Mon·May 4, 2026Monday·May 4, 2026

1. 01*

   Crossing into the $m_a>f_a$ Region for Leptophilic ALPs

   Marta F. Zamoro🇪🇸 · Álvaro Lozano-Onrubia🇪🇸 · Luca Merlo🇪🇸 · Samuel Rosende Herrero🇪🇸

   Axion-like particles (ALPs) are typically identified as pseudoscalars whose couplings are shift-symmetry invariant with the exception of their couplings to gauge bosons and their mass term. Additionally, the ALP mass $m_a$ is usually assumed to be (much) smaller than the ALP decay constant $f_a$. The latter condition is conservative, at best, and excludes part of the ALP parameter space that is presently viable. We revisit the criterion of the $m_a\ll f_a$ and perform an analysis focussing on leptophilic ALPs. In particular, we explore regions of the parameter space still uninvestigated, where $m_a>f_a$, thus providing a phenomenological study of the ALP-lepton couplings complementary to the existing literature. We point out that a leptophilic ALP may explain the $-3.8\sigma$ tension in the anomalous magnetic dipole moment of the electron for the Caesium determination in a large region of the $m_a\times f_a$ parameter space, testable in the near future through studies on $\mu \to e$ conversion in nuclei.

   hep-ph3 citations
2. 02*

   Reciprocal symmetry and KNO scaling violation in proton-proton collisions

   Mustapha Ouchen🇮🇱 · Alex Prygarin🇮🇱

   We analyze the charged particle multiplicity distributions in $p-p$ collisions and discuss the violation of the Koba--Nielsen--Olesen (KNO) scaling. We extract the deviations from the leading exponential behavior of the KNO scaled probability and identify a reciprocal symmetry $z\leftrightarrow 1/z$ in the KNO violating corrections observed in the ATLAS and CMS data at $\sqrt{s}=7,8,13$~TeV. The symmetry imposes a local constraint on the multiplicity distribution at $n=⟨n⟩$, namely $P^{\prime }(⟨n⟩)=-P(⟨n⟩)/⟨n⟩$, which we verify directly in the data. We use this constraint to extract the entanglement entropy from the well-measured region $n\simeq ⟨n⟩$, avoiding the large uncertainties associated with the distribution tail.

   hep-phhep-thPRD(2026)·2 citations
3. 03*

   Extracting production fractions of $b$ hadrons from exclusive semi-leptonic decays

   Carolina Bolognani🇩🇪 · Martin Jung🇮🇹 · Méril Reboud🇫🇷 · K. Keri Vos🇳🇱

   Ratios of production fractions of $b$ hadrons are a dominant source of uncertainty in many LHC analyses, in particular in measurements with $B_s$ mesons. The currently used value for $f_s/f_d$ is based on a combination of hadronic and semi-inclusive semi-leptonic decays, and relies in part on assumptions about the underlying decays that are hard to quantify. We propose an independent alternative method to obtain this quantity by measuring ratios of the exclusive semi-leptonic decays ${\bar{B}}_{(s)}\to D_{(s)}^{(\ast )}\ell \bar{\nu }$. This method benefits from significant cancellations of both experimental and theoretical uncertainties, as well as robustness against potential contamination from heavy physics beyond the Standard Model. As a proof of principle, we show that current measurements constrain $f_s/f_d$ with an uncertainty of $7\%$, dominated by present experimental uncertainties. This method can also be applied to other ratios of production fractions involving heavier $b$ hadrons, such as $B_c$ or ${\Lambda }_b$.

   hep-ph1 citation
4. 04*

   Micron-sized Extra Dimensions and Primordial Black Holes: Charged, Rotating, and Memory Burdened

   George K. Leontaris🇬🇷 · George Prampromis🇬🇷

   We explore the possibility of explaining dark matter through six-dimensional (6D) primordial black holes (PBHs) in a theory with two extra dimensions. Interestingly, in this scenario the fundamental energy scale is of the order of $\sim 10$ TeV, accessible by future experiments. We analyse the viability of charged and rotating 6D black holes under standard Hawking evaporation as well as the memory burden scenario. In the case of pure Hawking evaporation, only PBHs with masses $M>10^8$ g survive to present, while the lifetime of near-extremal configurations is extended by a factor $1/{\beta }^{1/2}$, where the parameter $\beta$ characterizes small deviations from extremality. In the memory burden scenario evaporation is enormously suppressed, and sub-gram mass PBHs can survive to the present epoch. At future colliders such as the Future Circular Collider, these micro black holes produce characteristic high multiplicity events, $⟨N⟩\sim 21$, with thermal spectra, enabling direct probes of the fundamental scale and the number of extra dimensions. We find that the memory burden mechanism opens a broad new mass window for light PBH dark matter, while the Kaluza-Klein mass splitting $\Delta m$ aligns with the atmospheric neutrino scale, $\sqrt{\Delta m_{\text{atm}}^2}$ suggesting a unified framework between Swampland constraints, cosmology, collider physics, and low energy phenomenology.

   hep-phgr-qchep-exhep-th5 citations
5. 05*

   Evidence for Quark Confinement in the Proton

   Xiangdong Ji🇺🇸 · Gerald A. Miller🇺🇸 · Chen Yang🇺🇸

   The strong interaction is the fundamental force that holds quarks and the gluon force carriers together to form protons and neutrons and also binds the atomic nucleus. The theory governing quark-gluon interactions is Quantum Chromodynamics (QCD). A wide variety of experimental data teaches us that quarks and gluons cannot be observed in isolation, a phenomenon known as confinement that is unique to QCD. But no one has used QCD to mathematically prove confinement. Here we show how to define and measure the force on quarks in the proton using available experimental data. Direct evidence for confinement is obtained because the force is found to be attractive and constant for a wide range of quark positions. This work guides future experimental efforts at future Electron-Ion Colliders aimed at obtaining a rigorous quantitative understanding of confinement and the origin of nuclear mass.

   hep-phhep-exhep-latnucl-ex+1Research(2026)·4 citations
6. 06*

   Twist-2 relations for the twist-3 tensor-polarized distribution function $f_{LT}$ of a spin-1 hadron by the operator-product-expansion method

   S. Kumano🇨🇳 · Kenshi Kuroki🇨🇳

   In a spin-1 hadron, tensor-polarized parton distribution functions (PDFs) exist. The twist-2 function is $f_{1LL}$ and a twist-3 one is $f_{LT}$. Because an experiment is under preparation at the Thomas Jefferson National Accelerator Facility (JLab) to measure the cross section of electron-deuteron deep inelastic scattering with the tensor-polarized deuteron target, these PDFs need to be understood theoretically. Especially, measurements will be done in a relatively low-$Q^2$ region at JLab, so that twist-3 contributions could become sizable in the cross section. In a previous work, a twist-2 relation was derived for $f_{LT}$ in terms of $f_{1LL}$ by using a nonlocal operator, and it corresponds to the Wandzura-Wilczek (WW) relation between $g_1$ and $g_2$. In addition, another relation similar to the Burkhardt-Cottingham (BC) sum rule was obtained. It is known that a formal way to derive the WW relation and the BC sum rule is to use the operator product expansion (OPE) with local operators. In this work, the WW-like relation and the BC-like sum rule for $f_{LT}$ are derived by using the local OPE method as a reliable independent way to establish these relations.

   hep-phhep-exhep-latnucl-ex+1PLB(2026)·1 citation
7. 07*

   Nuclear structure and saturation effects from diffractive vector meson production

   Heikki Mäntysaari🇫🇮 · Hendrik Roch🇫🇮 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇨🇳

   We study exclusive vector meson production in ultraperipheral collisions (UPCs) of a wide range of nuclei, and assess the potential of measurements to constrain the small-$x$ structure of oxygen and neon nuclei. We employ an impact-parameter-dependent color glass condensate framework incorporating JIMWLK evolution, with parameters constrained by a recent global Bayesian analysis of $\gamma +p$ and $\gamma +\mathrm{Pb}$ data. We present predictions for coherent and incoherent $\mathrm{J}/\psi$ production in $\mathrm{O}+\mathrm{O}$ and $\mathrm{Ne}+\mathrm{Ne}$ UPCs at LHC energies, and quantify theoretical uncertainties using posterior samples from the calibration. We employ several nuclear structure models and find that $t$-differential observables are sensitive to the chosen model. We further study the mass-number dependence of saturation effects through nuclear suppression factors for coherent and incoherent vector meson production. Saturation-induced suppression increases systematically with both nuclear mass number and energy. Our results provide a unified framework for the systematic study of the onset of gluon saturation and nuclear structure at high energy, accessible in future UPC measurements at the LHC and at the Electron-Ion Collider.

   hep-phnucl-thPRD(2026)·3 citations
8. 08*

   Multiplicative matching of neutral current deep-inelastic scattering processes at next-to-leading order in PYTHIA 8

   Ilkka Helenius🇫🇮 · Joni O. Laulainen🇫🇮 · Christian T. Preuss🇩🇪

   We introduce a method for matching the neutral-current deep inelastic scattering process with parton showers at first order in the strong coupling. This multiplicative matching is achieved by reweighting leading-order Born-level events and requires that the first parton-shower emission is distributed according to the real matrix-element. The method is implemented as an internal matching strategy in the Pythia 8 event generator applicable with both currently available parton shower algorithms, the default one and Vincia. The validity of higher-order corrections is verified with comparisons against existing next-to-leading order simulations. The strategy is used to describe reduced cross-sections measured at the HERA collider, and we find better overall agreement and reduced uncertainties with the matching.

   hep-ph2 citations
9. 09*

   Bounds on massive graviton-like particles from searches for axion-like particles coupling to photons

   Jordan Gué🇪🇸 · David d'Enterria🇨🇭

   Limits on spin-0 axion-like-particles (ALPs) coupling to photons are reinterpreted as constraints on massive spin-2 graviton-like-particles (GLPs) with universal coupling ${\alpha }_{\text{G}}/M_{\text{P}}$ (where $M_{\text{P}}$ is the reduced Planck mass) to the Standard Model fields. A minimally model-dependent recasting is performed, exploiting the formally analogous production and detection mechanisms for both particle types, based on the Primakoff and Gertsenshtein effects, i.e., photon-axion/graviton conversion. Constraints originally derived in the ALP mass vs. photon-coupling plane ($m_{\text{a}},g_{\text{a}\gamma }$) are translated into the corresponding bounds in the GLP ($m_{\text{G}},{\alpha }_{\text{G}}/M_{\text{P}}$) parameter space over the full mass range, $m_{\text{a,G}}\approx 10^{-20}$--$10^{14}$eV probed in current and future experimental setups including cavity-based detectors (haloscopes and resonant upconversion devices), helioscopes, magnetometers, optical interferometers, beam dumps, fixed-target, and collider experiments, as well as astrophysical and cosmological constraints. Generic scenarios are considered in which GLPs are a dark matter candidate and not. Whereas current ALP searches do not set stronger bounds on massive spin-2 particles than fifth-force tests, future magnetometers, two-beam interferometers, and upconversion experiments have the potential to provide very strong sensitivity, down to ${\alpha }_{\text{G}}/M_{\text{P}}\approx 10^{-32}{\text{GeV}}^{-1}$, for light graviton-like particles with $m_{\text{G}}\lesssim 10^{-8}$eV. These future detectors exhibit comparatively greater sensitivity to massive gravitons than to axions. For massive gravitons at the TeV scale, exclusive diphoton decay searches, employed in ALP studies, offer a complementary approach to standard searches for spin-2 resonances in other inclusive final states.

   hep-phastro-ph.HEhep-exnucl-ex+11 citation
10. 10*

    Anisotropy of Cosmic Background Photons from Annihilating/Decaying Dark Matter

    Ryosuke Kasuya🇯🇵 · Kazunori Nakayama🇯🇵

    We provide a detailed formulation for calculating the angular power spectrum of the cosmic background photons arising from the dark matter decay or annihilation in a comprehensive manner. We pay particular attention to the case of dark matter decaying or annihilating into line photons. It is pointed out that taking account of the energy resolution of the detector is essential to correctly evaluate the angular power spectrum. We apply our formulation to the observational data from infrared, optical, X-ray and gamma-ray telescopes.

    hep-phastro-ph.CO0 citations
11. 11*

    Stability of parton distributions at high $x$: impact of nuclear and power corrections

    C. Cocuzza🇺🇸 · W. Melnitchouk🇺🇸 · N. Sato🇺🇸 · A. W. Thomas🇦🇺

    We present a comprehensive new global QCD analysis of unpolarized parton distribution functions (PDFs) based upon proton, deuteron and $A=3$ data, including the latest inclusive deep-inelastic scattering (DIS) measurements from Jefferson Lab at high Bjorken-$x$. Using the JAM Bayesian Monte Carlo framework, we systematically explore the stability of the PDFs with respect to variations in the cuts on the invariant mass $W$ of the DIS final state, the implementation of target mass and higher twist corrections, as well as on the nuclear wave functions for the $A=2$ and 3 data. We find the $u$ and $d$ quark PDFs (and the $d/u$ ratio) are relatively stable up to $x\approx 0.8$, and able to describe DIS data down to $W^2=3.5$ GeV${}^2$ and $Q^2=m_c^2$. Within the collinear factorization framework, the fitted higher twist corrections to DIS are found to be positive, and largely isospin independent. The description of the nuclear data also requires nonzero isoscalar and isovector nucleon off-shell PDF contributions, which gives specific predictions for the ratio, $R_D$, of deuteron to isoscalar nucleon structure functions.

    hep-phhep-exnucl-th5 citations
12. 12*

    Color Decompositions of the Two Loop Amplitudes of Yang-Mills theory

    David C. Dunbar🇬🇧

    The color structure of two-loop gluon amplitudes is examined both from a color trace basis expansion and an alternative based upon structure constants. We use use this as a vehicle for systemising relations between the partial amplitudes of the color trace formalism.

    hep-phhep-th1 citation
13. 13*

    Phenomenology of Hypothetical Single-Top Hadronic States

    Z. Rajabi Najjar🇮🇷 · M. Ahmadi🇮🇷 · K. Azizi🇮🇷

    We present a comprehensive theoretical study of the masses of possible baryonic and mesonic configurations containing a single top quark. Our analysis includes the baryons ${\Lambda }_t$, ${\Xi }_t$, ${\Sigma }_t$, ${\Xi }_t^{\prime }$, ${\Omega }_t$, ${\Omega }_{tcc}$, and ${\Omega }_{tbb}$, together with the pseudoscalar and vector mesons $T_{t\bar{n}}^{\mathrm{Ps}}$, $T_{t\bar{n}}^{\mathrm{V}}$, $T_{t\bar{s}}^{\mathrm{Ps}}$, $T_{t\bar{s}}^{\mathrm{V}}$, $T_{t\bar{c}}^{\mathrm{Ps}}$, $T_{t\bar{c}}^{\mathrm{V}}$, $T_{t\bar{b}}^{\mathrm{Ps}}$, and $T_{t\bar{b}}^{\mathrm{V}}$. Motivated in part by recent experimental indications of a pseudoscalar enhancement near the $t\bar{t}$ threshold reported by the CMS and ATLAS collaborations, this study is carried out within the framework of two-point QCD sum rules to determine the corresponding ground-state masses by including perturbative contributions and nonperturbative condensates up to dimension eight. For several channels, including the ${\Lambda }_t$, ${\Xi }_t$, ${\Sigma }_t$, $T_{t\bar{b}}^{\mathrm{Ps}}$, and $T_{t\bar{b}}^{\mathrm{V}}$ states, the extracted central masses lie slightly below the corresponding sums of constituent quark masses, which may indicate nontrivial binding dynamics or near-threshold multiquark configurations within the uncertainties of the method. Moreover, when the full theoretical uncertainties are taken into account in a conservative manner, a larger subset of the investigated states exhibits a consistent tendency toward weak binding behavior, suggesting that the possibility of loosely bound configurations cannot be excluded for most of the considered baryonic and mesonic channels. These results provide useful first-principles theoretical benchmarks for possible top-containing hadronic systems, which may support future searches at the LHC, along with sensitivity analyses for next-generation facilities such as the FCC.

    hep-phhep-exhep-latAnnals Phys.(2026)·0 citations
14. 14*

    W-boson helicity fractions in top decay as probes of dimension-6 and dimension-8 SMEFT operators

    Afsaneh Kianfar🇮🇷 · Gholamhossein Haghighat🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

    Precision measurements of top-quark decays provide powerful probes of physics beyond the Standard Model (SM). While the impact of dimension-6 operators in the SM Effective Field Theory (SMEFT) has been extensively studied, the role of dimension-8 contributions remains largely unexplored, despite their potential importance as experimental precision improves. In this work, we present a combined analysis of dimension-6 and a representative subset of dimension-8 SMEFT effects using the W-boson helicity fractions in top-quark decays. We compute the leading-order contributions of these operators to the top-quark decay width and helicity fractions, and perform one-parameter and selected two-parameter ${\chi }^2$ fits to the combined ATLAS and CMS measurements at a reference scale $\Lambda =1$~TeV. From the fit results, we find that the inclusion of dimension-8 contributions affects the allowed parameter space of several dimension-6 coefficients through non-trivial correlations and degeneracies. Since the leading dimension-8 contributions enter at the same order $\mathcal{O}({\Lambda }^{-4})$ as the squared dimension-6 terms retained in our analysis, this highlights the importance of a consistent treatment of the EFT expansion when interpreting SMEFT constraints.

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

    $CP$ violation in neutral kaon mixing in $D^0\to K_S{K}_S$

    Yuval Grossman🇺🇸 · Guglielmo Papiri🇺🇸 · Stefan Schacht🇬🇧

    We study CP violation induced by neutral kaon mixing in $a_{CP}(D^0\to K_S{K}_S)$. We show that the contribution from neutral kaon mixing arises only in connection with second-order weak interactions in $D$ decays. We estimate this effect to be at the $10^{-6}$ level, and thus negligible compared to current experimental sensitivity and to the expected contribution from CP violation in the charm sector.

    hep-phhep-ex1 citation
16. 16*

    Comment on "Controlling the dynamical evolution of quantum coherence and quantum correlations in $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ processes at BESIII''

    Saeed Haddadi🇮🇷

    We critically examine recent claims [Phys. Rev. D 113, 016024 (2026)] regarding quantum coherence, steering, and non-Markovian dynamics in the hyperon-antihyperon system produced in the process $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$. We argue that the theoretical framework employed in the analyzed work suffers from fundamental physical inconsistencies. In particular, the treatment of the $\Lambda \bar{\Lambda }$ pair as a bipartite system evolving under correlated quantum channels is not physically justified, since the produced hyperons are free, unstable particles that do not interact with a common environment after production. Consequently, the application of open quantum system techniques, including Markovian and non-Markovian quantum channels, lacks a clear physical basis. Moreover, we show that the computation and interpretation of quantum steering for this system is operationally and conceptually meaningless, as no well-defined measurement-induced state update or controllable local measurement scenario exists for unstable relativistic particles. These issues call into question the physical relevance of the reported quantum correlations, their hierarchy, and their dynamical behavior. Our analysis highlights the necessity of carefully distinguishing between formal mathematical quantifiers of quantumness and physically realizable quantum information protocols in high-energy particle systems.

    ↳ quant-phhep-phPRD(2026)·1 citation
17. 17*

    Comment on "Quantum teleportation, entanglement, LQU and LQFI in $e^{+}{e}^{-}\to \mathrm{Y}\overline{\mathrm{Y}}$ processes at BESIII through noisy channels''

    Saeed Haddadi🇮🇷

    We provide a critical assessment of a recent study applying quantum information concepts, including noisy channels and teleportation fidelity, to hyperon-antihyperon pairs produced in $e^{+}{e}^{-}\to Y\bar{Y}$ reactions at BESIII. While the spin density matrix reconstructed from experimental data provides a physically meaningful description of production correlations, we argue that its subsequent interpretation in terms of standard decoherence models-such as amplitude damping, phase damping, and phase flip-lacks a clear physical correspondence for these systems. The produced particles emerge from a single scattering event and propagate as free, unstable relativistic states, without a well-defined system-environment interaction acting on their spin degrees of freedom. As a result, the variation of quantum correlations with an abstract noise parameter does not describe a genuine physical evolution. We further contend that the reported teleportation fidelity should not be interpreted as evidence for operational quantum communication, since hyperon states cannot be prepared, controlled, or measured in a way that would enable a realizable teleportation protocol. More generally, quantities such as logarithmic negativity, local quantum uncertainty, and local quantum Fisher information primarily characterize static production correlations rather than directly usable quantum resources. Our analysis highlights the importance of distinguishing between formal quantum-information measures and their physical interpretation in high-energy particle systems.

    ↳ quant-phhep-ph0 citations
18. 18*

    Topological charges and confined-deconfined phase transition in holography

    Nelson R. F. Braga🇧🇷 · William S. Cunha🇧🇷

    In recent years, many interesting works providing a topological description for black hole (BH) properties have appeared in the literature. In particular, in this framework BHs correspond to topological defects in an enlarged (off-shell) parameter space, with an associated total topological charge. In gauge/gravity duality the transition from the confined to the deconfined phase is mapped into the dominance of a BH phase in the gravity side. Here we show, using a holographic AdS/QCD model, that the introduction of an energy scale in anti-de Sitter (AdS) space results in a change in the topological class. Such a modification corresponds to the existence of confined and deconfined phases, separated by a Hawking Page transition at a finite critical temperature.

    ↳ hep-thgr-qchep-phPRD(2026)·0 citations
19. 19*

    Cosmic Ray Physics with the KM3NeT Telescopes

    Brían Ó Fearraigh (on behalf of the KM3NeT Collaboration)

    The KM3NeT research infrastructure instruments a large volume of seawater using photomultiplier tubes, which are sensitive to the Cherenkov radiation stimulated by the products of neutrino interactions in the water, as well as that stimulated by atmospheric muons which penetrate the sea depths. The KM3NeT/ARCA and KM3NeT/ORCA detectors are situated at different depths in the Mediterranean Sea, with different extension and densities of the photo-detection elements. Although operating independently, taken as a whole the two detectors provide a wide energy coverage for the atmospheric muons flux. Through the detection and analysis of these atmospheric muons, a variety of physics studies are possible with the KM3NeT telescope. A measurement of the atmospheric muon neutrino flux has been carried out with data from the initial six detection units of the KM3NeT/ORCA detector. Relatedly to the atmospheric muon flux, the recent atmospheric lepton model `Daemonflux' has been incorporated into the KM3NeT Monte Carlo event generator for atmospheric muon bundles. This has resulted in a stark alleviation of the atmospheric muon data-Monte Carlo simulation discrepancy - a systemic issue in cosmic ray experiments referred to as the `Muon Puzzle' - and a comprehensive description of the atmospheric muon data in KM3NeT. These atmospheric muons are also used in the calibration of the detectors, as well as constraining systematic uncertainties in the detectors such as the optical properties of the instrumented seawater. An overview of these topics, and other cosmic ray analyses, is presented.

    ↳ hep-exhep-ph0 citations
20. 20*

    Maximal mass of neutron stars constrained by neutron star observations

    Gábor Kasza🇭🇺 · György Wolf🇭🇺

    We investigate constraints on the high-density equation of state (EOS) of neutron star matter by analyzing the probability distributions of the endpoints of mass-radius M(R) sequences within a Bayesian weighting framework. Starting from two representative hadronic baseline EOSs, SFHo and DD2, matched at higher densities to an extended linear sigma model description and constrained to approach perturbative QCD (pQCD) results, we construct families of causal hybrid EOSs spanning a broad range of stiffness at supranuclear densities. Observational constraints from the binary neutron-star merger GW170817, mass-radius measurements from the Neutron Star Interior Composition Explorer (NICER), and candidate low-mass and mass-gap compact objects are incorporated through Bayesian likelihood weighting. This approach allows us to determine probability distributions for the maximum neutron-star mass M${}_{\mathrm{TOV}}$ and the corresponding radius R${}_{\mathrm{TOV}}$, i.e., the endpoints of the M(R) sequences. We find that the maximum-mass distributions are largely determined by observational constraints and show only weak sensitivity to the choice of baseline EOS, favoring values around 2.2-2.3 M${}_{\odot }$ when the most robust constraints are applied. In contrast, the corresponding radius distributions exhibit a stronger dependence on the underlying hadronic EOS, with typical preferred values near $12\pm 1$ km. Additional tidal-deformability constraints further restrict the allowed parameter space and disfavor very stiff EOS realizations when interpreted together with the possible mass-gap neutron-star candidate. Our results demonstrate that endpoint distributions of M(R) sequences provide a sensitive and complementary diagnostic for constraining the high-density behavior of the neutron-star EOS within a multimessenger Bayesian framework.

    ↳ astro-ph.HEhep-phnucl-thJ.Subatomic Part.Cosmol.(2026)·1 citation
21. 21*

    Multi-messenger Constraints on a Primordial Black Hole Origin of the KM3-230213A Event

    Yuber F. Perez-Gonzalez🇪🇸

    Black holes are expected to end their lifetime in a burst of Hawking radiation, emitting all Standard Model particles at ultra-high energies. The evaporation of a nearby primordial black hole (PBH) has been proposed as an explanation for the high-energy neutrino-like event reported by KM3NeT. Such a scenario requires the source to be extremely close to Earth, implying detectable gamma-ray and cosmic-ray emission. Accounting for the time-dependent field of view of gamma-ray observatories, we find that current experiments should have observed a pre-burst signal, while neutrino telescopes would also detect lower-energy events before the burst. The absence of such multimessenger signals strongly disfavors a PBH origin of the KM3-230213A event in the minimal 4D Schwarzschild scenario.

    ↳ astro-ph.HEhep-ph0 citations
22. 22*

    Non-Supersymmetric Baryogenesis from $U(1)$-Breaking Scalar Dynamics

    Surendra Kumar Gour🇮🇳 · Malay K. Nandy🇮🇳

    We present a non-supersymmetric mechanism for baryogenesis driven by the nonlinear dynamics of a complex scalar field with generalized self-interaction potentials that explicitly break the global $U(1)$ symmetry. Specifically, three representative forms of the interaction potential are considered, which give rise to intricate nonlinear source terms in the evolution of the field components. In all cases, we show that these nonlinear source terms dynamically generate a nonzero Noether charge density from symmetric initial conditions, providing a purely dynamical origin of charge asymmetry. At late times, the charge density scales as $\sim t^{-3/2}$, leading to a constant baryon-to-photon ratio through dynamical freeze-in. While the qualitative behavior is robust across models, the quantitative features depend sensitively on the interaction structure. We find that one class of potentials yields a viable parameter space over a wide range of scalar masses, whereas another requires unrealistically suppressed mass scales. A third scenario stands out in that the final asymmetry is independent of the scalar mass and depends only on the coupling parameter, enhancing predictivity and allowing compatibility across a broad range of energy scales. Assuming efficient transfer of the generated asymmetry to the Standard Model sector and negligible washout effects, the mechanism can account for the observed baryon asymmetry.

    ↳ gr-qchep-ph0 citations
23. 23*

    Implications of SARAS3 data for Coulomb-like interacting dark matter

    Shikhar Mittal🇨🇳 · Prakhar Bansal🇨🇳 · Harry Bevins🇨🇳 · Saurabh Singh🇨🇳

    The 21-cm signal from cosmic dawn is a potentially sensitive probe of interactions between dark matter (DM) and baryons. We investigate the implications of the SARAS3 non-detection in the 55.5-84.4 MHz band for Coulomb-like interacting DM (IDM). In contrast to earlier constraint analyses that focused primarily on baryon cooling, we model the interaction self-consistently by including both excess cooling of the gas and the suppression of structure formation, which delays the onset of star formation and hence suppresses the Ly$\alpha$, X-ray, and ionizing backgrounds at early times. We perform a joint Bayesian fit of a global 21-cm signal model and a flexible foreground model to the SARAS3 antenna temperature, and find that the signal parameters remain weakly constrained after marginalizing over the foregrounds. The null result is nonetheless informative: the data disfavour deep absorption features within the observed band, with the strongest bound at $z=23.6$ ($\nu \approx 57.7$ MHz), where $T_{21}\gtrsim -277.6$ mK at $3\sigma$. Comparing the IDM and standard cold dark matter scenarios, we find no statistically significant preference for IDM (Bayes factor $B\approx 1.7$). While we do not constrain the strength of baryon-DM interactions, the SARAS3 non-detection places a meaningful upper bound on the amplitude of the global 21-cm signal in this class of models.

    ↳ astro-ph.COhep-phJCAP(2026)·1 citation

* 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.