Thu·Jul 10, 2025Thursday·July 10, 2025

1. 01*

   Revisiting the Electron EDM in the NMSSM

   Kaifei Ning🇺🇸 · Michael Ramsey-Musolf🇨🇳

   The Next-to-Minimal Supersymmetric Standard Model (NMSSM) with explicit CP violation offers a promising framework for explaining the observed baryon asymmetry while remaining consistent with stringent electric dipole moment (EDM) bounds. In this work, we identify a previously overlooked set of two-loop diagrams that contribute to fermion EDMs in the NMSSM. Our analysis of the electron EDM shows that, for certain NMSSM specific CP-violating phases, these diagrams partially cancel existing contributions, thereby relaxing the associated constraints. In other phases, the diagrams dominate and tighten the bounds, which in turn necessitates more finely tuned parameters to reconcile successful baryogenesis with current EDM limits.

   hep-phhep-thPLB(2025)·5 citations
2. 02*

   Fresh look at the nuclear transparency using the generalized parton distributions

   The MMGPDs Collaboration · Muhammad Goharipour · Fatemeh Irani · K. Azizi · Dipangkar Dutta

   Color transparency (CT) is a fundamental phenomenon in QCD in which hadrons produced in high-energy exclusive processes traverse nuclear matter with minimal interactions. Nuclear transparency, which quantifies this attenuation suppression, is a quantity with high sensitivity to CT effects and provides critical insights into QCD dynamics in nuclear environments. In this study, we revisit nuclear transparency using the framework of generalized parton distributions (GPDs). By constructing nuclear GPDs (nGPDs) through the incorporation of nuclear parton distribution functions, we calculate the nuclear transparency $T(Q^2)$ for the carbon nucleus as a function of momentum transfer $Q^2$ considering various definitions and compare the results obtained with available experimental data. Our finding highlights the importance of choosing a physically motivated definition of nuclear transparency. Moreover, we emphasize that a more reliable determination of nGPDs requires a dedicated global analysis incorporating nuclear data. Such an approach is essential for improving the theoretical understanding of CT and for achieving consistency with experimental observations in the high-$Q^2$ regime.

   hep-phhep-exPRD(2025)·3 citations
3. 03*

   Grand-unification Theory Atlas: Standard Model and Beyond

   Giacomo Cacciapaglia🇫🇷 · Aldo Deandrea🇫🇷 · Konstantinos Kollias🇫🇷 · Francesco Sannino🇮🇹

   Under a reasonable set of ab-initio assumptions, we define and chart the atlas of simple gauge theories with families of fermions whose masses are forbidden by gauge invariance. We propose a compass to navigate the atlas based on counting degrees of freedom. When searching for Grand-unification Theories with three matter generations, the free energy singles out the SU(5) Georgi-Glashow model as the minimal one, closely followed by SO(10) with spinorial matter. The atlas also defines the dryland of grand-unifiable gauge extensions of the standard model. We further provide examples relevant for gauge dual completions of the standard model as well as extensions by an additional SU(N) gauge symmetry.

   hep-phhep-thPRD(2026)·6 citations
4. 04*

   Cherenkov radiation in isotropic chiral matter: the space-frequency domain

   R. Martínez von Dossow🇲🇽 · Eduardo Barredo-Alamilla🇷🇺 · Maxim A. Gorlach🇷🇺 · Luis F. Urrutia🇲🇽

   The electromagnetic response of isotropic chiral matter, as described by Carroll-Field-Jackiw electrodynamics, arises in distinct physical contexts ranging from condensed matter systems to Lorentz-violating extensions of high-energy physics. Here, we derive exact expressions for the circularly polarized electromagnetic fields that contribute independently to Cherenkov radiation in isotropic chiral matter. Each spectral energy distribution is gauge-invariant and positive, yielding radiation that emerges at a characteristic angle, akin to the standard case. Furthermore, we identify specific frequency ranges that permit zero, one, or two Cherenkov cones for a given setup. Remarkably, one sector of the model allows for the existence of threshold-free Cherenkov radiation arising from slowly-moving charges.

   hep-phcond-mat.mes-hallhep-thPLA(2025)·6 citations
5. 05*

   Experiments to test the hypothesis for solar and dark matter axions

   Babette Döbrich🇩🇪 · Igor G. Irastorza🇪🇸

   We present a pedagogical introduction to the direct search of axions as dark matter, as well as to searches for solar axions. The plethora of experimental searches exploit the axion's coupling to two photons: They attempt to convert the axion dark matter to photons in a resonator placed in an external magnetic field or convert solar axions into X-rays in a magnet pointing towards the sun. We give a basic introduction to this concept, its many variants and to searches that exploit the axion's other couplings. We also speculate about potentially transformative developments for such searches in the near-term future.

   hep-phhep-ex6 citations
6. 06*

   Dark Walker in the Early Universe: A Strongly Coupled Sector Model

   Chen Yang🇮🇹

   We explore the phenomenology of the ``Dark Walker'' -- an $\text{SU}(3)$ theory with eight flavors of massless fundamental fermions in the dark sector. During inflation, its walking dynamics generate primordial non-Gaussianities through the exchange of unparticles, while accounting for the current dark matter relic abundance if we consider freeze-in of Dark Walker coupled to the Standard Model through the Higgs portal. This provides a simple yet predictive example linking strongly coupled inflationary dynamics to present-day dark matter.

   hep-phastro-ph.COhep-thPLB(2026)·6 citations
7. 07*

   Chiral symmetry breaking and pion condensation in the early universe

   Osvaldo Ferreira🇧🇷 · Eduardo S. Fraga🇧🇷 · Maurício Hippert🇧🇷 · Jürgen Schaffner-Bielich🇩🇪

   We determine the possible trajectories the universe may have followed in the QCD phase diagram during the QCD epoch. We focus on the roles of chiral symmetry breaking and pion condensation under high imbalances in lepton asymmetry. Adopting the quark-meson model as an effective description of QCD at finite temperature, charge and baryon chemical potentials we show that, for sufficiently large but physically motivated asymmetries, the universe may have entered the pion condensation phase through a first-order phase transition, followed by a second-order phase transition when exiting it. Such a first-order phase transition represents a new possible source of primordial gravitational waves during the QCD epoch.

   hep-phnucl-thPRD(2025)·11 citations
8. 08*

   Electroweak splitting functions in the Standard Model and beyond

   Stefan Dittmaier🇩🇪 · Max Reyer🇩🇪

   We derive quasi-collinear factorization formulas in generic spontaneously broken gauge theories with scalars, fermions, and vector bosons. Specifically, we obtain polarized leading-order splitting functions for all possible final-state and initial-state 1->2 processes in the considered gauge theory. The main complication lies in the presence of mass-singular terms in longitudinal polarization vectors, prohibiting the direct application of the usual factorization procedure known from Quantum Electrodynamics and Quantum Chromodynamics. We overcome this issue with two different strategies, using gauge invariance and Ward identities as guiding principle. Our derivations do not use any explicit component-wise parametrizations of momenta and wave functions and bear no reference to a particular Lorentz frame. Furthermore, our results are valid for completely general definitions of the spin reference axes of the individual external particles. The various massless limits, the special case of the Electroweak Standard Model, the reproduction of existing literature results, and symmetry relations among our splitting functions are discussed in detail.

   hep-phJHEP(2026)·10 citations
9. 09*

   Resonant leptogenesis in inverse see-saw framework with modular $S_4$ symmetry

   Abhishek🇮🇳 · V. Suryanarayana Mummidi🇮🇳

   We introduce a lepton mass generation and flavor mixing model, realized through a (2,3) inverse seesaw structure based on modular \( S_4 \) symmetry. The model employs modular forms to construct the lepton Yukawa couplings, significantly simplifying the framework by reducing redundant parameters. A detailed numerical analysis demonstrates consistency with current neutrino oscillation data, yielding specific outputs for the mixing angles and CP-violating phases. The Dirac CP phase is predicted to lie near ${\delta }_{\mathrm{CP}}\approx \pm 90^{\circ }$, corresponding to near-maximal leptonic CP violation. The total neutrino mass lies within $\sum m_{\nu }\approx 0.0587\text{–}0.0924$ eV, and the effective Majorana mass $|m_{ee}|\approx (0.002\text{–}0.02)$ eV, within reach of upcoming neutrinoless double beta decay experiments such as nEXO and AMoRE-II. The model also remains consistent with current bounds on charged lepton flavor violating processes from MEG and BaBar. We further explore resonant leptogenesis enabled by quasi-degenerate heavy neutrino states and show that the observed baryon asymmetry of the universe can be successfully generated in this scenario. The combined treatment of low-energy observables and high-scale baryogenesis demonstrates the predictivity and testability of the modular \( S_4 \)-based ISS(2,3) framework.

   hep-phEPJC(2026)·4 citations
10. 10*

    Understanding the low-lying ${\Omega }_c$ structures from a coupled-channel perspective

    Ying Zhang🇨🇳 · Qing-Fu Song🇨🇳 · Qi-Fang Lü🇨🇳 · Hideko Nagahiro🇯🇵 · Atsushi Hosaka🇯🇵

    We perform a systematic analysis of the low-lying ${\Omega }_c$ structures in a coupled-channel approach. The couplings between meson-baryon channels, ${\Xi }_c\bar{K}$, ${\Xi }_c^{\prime }\bar{K}$, ${\Xi }_c^{\ast }\bar{K}$, ${\Omega }_c\eta$ and ${\Omega }_c^{\ast }\eta$, and three-quark bare states ${\Omega }_c(1P_{\lambda })$ are considered. We predict a bound state ${\Omega }_c(2954)$ below the ${\Xi }_c\bar{K}$ threshold with $(J^P,j)=(1/2^{-},0)$, which can be studied in the final states of ${\Omega }_c^{(\ast )}\pi$ and ${\Omega }_c^{(\ast )}\gamma$. Also, the resonances ${\Omega }_c(3000)$ and ${\Omega }_c(3050)$ can be classified as the lower $(J^P,j)=(1/2^{-},1)$ and $(J^P,j)=(3/2^{-},1)$ states, respectively. Our present assignments based on this coupled-channel perspective are significantly different from those of traditional three-quark picture and of molecular scenario. The future BelleII and LHCb experiments can search for the bound state ${\Omega }_c(2954)$ and measure the spin-parities of particles ${\Omega }_c(3000)$ and ${\Omega }_c(3050)$ to test our predictions.

    hep-phhep-exPRD(2025)·3 citations
11. 11*

    Two-flavor color superconductivity in a general Nambu-Jona-Lasinio model with color and charge neutrality

    Li-Kang Yang🇨🇳 · Di-Sheng Fan🇨🇳 · Cheng-Ming Li🇨🇳 · Yong-Liang Ma🇨🇳

    By using a general NJL model including as many interaction channels as possible, and taking into account the constraints imposed by color and charge neutrality, we analyze how the different interaction channels contribute to the charge-neutral two-flavor color-superconducting matter. After taking the Fierz transformation, the number of parameters in the NJL model is reduced and thereby quark-antiquark condensates and diquark condensates are related. Through a self-consistent solution of the gap equations, we find that in addition to the diquark and vector channels, the scalar-isovector, vector-isovector, and vector-isovector-color-octet channels are also important, while other channels can be neglected. Moreover, between the normal quark matter phase and two-flavor color-superconducting phase, there is a gapless two-flavor color-superconducting phase. The fractions of quarks with different flavors and colors are calculated in both gaped and gapless two-flavor color-superconducting phases. In addition, We illustrate the phase diagrams in the diquark coupling and chemical potential plane, and discuss in detail how the dominant channels influence these phase diagrams.

    hep-phnucl-thPRD(2025)·8 citations
12. 12*

    Structure of the ${\Omega }^{-}(2012)$ with Hamiltonian Effective Field Theory

    Fang-Chao Han🇨🇳 · Zhan-Wei Liu🇨🇳 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺

    We investigate the internal structure of the $\Omega (2012{)}^{-}$ by analyzing lattice QCD simulation and experimental data within Hamiltonian effective field theory, considering both $J^P=1/2^{-}$ and $3/2^{-}$ assignments. The couplings to the dominant decay channel $\Xi \bar{K}$ and the near-threshold channel $\Xi (1530)\bar{K}$ are determined through the quark-pair-creation model. By studying the lattice QCD spectra in these two spin-parity scenarios, we extract the masses and widths of the resonances. We notice that the $J^P=3/2^{-}$ resonance is consistent with the observed $\Omega (2012{)}^{-}$ while the recently reported $\Omega (2109{)}^{-}$ may be a $J^P=1/2^{-}$ $\Omega$.

    hep-phhep-exhep-latPRD(2025)·14 citations
13. 13*

    Dark monopoles

    Vicente Vento🇪🇸

    Monopoles have been a subject of much theoretical and experimental research since they were proposed to symmetrize Maxwell's equations. However, no experimental signature of their existence has been detected. Many mechanisms have been proposed to explain this lack of success. In here we generalize QED to a two photon theory where the extraordinary photon and the monopole belong to the dark sector, and the ordinary photon and the electron to the non-dark sector. A mixing interaction transforms both electron and monopole into dyons generating experimental consequences for indirect and direct monopole detection which we analyze.

    hep-phhep-exhep-th2 citations
14. 14*

    Data-Driven Einstein-Dilaton Model for Pure Yang-Mills Thermodynamics and Glueball Spectrum

    Xun Chen🇨🇳 · Yidian Chen🇨🇳 · Kai Zhou🇨🇳

    We develop a machine learning assisted holographic model that consistently describes both the equation of state and glueball spectrum of pure Yang-Mills theory, achieved through neural network reconstruction of Einstein-dilaton gravity. Our framework incorporates key non-perturbative constraints of lattice QCD data: the ground ($0^{++}$) and first-excited ($0^{++\ast }$) scalar glueball masses pins down the infrared (IR) geometry, while entropy density data anchors the ultraviolet (UV) behavior of the metric. A multi-stage neural network optimization then yields the full gravitational dual -- warp factor $A(z)$ and dilaton field $\Phi (z)$ -- that satisfies both spectroscopic and thermodynamic constraints. The resulting model accurately reproduces the deconfinement phase transition thermodynamics (pressure, energy density, trace anomaly) and predicts higher glueball excitations ($0^{++\ast \ast }$, $0^{++\ast \ast \ast }$) consistent with available lattice calculations. This work establishes a new paradigm for data-driven holographic reconstruction, solving the long-standing challenge of unified description of confinement thermodynamics and spectroscopy.

    hep-phPRD(2025)·10 citations
15. 15*

    A realistic photon spectra in polarized {\gamma}{\gamma} processes in SANCphot

    Sergey G. Bondarenko🇷🇺 · Aidos Issadykov🇷🇺 · Lidia V. Kalinovskaya🇷🇺 · Andrey A. Sapronov🇷🇺

    This work presents an approach to improve the precision of polarized photon-photon collisions simulation implemented in the SANCphot package. The basic linear Compton approximation of the incoming photon spectrum is extended to a general energy distribution and a realistic description of circular or linear polarizations as expected to be seen at photon-photon colliders.

    hep-phEPJC(2025)·0 citations
16. 16*

    A model for baryon production in spin-dependent string fragmentation

    Albi Kerbizi🇮🇹 · Xavier Artru🇫🇷

    We introduce spin-1/2 baryons in the string+${}^3{P}_0$ model of hadronization, previously restricted to the production of pseudoscalar and vector mesons. Baryons are modeled as quark-diquark bound states and baryon production is described by the tunneling of diquark-antidiquark pairs at string breaking points. Diquarks can be scalar or pseudovector, the latter being produced in the relative ${}^5{D}_0$ state. Introducing the quark-baryon-diquark coupling, the relevant splitting amplitudes for the emission of baryons are constructed and used to explore analytically the model predictions. We find a Collins effect for baryon production in the fragmentations of transversely polarized quarks or diquarks as well as a baryon spontaneous transverse polarization. The hadronic decays of polarized hyperons are also included in the model, which is presented in a form suitable for the implementation in a Monte Carlo event generator.

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

    From topological amplitudes to rescattering dynamics in charmed baryon decays

    Ying-Xin Lai🇨🇳 · Di Wang🇨🇳

    Charmed baryon decays play an important role in studying the weak and strong interactions, which have been studied in the rescattering dynamics and topological diagram approach. In this work, we establish a theoretical framework to correlate the topological diagram at quark level and rescattering dynamics at hadron level. Note that the chiral Lagrangian involving octet baryons is constructed via (1,1)-rank octet tensors, while topological diagrams are constructed by 3-rank octet tensors. We propose that, the (1,1)-rank amplitudes, which are linear combinations of topological diagrams, will be a bridge between topological amplitudes and rescattering dynamics. The possible meson-meson or meson-baryon coupling configurations are constructed via tensor contractions. The rescattering amplitudes derived from topological amplitudes are consistent with those derived directly from the chiral Lagrangian. The $u$-, $t$-, and $s$-channel rescattering amplitudes contributing to each (1,1)-rank amplitudes in the $SU(3{)}_F$ limit are derived. Isospin sum rules for all isospin systems in $B_{c\overline{3}}\to B_{8}P$ decays are checked in terms of rescattering amplitudes. The rescattering amplitudes contributing to penguin diagrams are found to be comparable to those contributing to tree diagrams, indicating potential observable $CP$ violation in charmed baryon decays. Furthermore, it is found that the Körner-Pati-Woo theorem is not consistent with the rescattering dynamics. The proof of the Körner-Pati-Woo theorem is questionable when the color changes of quarks arising from gluons are considered. We suggest precisely measuring the branching fraction of the ${\Lambda }_c^{+}\to {\Sigma }^{+}{K}_S^0$ mode on Belle (II) to test the Körner-Pati-Woo theorem.

    hep-ph4 citations
18. 18*

    Inverse Seesaw Model in Non-holomorphic Modular $A_4$ Flavor Symmetry

    Xianshuo Zhang🇨🇳 · Yakefu Reyimuaji🇨🇳

    This paper investigates an inverse seesaw model of neutrino masses based on non-holomorphic modular $A_4$ symmetry, extending the framework of modular-invariant flavor models beyond the conventional holomorphic paradigm. After the general theoretical framework is established, three concrete model realizations distinguished by their $A_4$ representation assignments and modular weight configurations for the matter fields are analyzed. Focusing on these three specific realizations, a comprehensive analysis of neutrino phenomenology is performed. By constraining the modulus parameter $\tau$ to the fundamental domain and systematically scanning the parameter space, regions compatible with current neutrino oscillation data are identified. The numerical results provide predictions for currently unmeasured quantities, including the absolute neutrino mass scale, Dirac CP-violating phase, and Majorana phases. These predictions establish specific, testable signatures for upcoming neutrino experiments, particularly in neutrinoless double beta decay and precision oscillation measurements. The framework offers a well-defined target for future experimental verification or exclusion, while demonstrating the phenomenological viability of non-holomorphic modular symmetry approaches to flavor structure.

    hep-phPRD(2025)·15 citations
19. 19*

    Hidden-Heavy Pentaquarks and Where to Find Them

    Fareed Alasiri🇺🇸 · Eric Braaten🇺🇸 · Roberto Bruschini🇺🇸

    We provide a simple explanation for the observed hidden-charm pentaquarks as bound states in Born-Oppenheimer potentials. We identify $P_{c\bar{c}}(4312{)}^{+}$, $P_{c\bar{c}}(4440{)}^{+}$, and $P_{c\bar{c}}(4457{)}^{+}$ as heavy-quark spin states in a quartet of $c\bar{c}$ pentaquarks with $J^P$ quantum numbers ${\frac{1}{2}}^{-}$, ${\frac{3}{2}}^{-}$, and ${\frac{5}{2}}^{-}$. The quantum numbers of $P_{c\bar{c}}(4457{)}^{+}$ differ from most previous predictions. We also predict a fourth $c\bar{c}$ pentaquark with quantum numbers ${\frac{3}{2}}^{-}$ near the ${\Sigma }_c^{\ast }\bar{D}$ threshold. We identify $P_{c\bar{c}s}(4338{)}^0$ and $P_{c\bar{c}s}(4459{)}^0$ as heavy-quark spin states in a triplet of $c\bar{c}s$ pentaquarks with quantum numbers ${\frac{1}{2}}^{-}$ and either ${\frac{1}{2}}^{-}$ or ${\frac{3}{2}}^{-}$. We also predict a third $c\bar{c}s$ pentaquark with quantum numbers either ${\frac{3}{2}}^{-}$ or ${\frac{1}{2}}^{-}$ near the ${\Xi }_c{\bar{D}}^{\ast }$ threshold. We explain why the observed hidden-charm pentaquarks have narrow widths.

    hep-phPLB(2026)·8 citations
20. 20*

    Cosmological phase transitions without high-temperature expansions

    Pablo Navarrete🇫🇮 · Risto Paatelainen🇫🇮 · Kaapo Seppänen🇫🇮 · Tuomas V. I. Tenkanen🇫🇮

    We introduce a new framework for perturbatively computing equilibrium thermodynamic properties of cosmological phase transitions to high loop orders, using the full four-dimensional resummed thermal effective potential and avoiding the limitations of standard high-temperature approximations. By systematically disentangling the physics of hard and soft momentum scales, our approach unifies their treatment within a single expression, enabling consistent handling of both vacuum and thermal divergences across all mass regimes. This core innovation enables the efficient numerical evaluation of massive multiloop thermal sum-integrals, achieved through a finite-temperature generalization of Loop-Tree Duality -- an advanced algorithmic technique originally developed to render vacuum Feynman integrals numerically tractable via Monte Carlo methods. As a proof of principle, we apply the framework to a scalar-Yukawa model, presenting a complete two-loop calculation and a novel three-loop extension -- the first fully massive three-loop sum-integral computation without relying on high-temperature expansions. Our approach opens the door to precise perturbative predictions of the phase structure in a broad class of beyond-the-Standard-Model scenarios, including those featuring strong first-order phase transitions relevant for gravitational-wave signals, where conventional high-temperature approximations break down.

    hep-phJHEP(2026)·23 citations
21. 21*

    Resolving the QCD Axion Domain Wall Problem with a Light Axion

    Junseok Lee🇯🇵 · Kai Murai🇯🇵 · Fuminobu Takahashi🇯🇵 · Wen Yin🇯🇵

    We propose two novel solutions to the domain wall problem of the QCD axion by introducing a massless or light axion that also couples to gluons. The first solution applies when the new axion forms strings after inflation. Due to its mixing with the QCD axion, domain walls of the QCD axion are bounded by these strings and confined into cosmologically safe string bundles. This scenario predicts the existence of such string bundles, which may survive until today and leave observable signatures, such as gravitational waves, cosmic birefringence, and CMB anisotropies. The simultaneous detection of the QCD axion and any of these cosmological signatures would serve as a smoking-gun signal. The second solution assumes a homogeneous initial condition for the new axion. If it is sufficiently light, its potential temporarily induces a bias in the QCD axion potential before the onset of oscillations, rendering the domain walls unstable. In both scenarios, the Peccei-Quinn mechanism remains effective, and the strong CP problem is not reintroduced. We identify the viable parameter regions and discuss the resulting dark matter abundance.

    hep-phastro-ph.COJHEP(2026)·12 citations
22. 22*

    Testing frozen-in pNGB dark matter with a long-lived dark Higgs

    Nicolás Bernal🇦🇪 · Giovanna Cottin🇨🇱 · Bastián Díaz Sáez🇨🇱 · Manuel López🇨🇱

    We consider a simple Higgs portal dark matter (DM) model, where the Standard Model is extended with a complex singlet scalar. The imaginary part of the scalar becomes a massive and stable pseudo-Nambu-Goldstone boson, serving as the DM candidate, while the real part gives rise to a second (dark) Higgs boson. We focus on the freeze-in production of the DM, paying particular attention to low-reheating temperature scenarios, where the dark Higgs can be a long-lived particle (LLP). We also explore the phenomenology of this dark Higgs at the LHC and the Future Circular Collider in hadron-hadron mode, discussing its discovery prospects in regions of parameter space consistent with current DM constraints. Our results emphasize the impact of the cosmic reheating dynamics on the DM freeze-in production and their critical role in interpreting collider signatures. Furthermore, our findings suggest that LLP searches may provide insights into the fundamental dynamics of reheating.

    hep-phhep-exJHEP(2026)·13 citations
23. 23*

    Unconventional Materials for Light Dark Matter Detection

    Yonit Hochberg🇮🇱 · Dino Novko🇭🇷 · Rotem Ovadia🇮🇱 · Antonio Politano🇮🇹

    We propose the use of several unconventional materials as detectors for dark matter with mass beneath the MeV scale. These include the transition-metal dichalcogenide TiSe${}_2$ hosting a low-energy plasmon in the charge-density-wave phase, Sr${}_2$RuO${}_4$ containing a low-energy acoustic demon mode, and hole-doped diamond with tunable optical and acoustic plasmon frequencies. We perform first-principles density functional theory computations of their loss functions at non-vanishing momenta and establish their reach into light dark matter parameter space. We show that due to intense low-energy plasmon modes -- of different microscopic origin in each -- the reach of detectors based on these materials could surpass existing proposals by several orders of magnitude for both dark matter scattering and absorption on electrons. The anisotropic response of these materials, which enables directional detection, renders them exceptionally strong detector candidates, motivating the design and fabrication of future devices.

    hep-phcond-mat.mtrl-scihep-exphysics.ins-detPRL(2026)·8 citations
24. 24*

    Polarized Deep Inelastic Scattering as $x\to 1$ using Soft Collinear Effective Theory

    Jaipratap Singh Grewal🇺🇸 · Aneesh V. Manohar🇺🇸 · Jyotirmoy Roy🇺🇸

    We use Soft Collinear Effective Theory (SCET) to factorize the polarized Deep Inelastic Scattering (DIS) structure functions $g_1(x)$ and $g_2(x)$, and to sum Sudakov double logarithms of $1-x$. The analysis is done both in terms of lightcone parton distributions and their moments. Computing $g_2$ requires subleading SCET operators which contain gluons. We calculate the one-loop matching coefficients from QCD onto these subleading SCET operators, and the one-loop matching from SCET onto the parton distribution function (PDF). The PDF in SCET is given by a bilocal operator, rather than the trilocal operator used in the QCD analysis of $g_2$ for generic $x$. We compute the one-loop anomalous dimension of the PDF operator for any $x$, and show that as $x\to 1$, it factors into a single-variable evolution. We comment on the QCD anomalous dimensions of twist-three operators, their equation-of-motion relation, and connection to the SCET analysis. We briefly discuss the definition of axial operators in the BMHV scheme. As a side result, we derive the $1/N$ dependence of the QCD coefficient functions for $F_1$, $F_L$ and $g_1$ in the $N\to \infty$ limit, where $N$ is the moment, which is expected to hold to all orders in ${\alpha }_s$.

    hep-phJHEP(2026)·0 citations
25. 25*

    Amplifying muon-to-positron conversion in nuclei with ultralight dark matter

    Purushottam Sahu🇮🇳 · Manibrata Sen🇮🇳

    We present an analysis of the lepton-number and lepton-flavour-violating process of muon-to-positron conversion ${\mu }^{-}+N\to e^{+}+N^{\prime }$, in the presence of an ultralight scalar dark matter (ULSDM) field which couples to neutrinos. The ULSDM contributes to the effective off-diagonal Majorana mass $m_{\mu e}$, therefore amplifying the rate of muon-to-positron conversion to experimentally observable levels. Using existing bounds from SINDRUM II, COMET, and Mu2e experiments, we derive novel constraints on the flavour-off-diagonal couplings of neutrinos to ULSDM. Our work reveals that upcoming experiments can provide stronger sensitivity to these new couplings than bounds arising from cosmological surveys and terrestrial experiments.

    hep-phnucl-thJ.Phys.G(2026)·1 citation
26. 26*

    Exploring Quantum Statistics for Dirac and Majorana Neutrinos using Spinor-Helicity techniques

    Innes Bigaran🇺🇸 · Stephen J. Parke🇺🇸 · Pedro Pasquini🇧🇷

    Recently, there has been interest in the applicability of quantum statistics to distinguish Dirac from Majorana neutrinos in multi-neutrino final states. In particular, debate has arisen over the validity of the Dirac-Majorana confusion theorem in these processes, i.e. that any distinction between the Dirac and Majorana processes goes to zero as the neutrino mass goes to zero. Here we approach this problem equipped with spinor-helicity methods generalized for massive Dirac and Majorana fermions. We explicitly calculate all helicity amplitudes for the decay of a light scalar particle to two neutrinos and two oppositely charged leptons. This allows us to pinpoint the crucial steps which could lead to claims of a violation of the confusion theorem. We show that if the correct anti-symmetrization of Dirac to Majorana amplitudes is used, identification of which is clear in this framework, and all relevant contributions are appropriately summed, a scalar decay into two charged leptons and two neutrinos satisfies the Dirac-Majorana confusion theorem.

    hep-phhep-exhep-thPRD(2025)·3 citations
27. 27*

    Asymptotic behavior of the Speed of Sound in Dense Matter

    Udita Shukla🇵🇱 · Pok Man Lo🇵🇱

    We show that a class of NJL-like models fails to reproduce the expected conformal limit of the speed of sound, making them unsuitable for analyzing the equation of state of dense matter. We then demonstrate how this issue can be resolved within a simple dynamical quark model.

    ↳ nucl-thastro-ph.HEhep-phActa Phys.Polon.Supp.(2025)·3 citations
28. 28*

    Effects of Lorentz invariance violation on charged particles and photon production in astrophysical sources

    Matheus Duarte🇧🇷 · Vitor de Souza🇧🇷

    We investigate the impact of Lorentz invariance violation (LIV) on radiation processes in astrophysical sources, focusing on synchrotron and inverse Compton interactions. We derive modified expressions for radiated power and photon energy under LIV assumptions and incorporate them into first-order Fermi acceleration models. Our analysis reveals energy thresholds beyond which LIV, within a kinematic framework, significantly alters particle dynamics and photon spectra, introducing non-physical divergences that highlight limitations in perturbative approaches. We model synchrotron self-Compton (SSC) emission in the presence of LIV and assess its consequences for photon fluxes from blazars, including Markarian 501 and the BL Lac population. LIV introduces distinct high-energy emission regions that deviate from standard expectations. Comparisons with observational data, particularly upper limits from the Pierre Auger Observatory, suggest that future multi-messenger observations, together with the full analysis of particle's trajectories, could constrain LIV parameters through the non-detection of such excesses.

    ↳ astro-ph.HEhep-phJCAP(2026)·1 citation
29. 29*

    Cosmic baryon census with fast radio bursts and gravitational waves

    Ji-Guo Zhang🇺🇸 · Ji-Yu Song🇺🇸 · Wan-Peng Sun🇺🇸 · Ze-Wei Zhao🇺🇸 · Jing-Fei Zhang🇺🇸 · Xin Zhang🇺🇸

    The cosmic baryon density fraction (${\Omega }_{\mathrm{b}}$) is intrinsically correlated with the Hubble constant ($H_0$) through the critical density of the Universe. In the context of the decade-long $H_0$ tension, the significant discrepancy between early- and late-Universe measurements of $H_0$ implies that fixing its value or imposing an external prior could bias the baryon census. To address this concern, we construct a late-Universe probe framework that unifies fast radio bursts (FRBs) and gravitational-wave (GW) standard sirens, which can respectively resolve the ''missing baryon'' problem and the $H_0$ tension through their dispersion measures (DMs) and absolute luminosity distances. By combining $104$ localized FRBs with $47$ GW events, we obtain an $H_0$-free measurement of ${\Omega }_{\mathrm{b}}=0.0488\pm 0.0064$ ($1\sigma$), in concordance with early-Universe observations of CMB + BBN. The result is tightly anchored by GW-inferred $H_0$ through the strong ${\Omega }_{\mathrm{b}}$-$H_0$ degeneracy. Although the current precision ($\sim 13\%$) is limited by sample size, the growing detections of both FRBs and GWs will make their synergy a powerful probe of low-redshift cosmology.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ph20 citations
30. 30*

    Transition from weak to strong coupling in thermal gauge theories: Lessons from $\mathcal{N}=4$ SYM Theory

    Berndt Müller🇺🇸

    We investigate the transition between weak and strong coupling in thermal $\mathcal{N}=4$ supersymmetric Yang-Mills (SYM) theory as a function of 't Hooft coupling $\lambda$ for several quantities of phenomenological interest for which next-to-leading order calculations are available in both regimes. We use Padé approximants to interpolate between the weak and strong coupling expansions and determine the location and width of the transition between the asymptotic regimes.

    ↳ hep-thhep-phnucl-thPRD(2025)·4 citations
31. 31*

    The QED photon-fermion vertex from its Dyson-Schwinger equation in 4D: the full vertex, the transverse form factors and the perturbative solution

    Orlando Oliveira🇵🇹

    We investigate the Dyson-Schwinger equation for the photon-fermion one-particle irreducible vertex in QED in linear covariant gauges. The longitudinal component of this vertex is described using the Ball-Chiu basis, while its transverse part is expressed with the Kızılersu-Reenders-Pennington basis. Combining the vertex Ward-Takahashi identity with the vertex equation, we derive a set of exact, non-linear integral equations governing the transverse vertex. These equations hold for any linear covariant gauge and must be solved self-consistently. We discuss several approximations to the exact equations, generalizing results previously obtained at the perturbative one-loop level. Various kinematical configurations are also examined. Furthermore, we compute the perturbative solution of the transverse vertex Dyson-Schwinger equations for all transverse form factors and derive their perturbative asymptotic expressions.

    ↳ hep-thhep-phPRD(2025)·1 citation
32. 32*

    Little Red Dots from Small-Scale Primordial Black Hole Clustering

    Borui Zhang🇨🇳 · Wei-Xiang Feng🇨🇳 · Haipeng An🇨🇳

    The James Webb Space Telescope (JWST) observations have identified a class of compact galaxies at high redshifts ($4\lesssim z\lesssim 11$), dubbed "little red dots" (LRDs). The supermassive black holes (SMBHs) of $10^{5-8}{\mathrm{M}}_{\odot }$ in LRDs favor a heavy-seed origin. We propose a mechanism for their formation: Clusters of primordial black holes, formed through long-short mode coupling on small scales in the early Universe, undergo sequential mergers over extended timescales. This mechanism can evade cosmic microwave background distortions and result in heavy-seed SMBHs via runaway mergers. We employ Monte Carlo simulations to solve the Smoluchowski coagulation equation and determine the runaway merging timescale. The resulting stochastic gravitational wave background offers a distinct signature of this process, and the forming SMBHs can be highly spinning at their formation due to the spin residual of the cluster from tidal fields. This mechanism may explain the rapidly spinning SMBHs in LRDs under the assumption of obscured active galactic nuclei.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph17 citations
33. 33*

    A Prototype Hybrid Mode Cavity for Heterodyne Axion Detection

    Zenghai Li🇺🇸 · Kevin Zhou🇺🇸 · Marco Oriunno🇺🇸 · Asher Berlin🇺🇸 · Sergio Calatroni🇨🇭 · Raffaele Tito D'Agnolo🇫🇷 · Sebastian A. R. Ellis🇨🇭 · Philip Schuster🇺🇸 · Sami G. Tantawi🇺🇸 · Natalia Toro🇺🇸

    In the heterodyne approach to axion detection, axion dark matter induces transitions between two modes of a microwave cavity, resulting in a parametrically enhanced signal power. We describe the fabrication and characterization of a prototype normal conducting cavity specifically optimized for heterodyne detection. Corrugations on the cavity walls support linearly polarized hybrid modes which maximize the signal power while strongly suppressing noise. We demonstrate tuning mechanisms which allow one mode's frequency to be scanned across a 4 MHz range, while suppressing cross-coupling noise by at least 80 dB. A future superconducting cavity with identical geometry to our prototype would have the potential to probe orders of magnitude beyond astrophysical bounds.

    ↳ physics.ins-dethep-exhep-phNucl.Instrum.Meth.A(2026)·8 citations
34. 34*

    Women in STEM: Interview with Halina Abramowicz

    Elisabetta Gallo🇩🇪 · Henriette Ullmann

    This short article is a first of a series describing the scientific journey of exceptional women scientists in experimental particle physics. We interviewed Halina Abramowicz, who started her career in hadron-hadron interactions, in neutrino physics, became an expert of strong interactions, guided the European Particle Physics Strategy Update in 2020 and now moved to an experiment in strong-field QED.

    ↳ physics.soc-phhep-exhep-phnucl-ex0 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.