Mon·Nov 10, 2025Monday·November 10, 2025

1. 01*

   Helicity amplitude for the process $q\text{Bar}q\to q\text{Bar}qg$

   Vibhu Pandya🇮🇳 · Radhika Vinze🇮🇳 · Anuradha Misra🇮🇳

   Precision calculations in hadronic processes at high energy colliders are crucial for improving the understanding of the standard phenomena as well as for the discovery of new physics. Spinor-helicity formalism serves as one of the most efficient ways to simplify the calculations of $S$ matrix elements. In this article, we compute the $S$ matrix elements for the process $q\text{Bar}q\to q\text{Bar}qg$ mediated by photon and gluon. Ignoring the contribution of $Z$ boson exchange, we show that the calculation of $S$ matrix elements for this process simplifies to a great extent by using spinor-helicity formalism.

   hep-phhep-th0 citations
2. 02*

   Millicharged Particle Production in Pulsars via the Schwinger Effect

   Chris Kouvaris🇬🇷 · Ian M. Shoemaker🇺🇸

   Low mass particles with small electric charges can be produced abundantly in large electric fields via the Schwinger effect. We study the production rate of such particles inside the polar gap of nearby pulsars. After production they are accelerated above MeV energies by the local electric fields. These pulsar-produced millicharged particles can be detected at Earth in low-threshold dark matter direct detection experiments. We find that the current XENONnT data constrains millicharged particles produced in the Crab pulsar to have charges less than $O(10^{-6})$ for sub-eV masses.

   hep-phastro-ph.HEhep-ex3 citations
3. 03*

   Interpretation of LHC excesses at 95 GeV and 152 GeV in an extended Georgi-Machacek model

   Ting-Kuo Chen🇺🇸 · Cheng-Wei Chiang🇹🇼 · Sven Heinemeyer🇪🇸 · Georg Weiglein🇩🇪

   We analyze the excesses at 95 GeV in the light Higgs-boson searches in the di-photon decay channel reported by CMS and ATLAS, which combined are at the level of three standard deviations and are compatible with the excess in the $b\bar{b}$ final state observed at LEP, together with an excess in the di-photon channel at around 152 GeV reported based on a sideband analysis. We demonstrate that these excesses can be well described in a minimally extended Georgi-Machacek (meGM) model. This is enabled by four key features of the meGM model: (1) a natural prediction for scalar boson masses of $\lesssim$200 GeV arising from the condition to describe both the Higgs boson signal at 125 GeV and the excesses at 95 GeV, (2) the prediction for a doubly charged Higgs boson that can potentially enhance the di-photon decay rates, (3) asymmetric $WW$ and $ZZ$ couplings to neutral scalar bosons that are induced by mild custodial symmetry breaking, and (4) the approximate preservation of the electroweak $\rho$ parameter to be 1 at tree level. We show in our numerical analysis that the meGM model naturally improves the fit to the LHC data around 152 GeV when describing the excesses at 95 GeV. At the same time, the model also predicts additional light CP-odd and charged scalar bosons that can be potentially probed in future experiments, which motivates dedicated searches in the upcoming LHC runs. We also present the results of sensitivity studies for the 95 and 125 GeV Higgs-boson couplings at the HL-LHC and future $e^{+}{e}^{-}$ colliders, which demonstrate very interesting prospects for probing the meGM model at future colliders.

   hep-phhep-exPRD(2026)·7 citations
4. 04*

   Are Subleading Effects Really Subleading? $B$-Meson Decays in Mesogenesis

   Ali Mohamed🇩🇪

   We calculate inclusive $B$-meson decay rates in the Mesogenesis framework, a model explaining baryogenesis and the existence of dark matter, using the Heavy Quark Expansion (HQE), up to the dimension-six two-quark Darwin term. By systematically studying the power-suppressed contributions, we identify regions of parameter space where subleading terms exceed the leading contribution, i.e., the free $b$-quark decay, highlighting the limits of the HQE in this BSM scenario. This behavior is reminiscent of the Standard Model only under artificially heavy charm masses, and can be used to study the HQE close to its breakdown. We further update the lower bounds on the exclusive decay mode $B^{+}\to p^{+}\psi$ by incorporating the fully HQE-corrected inclusive width in the ratio ${\Gamma }_{\mathrm{excl}}/{\Gamma }_{\mathrm{incl}}$. Extending the analysis from total decay rates to the lifetime ratio $\tau (B_s)/\tau (B_d)$, we find no additional constraints on the couplings beyond existing collider bounds, consistent with analogous results for $\tau (B^{+})/\tau (B_d)$. We further compare the sensitivity of both lifetime ratios.

   hep-phhep-exJHEP(2026)·4 citations
5. 05*

   Low-reheating scenario in dark Higgs inflation and its impact on dark photon dark matter production

   Sarif Khan🇰🇷 · Jinsu Kim🇨🇳 · Pyungwon Ko🇰🇷

   We investigate dark matter (DM) phenomenology and cosmic inflation within a unified framework based on a dark $U(1{)}_D$ gauge extension of the Standard Model (SM). The associated dark gauge boson, namely the dark photon, serves as a viable DM candidate, which we call dark photon dark matter (DPDM), whilst the dark Higgs field drives inflation. We explore a low-reheating scenario where DM production occurs during reheating, resulting in significant entropy dilution of the DPDM abundance. Both weakly interacting massive particle (WIMP) and feebly interacting massive particle (FIMP) DM scenarios are explored, depending on the dark gauge coupling strength. For FIMP-type DM, the entropy dilution allows for stronger couplings whilst maintaining the correct relic abundance, potentially bringing these candidates within the reach of current and near-future detection experiments. Similarly, WIMP-type DM can be realised with weaker couplings. We perform a comprehensive parameter scan incorporating constraints from collider data, DM direct and indirect detection experiments, and cosmological observations. Taking quantum corrections and running of the couplings into account, we demonstrate that dark Higgs inflation yields predictions for the spectral index $n_s$ and the tensor-to-scalar ratio $r$ that are consistent with the Planck, BICEP/Keck, and ACT data. The nonminimal coupling of the dark Higgs inflaton field to gravity is shown to be much smaller than in the case of the SM Higgs inflation scenario, avoiding unitarity concerns. We show that reheating temperatures as low as 1 GeV and 1 MeV can be achieved through the decay and scattering processes of the inflaton, respectively, with the latter allowing for larger Higgs mixing angles and enhanced detection prospects. Our results establish that this minimal extension successfully unifies DM physics with inflationary cosmology.

   hep-phastro-ph.COJHEP(2026)·345 citations
6. 06*

   Scalar Resonances near 650 and 95 GeV in the GNMSSM with Correct Dark Matter Relic Abundance

   Jingwei Lian🇨🇳 · Yao-Bei Liu🇨🇳

   Recent CMS analyses report an excess in the diphoton-plus-$b\bar{b}$ channel, indicative of a heavy resonance around 650 GeV decaying into a Standard Model (SM)-like Higgs boson and a lighter scalar near 95 GeV. The case for a 95 GeV state is further supported by diphoton excesses observed by both CMS and ATLAS, as well as a $b\bar{b}$ excess previously observed at the Large Electron-Position collider. This study presents a unified interpretation of these anomalies within the framework of the General Next-to-Minimal Supersymmetric Standard Model that naturally accommodates a light singlet-dominated $CP$-even scalar boson $h_s$ near 95 GeV and a heavier doublet-like scalar boson $A_H$ near 650 GeV. Through a comprehensive scan of the parameter space, we demonstrate that the model can explain these excesses at $2\sigma$ level while satisfying constraints from the dark matter relic density, direct detection experiments, the properties of the 125 GeV Higgs boson, $B$-physics observables, and searches for electroweakinos at the Large Hadron Collider (LHC). The interpretation features a Bino-dominated lightest neutralino as the dark matter candidate, whose relic abundance is achieved primarily via $A_s$ funnel annihilation or coannihilation with $\tilde{S}$-like ${\tilde{\chi }}_2^0$s into $h_s{A}_H$ final states. Our findings provide clear predictions for testing this scenario at the high-luminosity LHC and future colliders.

   hep-phJHEP(2026)·2 citations
7. 07*

   Physics-informed neural network (PINN) modeling of charged particle multiplicity using the two-component framework in heavy-ion collisions: A comparison with data-driven neural networks

   Akash Das🇮🇳 · Satya Ranjan Nayak🇮🇳 · B. K. Singh🇮🇳

   In this study, we employ a conventional deep neural network (NN) framework integrated with physics-based constraints to predict charged hadron multiplicity ($N_{\text{ch}}$) in heavy-ion collisions. The goal is to assess the performance of a purely data-driven deep neural network in comparison to a physics-informed neural network (PINN). To accomplish this, we have taken data generated from the HYDJET++ model for testing and training purposes. We train our neural network frameworks using the data of one million individual ${}_{40}^{96}\text{Zr}{+}_{40}^{96}\text{Zr}$ collision events. Our PINN model successfully extracts the hard-scattering fraction ($x$) by learning its underlying relation from the event data. For further testing and comparison with the conventional NN, we take data of ${}_{44}^{96}\text{Ru}{+}_{44}^{96}\text{Ru}$ (isobar of Zr) and ${}_{79}^{197}\text{Au}{+}_{79}^{197}\text{Au}$ collisions using the same simulation model. We found that the NN model needs more time to train with physics. However, once trained, the PINN model is capable of accurately predicting data that it has not encountered during training, such as Au+Au collision results. Especially in a region of sparse data corresponding to high $N_{\text{ch}}$ in our study, PINN has a clear advantage over a simple NN.

   hep-phEur.Phys.J.Plus(2026)·0 citations
8. 08*

   Inflationary Particle Production and Implications for WIMP Substructure

   María Olalla Olea-Romacho🇬🇧

   We explore the observational consequences of resonant particle production during inflation, focusing on its impact on dark matter annihilation signals today. A transient burst of particle production generates localised features in the primordial power spectrum, enhancing the formation of compact small-scale dark matter structures known as prompt cusps. If dark matter consists of thermal WIMPs, the resulting small-scale structures substantially boost annihilation rates, leaving potentially detectable imprints in gamma-ray observations. Using 15 years of Fermi-LAT data targeting the Virgo cluster, we derive upper limits on the thermally averaged annihilation cross section $⟨\sigma v⟩$, connecting inflationary particle production in the early universe with present-day observations constraining dark matter annihilation.

   hep-phPRD(2026)·3 citations
9. 09*

   Neutrino-Nucleus Scattering Cross Sections at Medium Energies

   Vishvas Pandey🇺🇸

   The weak interactions of neutrinos with other Standard Model particles are well described within the Standard Model of particle physics. However, modern accelerator-based neutrino experiments employ nuclei as targets, where neutrinos interact with bound nucleons, turning a seemingly simple electroweak process into a complex many-body problem in nuclear physics. At the time of writing this Encyclopedia of Particle Physics chapter, neutrino-nucleus interactions remain one of the leading sources of systematic uncertainty in accelerator-based neutrino oscillation measurements. This chapter provides a pedagogical overview of neutrino interactions with nuclei in the medium-energy regime, spanning a few hundred MeV to several GeV. It introduces the fundamental electroweak formalism, outlines the dominant interaction mechanisms - including quasielastic scattering, resonance production, and deep inelastic scattering - and discusses how nuclear effects such as Fermi motion, nucleon-nucleon correlations, meson-exchange currents, and final-state interactions modify observable cross sections. The chapter also presents a brief survey of the foundational and most widely used theoretical models for neutrino-nucleus cross sections, together with an overview of current and upcoming accelerator-based neutrino oscillation experiments that are shaping the field. Rather than targeting experts, this chapter serves as a primer for advanced undergraduates, graduate students, and early-career researchers entering the field. It provides a concise foundation for understanding neutrino-nucleus scattering, its relevance to oscillation experiments, and its broader connections to both particle and nuclear physics.

   hep-phhep-exnucl-thEncyclopedia of Particle Physics, Elsevie…·6 citations
10. 10*

    $D$-Dimensional Modular Assembly of Higher-Derivative Four-Point Contact Amplitudes Involving Fermions

    John Joseph M. Carrasco🇺🇸 · Sai Sasank Chava🇺🇸 · Alex Edison🇺🇸 · Aslan Seifi🇺🇸

    We present a novel robust framework for systematically constructing $D$-dimensional four-point higher-derivative contact amplitudes. Our modular block ("LEGO"-like) approach builds amplitudes directly from manifestly gauge-invariant kinematic blocks, color-weight factors, and scalar Mandelstam polynomials. Symmetries (Bose/Fermi) are imposed algebraically, acting as filters on combinations of compatible pieces. This framework operates entirely in $D$ dimensions, naturally incorporating evanescent operators crucial for loop-level consistency. Scaling to arbitrary mass dimension is achieved in a highly controlled manner using permutation-invariant scalar polynomials, avoiding combinatorial explosion. A key feature is its manifest compatibility with the double-copy program, allowing the systematic generation of operator towers not only for gauge theories but also for gravity and other theories within the double-copy web.

    hep-phhep-thJHEP(2026)·1 citation
11. 11*

    The $Z{\alpha }^2$ correction to superallowed beta decays in effective field theory and implications for $|V_{ud}|$

    Zehua Cao🇺🇸 · Richard J. Hill🇺🇸 · Ryan Plestid🇺🇸 · Peter Vander Griend🇺🇸

    Superallowed ($0^{+}\to 0^{+}$) beta decays currently provide the most precise extraction of quark mixing in the Standard Model. Their interpretation as a measurement of $|V_{ud}|$ relies on a reliable first-principles computation of QED radiative corrections expressed as a series in $Z\alpha$ and $\alpha$. In this work, we provide the first model-independent result for two-loop, $O(Z{\alpha }^2)$, long-distance radiative corrections where the nuclei are treated as heavy point-like particles. We use renormalization group analysis to obtain new results at $O(Z{\alpha }^3)$ for the coefficient of double-logarithms in the ratio of the maximal beta energy to the inverse nuclear size, $\text{Em}/R^{-1}$. We use the Kinoshita-Lee-Nauenberg theorem to obtain new results at $O(Z^2{\alpha }^3)$ for the coefficient of logarithms in the ratio of maximal beta energy to the electron mass, $\log (2\text{Em}/\text{me})$. We identify a structure-dependent, and therefore short-distance, contribution to the traditional $Z{\alpha }^2$ correction that should be revisited.. We provide the first comprehensive update to the long-distance corrections in almost forty years and comment on the impact of our findings for extractions of $|V_{ud}|$. We find that shifts in the long-distance corrections are $2.5\times$ larger than past estimates of their uncertainty, $1.5\times$ larger than the statistical uncertainty from the combined fit of superallowed decays, and about $1/2$ the size of estimated systematic error, which stems dominantly from nuclear structure effects.

    hep-phnucl-exnucl-thPRD(2026)·11 citations
12. 12*

    Radiative corrections to superallowed beta decays at $\mathcal{O}({\alpha }^{2}Z)$

    Òscar L. Crosas🇨🇭 · Emanuele Mereghetti🇺🇸

    We compute $\mathcal{O}({\alpha }^{2}Z)$ radiative corrections to superallowed $\beta$ decays with a heavy-particle effective field theory that systematically describes the interactions of low-energy ultrasoft photons with nuclei. We calculate two-loop virtual and one-loop real-virtual amplitudes by reducing the Feynman integrals to a set of master integrals, which we solve analytically using a variety of techniques. These techniques can be applied to other phenomenologically interesting observables. The ultrasoft corrections can then be combined with contributions arising from the exchange of potential photons to obtain the complete $\mathcal{O}({\alpha }^{2}Z)$ correction to the decay rate, with resummation of large logarithms of the electron energy times the nuclear radius. We find that $\mathcal{O}({\alpha }^{2}Z)$ ultrasoft loops induce a relative correction to the decay rate that ranges from $0.7\cdot 10^{-3}$ in the decay of ${}^{10}$C to $3.6\cdot 10^{-3}$ in the decay of ${}^{54}$Co, and will thus impact the extraction of $V_{ud}$ at the permille level. We show that the inclusion of these corrections reduces the residual renormalization scale dependence of the decay rate to a negligible level, making missing ultrasoft perturbative corrections a subdominant source of theoretical error.

    hep-phhep-exnucl-exnucl-thJHEP(2026)·10 citations
13. 13*

    Neutron stars can shine a light on elusive lepton-flavor-violating dark matter

    Hooman Davoudiasl🇺🇸 · Jaime Hoefken Zink🇵🇱 · Sebastian Trojanowski🇵🇱

    We investigate a scenario in which dark matter (DM) poses a challenge to conventional direct and indirect detection, making it much more elusive than typical candidates. We focus on thermally produced DM that couples to electrons and muons via a lepton-flavor-violating (LFV) axion-like particle (ALP). Given the DM kinematics and lack of muon targets on Earth, direct detection would be infeasible. Indirect detection of our DM candidate is also hampered by the dominance of $p$-wave annihilation. However, we demonstrate that neutron stars (NS) can serve as probes of such a scenario, through future dedicated observational campaigns. Infalling DM is accelerated to semi-relativistic velocities, triggering inelastic $\chi e\leftrightarrow \chi \mu$ scattering off both electrons and muonic targets within the NS. We show that ``flavor blocking'' -- the kinematic suppression of LFV interactions at low energies -- prevents DM thermalization with the cold neutron star, enabling efficient $p$-wave annihilations. The resulting NS surface temperatures ($T_s\gtrsim 2\times 10^3\mathrm{K}$) offer a possible signature for future infrared searches, probing thermal relics beyond the reach of direct, indirect, and accelerator experiments.

    hep-phJHEP(2026)·4 citations
14. 14*

    Probing Lepton Flavour Universality with ${\Lambda }_b$ decays to ${\tau }^{+}{\tau }^{-}$ final states

    Marzia Bordone🇨🇭 · Gino Isidori🇨🇭 · Christiane Mayer🇨🇭 · Jan-Niklas Toelstede🇨🇭

    We present a study of the rare baryonic decay ${\Lambda }_b\to \Lambda {\tau }^{+}{\tau }^{-}$ as a probe of new physics (NP) coupled preferentially to third-generation fermions. Within the Standard Model, we evaluate the branching ratio and the lepton-flavour-universality (LFU) ratio $R_{\Lambda }^{\tau /\mu }$, including both perturbative and long-distance charm contributions. We show that the LFU ratio can be predicted with an uncertainty below 10%. Possible NP effects arising from lepton non-universal dynamics are analysed within an effective field theory framework motivated by the current anomalies in $b\to c\tau \nu$ and $b\to s{\mu }^{+}{\mu }^{-}$ transitions. In this context, $R_{\Lambda }^{\tau /\mu }$ can be enhanced by several orders of magnitude, offering a clear target for upcoming searches. The implications for the related mode ${\Lambda }_b\to pK{\tau }^{+}{\tau }^{-}$ are also briefly discussed.

    hep-phEPJC(2026)·2 citations
15. 15*

    New Avenues for $|\Delta B|$ = 2 Processes Beyond Neutron-Antineutron Oscillations

    Arnau Bas i Beneito🇪🇸 · Svjetlana Fajfer🇸🇮 · Alexey A. Petrov🇺🇸

    We explore baryon-number-violating ($|\Delta B|=2$) processes beyond the well-known neutron-antineutron ($n-\bar{n}$) oscillations, focusing on the $\Lambda -\bar{\Lambda }$ system. The presence of a strange quark in the $\Lambda$ baryon introduces a new set of six-quark operators roughly of the form $(uds{)}^2$, which are different from the $(udd{)}^2$ operators responsible for $n-\bar{n}$ oscillations. Using the Standard Model Effective Field Theory (SMEFT), we classify all dimension-9 operators that cause $|\Delta B|=2$ transitions and study their UV completions mediated by exotic scalar fields with trilinear interactions. We demonstrate that in these models, $\Lambda -\bar{\Lambda }$ oscillations can occur at tree level, with $n-\bar{n}$ mixing potentially appearing at higher loop levels. We employ a chiral effective theory to constrain the effective mass mixing $\delta m_{\Lambda }$, deriving bounds from current experimental limits on $n-\bar{n}$ oscillations and dinucleon decays such as $pp\to K^{+}{K}^{+}$. These bounds indicate that $\Lambda -\bar{\Lambda }$ oscillations probe a complementary parameter space, sensitive to baryon-number violation at scales up to $10^2-10^3$ TeV. We show that the existing indirect bounds make it challenging to provide a competitive bound on $\delta m_{\Lambda }$ at BESIII.

    hep-phJHEP(2026)·2 citations
16. 16*

    QCD in AdS

    Riccardo Ciccone🇮🇱 · Fabiana De Cesare🇫🇷 · Lorenzo Di Pietro🇮🇹 · Marco Serone🇮🇹

    We study QCD on AdS space with scalars or fermions in the fundamental representation, extending earlier results on pure Yang-Mills theory. In the latter, the Dirichlet boundary condition is conjectured to disappear via merger and annihilation, as signaled by the lightest scalar singlet operator approaching marginality as the coupling increases. With matter, there are two candidate operators for this mechanism. We compute their one-loop anomalous dimensions via broken conformal Ward identities and Witten diagrams. In the confining phase, with Dirichlet (Neumann) boundary condition, their anomalous dimensions are negative (positive), consistent with the disappearance (persistence) of the associated boundary CFT in the flat-space limit. In the conformal window, one of these operators becomes the displacement operator of the IR CFT, as signaled by the vanishing of its one-loop anomalous dimension in the perturbative Banks-Zaks regime. Possible scenarios for the lower edge of the conformal window are discussed. Finally, we consider general boundary conditions on fermions and discuss their relation to chiral symmetry breaking in flat space.

    ↳ hep-thhep-lathep-phJHEP(2026)·17 citations
17. 17*

    Probing Lorentz Invariance Violation at High Energies Using LHAASO Observations of GRB221009A via DisCan Algorithm

    Yu-Chen Hua🇨🇳 · Xiao-Jun Bi🇨🇳 · Yu-Ming Yang🇨🇳 · Peng-Fei Yin🇨🇳

    The Lorentz invariance violation (LIV) predicted by some quantum gravity theories would manifest as an energy-dependent speed of light, which may potentially distort the observed temporal profile of photons from astrophysical sources at cosmological distances. The dispersion cancellation (DisCan) algorithm offers a powerful methodology for investigating such effects by employing quantities such as Shannon entropy, which reflects the initial temporal characteristics. In this study, we apply the DisCan algorithm to search for LIV effects in the LHAASO observations of GRB 221009A, combining data from both the WCDA and KM2A detectors that collectively span an energy range of $\sim 0.2-13$ TeV. Our analysis accounts for the uncertainties from both energy resolution and temporal binning. We derive $95\%$ confidence level lower limits on the LIV energy scale of $E_{\mathrm{QG}}/10^{19}\text{GeV}>21.1$ (13.8) for the first-order subluminal (superluminal) scenario, and $E_{\mathrm{QG}}/10^{11}\text{GeV}>14.9$ (13.7) for the second-order subluminal (superluminal) scenario.

    ↳ astro-ph.HEgr-qchep-phUniverse(2026)·1 citation
18. 18*

    Exact Renormalisation Group Evolution of the Inflation Dynamics: Reconciling $\alpha$-Attractors with ACT

    Jean Alexandre🇬🇧 · Lucien Heurtier🇬🇧 · Silvia Pla🇩🇪

    We present a non-perturbative framework for the dynamics of slow-roll inflation that consistently incorporates quantum corrections, based on an alternative functional renormalisation group (RG) approach. We derive the coupled Friedmann-RG flow equations governing the joint evolution of spacetime, the inflaton field, and its effective potential. Applying this formalism to $\alpha$-attractor E-models, we find that the RG flow induces a dynamical destabilisation of the inflationary trajectory, leading to a premature termination of slow roll. Remarkably, the resulting predictions bring $\alpha$-attractors into full agreement with the latest ACT data without introducing new physics beyond a consistent quantum-corrected treatment of the inflaton dynamics.

    ↳ hep-thastro-ph.COgr-qchep-ph15 citations
19. 19*

    Quantum Gravity, de Sitter Space, and Normalizability

    Stephon Alexander🇺🇸 · Heliudson Bernardo🇨🇦 · Jacob Kuntzleman🇺🇸 · Max Pezzelle🇺🇸

    We propose a resolution to the longstanding problem of perturbative normalizability in canonical quantum gravity of the Lorentzian Chern-Simons-Kodama (CSK) state with a positive cosmological constant in four dimensions. While the CSK state is an exact solution to the Hamiltonian constraint in the self-dual formulation and semiclassically describes de Sitter spacetime, its physical viability has been questioned due to apparent nonnormalizability and CPT asymmetry. Starting from a nonperturbative holomorphic inner product derived from the reality conditions of the self-dual Ashtekar variables, we show that the linearization, in terms of gravitons, of the CSK state is perturbatively normalizable for super-Planckian cosmological constant. Furthermore, we demonstrate that a rotation in phase space, a generalization of Thiemann's complexifier, can render the full perturbative state normalizable for all $\Lambda$ by analytically continuing the non-convergent modes in phase space. This provides the first concrete realization of a CPT-breaking, yet normalizable, gravitational vacuum state rooted in a nonperturbative quantum gravity framework. Our results establish the CSK state-long thought formal-as a viable candidate for the ground state of quantum gravity in de Sitter space.

    ↳ hep-thastro-ph.COgr-qchep-phClass.Quant.Grav.(2026)·3 citations
20. 20*

    Quantum-corrected gravitational collapse and multi-messenger signatures: Beyond spherical symmetry in loop quantum gravity

    Hoang Van Quyet🇻🇳

    We present a comprehensive theoretical framework for multi-messenger signatures arising from quantum-corrected gravitational collapse within an extended Ashtekar-Olmedo-Singh (AOS) loop quantum gravity model incorporating perturbative asymmetries. By developing a consistent perturbation theory for non-spherical modes on the quantum-corrected spherically symmetric background, we resolve the fundamental tension between spherical symmetry assumptions and gravitational wave emission requirements. Our analysis demonstrates that quantum geometric effects naturally seed asymmetric perturbations during the bounce phase, leading to observable gravitational wave bursts with mass-dependent frequencies in the range $f_{\mathrm{gw}}\sim 10^{-3}$--$10^3$ Hz and distinctive electromagnetic counterparts via quantum field effects in curved spacetime. Through self-consistent calculations based on the effective AOS framework, we compute the coupling between quantum bounce dynamics and perturbative modes, yielding gravitational wave strains $h\sim 10^{-23}$--$10^{-21}$ at 100 Mpc for primordial black holes with masses $M\sim 1$--$100$ $M_{\odot }$. The electromagnetic emission mechanism is analyzed through detailed calculations of dynamic Casimir effects and coherent field amplification in time-dependent quantum geometry. Our parameter sensitivity analysis reveals detection prospects that are critically dependent on primordial black hole abundance constraints, with realistic event rates of $\text{mc}R\sim 10^{-3}$--$10^{-1}$ yr${}^{-1}$ within current observational limits. These results provide testable predictions for quantum gravity theories while extending previous work beyond spherical symmetry assumptions.

    ↳ gr-qchep-ph0 citations
21. 21*

    Opportunities for Imaging Light Nuclei with a Second Interaction Region at the Electron-Ion Collider

    Wan Chang🇨🇳 · Elke-Caroline Aschenauer🇺🇸 · Alexander Jentsch🇺🇸 · Arjun Kumar🇺🇸 · Zhoudunming Tu🇺🇸 · Zhongbao Yin🇨🇳

    The upcoming Electron-Ion Collider (EIC) will address several outstanding puzzles in modern nuclear physics. Key questions-such as the partonic structure of nucleons and nuclei and the origin of their mass and spin-can be explored through high-energy electron-proton and electron-nucleus collisions. To maximize its scientific reach, the EIC community has advocated for the addition of a second interaction region equipped with a detector complementary to the EIC general purpose collider detector, ePIC. The pre-conceptual design of this interaction region aims to provide a different configuration from the first interaction region, which enhances forward acceptance at very small scattering angles ($\theta \sim 0$ mrad). This machine configuration would significantly benefit exclusive, tagging, and diffractive physics programs, complementing those of the ePIC experiment. In particular, accessing coherent diffractive processes on light nuclei by tagging of the full, intact nucleus is essential for mapping their spatial parton distributions. In this work, we present an exploratory study of the detection capabilities for light nuclei at a second EIC interaction region, with a detailed discussion of the accessible kinematic phase space and its implications for imaging.

    ↳ nucl-exhep-exhep-phPRD(2026)·2 citations
22. 22*

    Two-body Dirac equation in DSR: results for fermion-antifermion pairs

    Nosratollah Jafari🇰🇿 · Abdullah Guvendi🇹🇷

    This study investigates a modified two-body Dirac equation in (2+1)-dimensional spacetime, inspired by Amelino-Camelia's doubly special relativity (DSR). We begin by deriving a covariant two-body Dirac equation that, in the absence of DSR modifications, reduces to a Bessel-type wave equation. Incorporating corrections from the chosen DSR model modifies this wave equation, yielding solutions consistent with established results in the low-energy regime. We demonstrate that the effects of DSR modifications become particularly pronounced at large relative distances. For a coupled fermion-antifermion pair, we derive the modified binding energy solutions. By accounting for first-order Planck-scale corrections, we show that the fine-structure constant \alpha behaves as an energy-dependent running parameter, given by \(\alpha_{eff(E)}/\alpha \approx 1 - \frac{E}{4E_p}\), where E_p is the Planck energy. Binding energy levels are computed using a first-order approximation of the DSR modifications, and the results are applied to positronium-like systems. Our model reveals that DSR modifications induce shifts in the binding energy levels. To the best of our knowledge, DSR-modified two-body equations have not been previously studied. This model is the first of its kind, opening new avenues for further research in this area.

    ↳ gr-qchep-phhep-thPLB(2025)·8 citations
23. 23*

    Generalised anomalies, QCD${}_4$, and holography

    Mohammad Akhond🇯🇵 · Shigeki Sugimoto🇯🇵

    During the last decade, the notion of an 't Hooft anomaly has been generalised to the case of discrete symmetries. An interesting instance, discussed by Tanizaki, is the mixed anomaly between the discrete axial symmetry and the flavour and baryonic symmetries in massless QCD${}_4$. The goal of this note is to provide a derivation of this anomaly from a top-down holographic dual of QCD${}_4$. It is found that the topological couplings in the bulk supergravity dual of the D4-D8 system encode Tanizaki's anomaly, once fluctuations around the bulk gauge fields are turned on. A technical challenge for this computation is the difficulty in maintaining gauge invariance of supergravity theories in the presence of D-branes. To overcome this issue, a compact formulation of the flux sector of (massive) type IIA supergravity in the presence of D8 branes is presented. A crucial ingredient in the analysis is the need for smearing the D8 branes, in order to impose $\tau$-shift invariance on the fluctuation ansatz.

    ↳ hep-thhep-ph2 citations
24. 24*

    Probing Dark Energy Microphysics with kSZ Tomography

    Julius Adolff🇨🇦 · Selim Hotinli🇨🇦 · Neal Dalal🇨🇦

    The accelerated expansion of the Universe is well established by geometric probes, yet its physical origin remains poorly understood. Most constraints on dark energy arise from background observables -- supernovae, baryon acoustic oscillations, and the cosmic microwave background -- which mainly test the homogeneous expansion history. To move beyond this limitation, we examine how kinetic Sunyaev--Zel'dovich (kSZ) tomography, combined with galaxy clustering, can probe perturbative effects of dark energy and improve constraints on its background parameters. Using a Fisher-matrix analysis of the joint power spectra for LSST- and CMB-S4-like surveys, we quantify the additional information kSZ tomography contributes to dark-energy inference. Including kSZ data tightens constraints on $w_0$ by 15 % and on $w_a$ by 32 %, with parameter degeneracies distinct from those of geometric probes. We also assess the detectability of dark-energy perturbations through a two-parameter model, finding that for canonical sound speed ($c_s=1$) the effects are sub-percent and confined to horizon scales, while smaller sound speeds shift them to accessible $k$-ranges. Near-term kSZ measurements will primarily serve to test the consistency between background and perturbative signals, while future low-noise, high-resolution surveys may begin to uncover the microphysical properties of dark energy.

    ↳ astro-ph.COhep-ph3 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.