. Olive🇺🇸

    Particles that decouple relativistically from the Standard Model bath during reheating represent a versatile class of well-motivated cold dark matter candidates. In fact, ultrarelativistic decoupling ($T_{\mathrm{FO}}\gg m_{\chi }$) is quite generic for beyond the Standard Model (BSM) heavy portal interactions with strong couplings and relatively low reheating temperatures. In this work, we study the direct detection prospects for ultrarelativistically frozen-out (UFO) candidates, using $Z^{\prime }$-portal dark matter as a case study. Although typical UFO cross sections are suppressed by a heavy mediator mass scale, we find that experiments such as LZ, XENONnT, PandaX, and DarkSide-50 have already excluded a large portion of the UFO parameter space and there remains viable space above the neutrino fog for $0.4\text{ GeV}\lesssim m_{\mathrm{DM}}\lesssim 1$ TeV. Moreover, SuperCDMS SNOLAB, which is expected to begin collecting data in 2026, should access a large region of UFO parameter space in the 0.5-10 GeV mass range. For heavy BSM portal interactions ($M\gtrsim 1$ TeV), UFOs are typically more accessible to detection than freeze-in candidates due to the comparatively larger cross sections. We also carefully delineate regions of parameter space with degeneracy between UFO and non-relativistic freeze-out. In sum, UFOs are attractive candidates for ongoing and next-generation dark matter detection experiments in a looming post-WIMP era.

    hep-phastro-ph.COhep-ex3 citations
25. 25*

    Closing the knowledge gap in semileptonic $B\to X_c\ell \nu$ decays

    Florian Herren🇨🇭 · Raynette van Tonder🇩🇪

    In this work we summarize the current status of measured exclusive semileptonic branching fractions containing charm mesons. We use the available experimental data to evaluate the difference between the sum of exclusive measurements and the inclusive determination. By including experimental results of branching fractions relative to semi-inclusive $B\to DX\ell \nu$ decays, we demonstrate that the unmeasured components of the total branching fraction are dominated by final states devoid of $D$ mesons, hinting towards sizeable contributions from baryonic final states and $D_s$ mesons. Based on the obtained fractions, we discuss candidates that could potentially close the remaining difference and propose searches for promising final states. Furthermore, we provide simplified models for S-wave $B\to D\eta \ell \nu$ and $B\to D_{s}K\ell \nu$ decays that contribute marginally to the unmeasured components of the total inclusive rate.

    hep-phhep-ex0 citations
26. 26*

    Formation and Redshift Evolution of Dark Matter Spikes

    Gonzalo Herrera🇺🇸 · Abdelaziz Hussein🇺🇸 · Lina Necib🇺🇸 · Elliot Y. Davies🇺🇸 · Xuejian Shen🇺🇸

    Dark matter density spikes forming around adiabatically growing black holes can dramatically enhance indirect and direct detection signals. Canonical predictions, however, assume a zero-mass seed in a purely dark matter environment and do not track the long-term dynamical impact of surrounding stars. We present a semi-analytic framework that first generalizes adiabatic spike formation to include finite seed masses, stellar cusps, and non-circular orbits, and then studies the subsequent cosmic evolution by solving coupled Fokker-Planck equations for the dark matter and stellar phase-space distributions, with a heating rate modulated by the cosmic star formation rate. Starting conservatively from canonical Gondolo-Silk spikes and marginalizing over astrophysical uncertainties, we find that stellar gravitational heating drives the inner slope towards ${\gamma }_{\chi }\simeq 1.5$ within a few Gyrs (e.g by $z\lesssim 2$ for spikes formed at $z\simeq 10$), yielding overdensities two to four orders of magnitude below canonical expectations but still well above an NFW-like cusp. We provide redshift-dependent benchmarks for the column density and $J$-factor relevant to scattering, decay and annihilation signatures. Any robust interpretation of indirect dark matter signals from galactic nuclei must account for this evolution.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ph3 citations
27. 27*

    Gravitational Waves from a Black Hole Falling Radially into a Thin-Shell Traversable Wormhole

    Mohammad Nosherwan Malik🇺🇸 · James B. Dent🇺🇸 · William E. Gabella🇺🇸 · Thomas W. Kephart🇺🇸

    We compute the gravitational-wave signal generated by the radial infall of a stellar-mass black hole into a thin-shell Schwarzschild traversable wormhole. Modeling the black hole as a test particle, we derive analytic expressions for the emitted waveform, including contributions from the mass quadrupole and higher-order multipoles. The resulting signal exhibits a characteristic pulse-gap structure associated with repeated throat crossings. We further compute the amplitude spectral density and compare it with representative ground-based detector sensitivities, finding that such signals could lie within the sensitivity range for optimally oriented sources at distances of order ~500 Mpc. These results provide a potential observational signature of traversable wormholes in gravitational-wave data.

    ↳ gr-qchep-ph1 citation
28. 28*

    Probing Quantum Entanglement in ${\tau }^{+}{\tau }^{-}$ Pairs via the $\pi \pi$ Channel at STCF

    Xiaokang Li🇨🇳 · Chentao Bao🇨🇳 · Hai Chen🇨🇳 · Mingyi Liu🇨🇳 · Dayong Wang🇨🇳

    Quantum entanglement and Bell-inequality violation in ${\tau }^{+}{\tau }^{-}$ pairs provide a sensitive probe of quantum correlations in high-energy interactions. We present a feasibility study of $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$ at the proposed Super Tau-Charm Facility based on full Monte Carlo simulation at $\sqrt{s}=7$ GeV, focusing on the $\pi \pi$ channel (${\tau }^{\pm }\to {\pi }^{\pm }\nu$), which offers the maximal spin-analyzing power $|\kappa |=1$ and the simplest final-state topology for validating the quantum-tomography framework. We establish a consistency chain from the tree-level QED prediction through truth-level and detector-level reconstruction, yielding a reconstructed concurrence of $0.279\pm 0.007$ with the good-solution approach. A complementary full-simulation study of the $\rho \rho$ channel is also briefly reported. These results demonstrate that the STCF can provide a competitive platform for precision studies of quantum correlations in $\tau$-lepton pairs.

    ↳ hep-exhep-phquant-ph1 citation
29. 29*

    Data-Driven, Geometry-Aware Optimal-Transport Calibration of Flavor Tagger

    Yeonjoon Kim🇰🇷 · Un-ki Yang🇰🇷

    Flavor-tagging calibrations are often provided either as scale factors measured at a finite set of working points or as binned corrections to a chosen one-dimensional discriminant. However, this approach falls short of providing continuous, event-level calibration across the full multicomponent outputs of modern taggers. This limitation leads to information loss in analyses that demand high-performance flavor tagging, restricting analyses to a limited set of predefined variables. In this work, we propose a geometry-aware framework that formulates flavor-tagger calibration as an optimal transport problem on the probability simplex. The transport maps are parameterized and trained in the isometric log-ratio coordinate system. Because the quadratic Euclidean cost of Brenier transport in this coordinate system is equivalent to the Aitchison distance on the simplex, the learned map induces a minimal deformation under the Aitchison geometry. Furthermore, we extract flavor-conditional target distributions directly from control-region data using an expectation-maximization (EM) technique that simultaneously fits multiple control regions, models each flavor component with a normalizing flow, and estimates the regional mixture fractions. The extracted targets are subsequently used to learn flavor-factorized transport maps. Because the joint estimation of mixture fractions and flexible component densities admits weakly constrained directions, we further introduce a linearized feedback-operator analysis that propagates the fitted composition covariance into the extracted component densities, separating data-constrained modes from those dominated by the composition prior. The simulation-based closure study demonstrates improved closure in dedicated control regions and in independent validation mixtures.

    ↳ hep-excs.LGhep-phstat.ME0 citations
30. 30*

    Relativistic BDNK MHD Evolution in a Boost-Invariant Medium and Its Impact on Dilepton Production

    Ankit Kumar Panda🇨🇳 · Rajesh Biswas🇵🇱

    In this work, we explore a Bemfica--Disconzi--Noronha--Kovtun (BDNK)-type formulation of relativistic magnetohydrodynamics, providing a causal and stable first-order description of dissipative fluids. We derive coupled evolution equations for the temperature and magnetic field in a boost-invariant Bjorken background, restricting to $(0+1)$D dynamics while retaining all relevant first-order gradients. By varying the transport coefficients, we disentangle the interplay and mutual backreaction between the thermal and electromagnetic sectors. We find that, for comparable transport coefficients, the magnetic field responds more strongly to changes in the temperature evolution, while its feedback on the temperature remains subleading. We further analyze the number density evolution, which is sensitive to both temperature gradients and magnetic-field dynamics. We also investigate implications for dilepton production, where the magnetic field modifies the emission rate via the relaxation time in a kinetic-theory framework. The coupled evolution leads to a suppression of the low-mass dilepton spectrum, primarily driven by enhanced cooling in the presence of positive coupling between temperature gradients and magnetic-field evolution, as compared to scenarios without such feedback.

    ↳ nucl-thhep-phPRD(2026)·0 citations
31. 31*

    Confinement of Massive Ghost in Quadratic Gravity

    Ichiro Oda🇯🇵

    In the framework of the covariant canonical formalism of quadratic gravity, we consider the problem of confinement of massive ghost which violates the unitarity of the physical S-matrix. It is shown that if there is a bound state between the massive ghost and Faddeev-Popov ghost the massive ghost is confined in the zero-norm states through the BRST quartet mechanism, thereby the unitarity being restored. Based on the superfield formulation by Bonora and Tonin, we show that the asymptotic field of the massive ghost must be a massive dipole whereas that of the bound state obeys a massive Klein-Gordon equation. This situation may be of some similarity to color confinement in quantum chromodynamics (QCD) where it is conjectured that not a massless but a massive gluon is in fact confined.

    ↳ hep-thgr-qchep-ph4 citations
32. 32*

    Gluon production in the Color Glass Condensate from BCFW recursion

    Francois Gelis🇫🇷

    In the Color Glass Condensate framework, the colliding projectiles are described as classical color currents. Gluon production at leading order in the coupling is obtained from the retarded solution of the classical Yang-Mills equations, with these currents acting as sources. However, while the final gluon spectrum is gauge invariant, the classical color field $A^{\mu }$ from which it is obtained is gauge dependent. This makes the intermediate steps of this approach unnecessarily complicated, as some effort is spent to also determine the gauge dependent part of $A^{\mu }$, which is then discarded when one calculates a gauge invariant observable. In this work, we use a generalization of BCFW recursion applicable to off-shell gluons in order to calculate directly the gauge independent gluon production amplitude. This approach allows all manipulations to be performed in terms of gauge invariant amplitudes instead of gauge dependent Feynman diagrams, and therefore provides a gauge agnostic way to obtain the result.

    ↳ nucl-thhep-phJHEP(2026)·0 citations
33. 33*

    Axion-mediated electron-electron interaction in RaOCH_3 molecule

    Anna Zakharova🇷🇺 · Mikhail Reiter🇷🇺

    We study the parity-violating electron-electron interaction mediated by the axion-like in the hexatomic molecule of a symmetric top type. The rich rovibrational behavior require electronic computations for multiple molecular configurations which can be reduced using Generalized Relativistic Effective Core Potential. To restore the correct behavior in the core region we use a one-center restoration technique generalized by us earlier to the two-electron properties. The property is averaged on the lowest-lying rovibrational states.

    ↳ physics.atom-phhep-ph0 citations
34. 34*

    Magnetic Monopoles -- From Dirac to the Large Hadron Collider

    Vasiliki A. Mitsou🇪🇸

    One of the basic properties of magnetism is that a magnet has always two poles, north and south, which cannot be separated into isolated poles, the magnetic monopoles. There are strong theoretical arguments in favour of monopoles' existence, but in spite of extensive searches they are yet to be found. In this review article, after highlighting briefly the theoretical foundations of monopoles, a historical overview of experimental endeavours to observe them is given, with emphasis on the state-of-the-art of searches in cosmic and collider experiments and in particular the Large Hadron Collider at CERN.

    ↳ hep-exhep-ph7 citations
35. 35*

    Finite-temperature operator basis on ${\mathbb{R}}^3\times S^1$ for SMEFT

    Joydeep Chakrabortty🇮🇳 · Bruno Siqueira Eduardo🇧🇷 · Siddhartha Karmakar🇮🇳 · Philipp Schicho🇨🇭

    We present the first complete non-redundant operator basis for the Standard Model Effective Field Theory (SMEFT) at finite temperature, using the imaginary-time formalism. By employing the Hilbert series method on the space-time manifold ${\mathbb{R}}^3\times S^1$, we classify all effective operators up to dimension-six. In constructing the basis, we consistently impose integration-by-parts and equations-of-motion constraints along spatial directions. We further analyze the impact of additional constraints, including the vanishing of the curl of the electric and magnetic fields and gauge choices for the temporal components on an operator basis. We also express them in terms of static three-dimensional spatial and zero-temperature SMEFT operators. At dimension five and six, we identify intrinsically thermal operators that vanish in zero temperature. Our framework is fully general and extends to arbitrary mass dimension and compact connected internal symmetry groups.

    ↳ hep-thhep-lathep-ph7 citations
36. 36*

    de Sitter Vacua & pUniverses

    Jeremias Aguilera-Damia🇪🇸 · Dionysios Anninos🇬🇧 · Tarek Anous🇬🇧 · Johnny Gleeson🇬🇧 · Alan Rios Fukelman🇬🇧

    We analyze a simple extension of the Schwinger model, which we refer to as the $p$-Schwinger model, on a de Sitter background. In this theory, the charged massless fermions carry non-unit integer charge $p$. In Minkowski space, the $p$-Schwinger model has discrete zero- and one-form global symmetries that are spontaneously broken, yielding $p$ degenerate ground states. We demonstrate that these features persist upon placing the $p$-Schwinger model on a global de Sitter background, establishing that such discrete global symmetries can be spontaneously broken for quantum field theories in de Sitter space. In particular, the theory is endowed with $p$ distinct, but locally-indistinguishable, de Sitter invariant states, the de Sitter vacua, satisfying the Hadamard property. We couple a variant of the $p$-Schwinger model with ${\mathrm{N}}_{\mathrm{f}}$ flavors to quantum gravity with $\Lambda >0$, and demonstrate the existence of a semiclassical de Sitter saddle at large ${\mathrm{N}}_{\mathrm{f}}$. In the gravitational theory, the $p$ de Sitter invariant vacua are speculatively interpreted as microstates of the de Sitter horizon in the low-energy effective field theory.

    ↳ hep-thcond-mat.str-elhep-ph3 citations
37. 37*

    Post-Recombination Fluctuations from a Sequestered Dark Sector

    Salvatore Bottaro🇮🇱 · Michael Geller🇮🇱 · Diego Redigolo🇮🇹 · Maya Tsur🇮🇱

    We develop a formalism to characterize the imprints of late-time sources of cosmological fluctuations under the sole assumption that the injection occurs on timescales short compared to the horizon. For post-recombination injections, we derive the general modification of photon geodesics in the presence of scalar, vector, and tensor perturbations, and compute the resulting impact on the Cosmic Microwave Background through the integrated Sachs-Wolfe effect. We show that the signal is generically dominated by instantaneous injections of anisotropic stress. As an application, we consider first-order phase transitions in a sequestered dark sector and show that current observations constrain fractional energy injections at the permille level.

    ↳ astro-ph.COhep-ph1 citation
38. 38*

    Beyond the Lorenz Gauge: Probing a Stueckelberg Scalar in the Electric Aharonov-Bohm Effect

    Renato Vieira dos Santos🇧🇷

    The electric Aharonov-Bohm effect -- a time-dependent scalar potential imparting a measurable phase shift on electrons in a region free of electromagnetic fields -- has never been experimentally tested in its original formulation with shielded, time-dependent potentials. This unexplored regime offers a rare opportunity: the Lorenz condition ${\partial }_{\mu }{A}^{\mu }=0$, a choice that eliminates a scalar degree of freedom from the electromagnetic potential, may not be the last word. If the Stueckelberg scalar $B={\partial }_{\mu }{A}^{\mu }$ survives as a physical field and couples to matter, it would produce a phase shift with a distinctive $1-\cos (\omega T)$ signature -- orthogonal to the standard $\sin (\omega T)$ and separable by a frequency sweep even if both contributions coexist. We propose a measurement protocol based on single-electron interferometry with picosecond time resolution, within reach of current technology. The experiment asks a question that has lingered since 1959: is the Lorenz gauge a matter of convenience, or a matter of principle?

    ↳ quant-phhep-ph0 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.