Fri·Nov 15, 2024Friday·November 15, 2024

1. 01*

   Invisible decays of vector Charmonia and Bottomonia to determine the Weak Mixing Angle at quarkonia scale

   G. Hernández-Tomé🇲🇽 · C. S. Kim🇰🇷 · G. López Castro🇲🇽

   We compute the branching fractions of vector quarkonia ($V_Q=J/\psi ,{\psi }^{\prime },{\rm Y}(nS)$) decays into neutrino pairs, considering both Dirac and Majorana types, within the Standard Model (SM) and beyond. The vector nature of quarkonium states yields a decay width in the SM that depends upon the weak vector coupling of the heavy quark, offering the possibility to measure the weak mixing angle at the quarkonia mass scales. If neutrinos have non-standard neutral weak couplings, this could help to distinguish the nature of neutrinos in principle.

   hep-phEPJC(2025)·2 citations
2. 02*

   Enhancing generalization in high energy physics using white-box adversarial attacks

   Franck Rothen🇨🇭 · Samuel Klein🇨🇭 · Matthew Leigh🇨🇭 · Tobias Golling🇨🇭

   Machine learning is becoming increasingly popular in the context of particle physics. Supervised learning, which uses labeled Monte Carlo (MC) simulations, remains one of the most widely used methods for discriminating signals beyond the Standard Model. However, this paper suggests that supervised models may depend excessively on artifacts and approximations from Monte Carlo simulations, potentially limiting their ability to generalize well to real data. This study aims to enhance the generalization properties of supervised models by reducing the sharpness of local minima. It reviews the application of four distinct white-box adversarial attacks in the context of classifying Higgs boson decay signals. The attacks are divided into weight-space attacks and feature-space attacks. To study and quantify the sharpness of different local minima, this paper presents two analysis methods: gradient ascent and reduced Hessian eigenvalue analysis. The results show that white-box adversarial attacks significantly improve generalization performance, albeit with increased computational complexity.

   hep-phcs.LGPRD(2025)·1 citation
3. 03*

   Magnetic dipole moments of the singly-heavy baryons with spin-$\frac{1}{2}$ and spin-$\frac{3}{2}$

   U. Özdem🇹🇷

   The electromagnetic characteristics of singly-heavy baryons at low energies are responsive to their internal composition, structural configuration, and the associated chiral dynamics of light diquarks. To gain further insight, experimentalists are attempting to measure the magnetic and electric dipole moments of charm baryons at the LHC. In view of these developments, we conducted an extensive analysis of the magnetic dipole moments of both ${\mathrm{J}}^{\mathrm{P}}={\frac{1}{2}}^{+}$ and ${\mathrm{J}}^{\mathrm{P}}={\frac{3}{2}}^{+}$ singly-heavy baryons by means of the QCD light-cone sum rules. Our findings have been compared with other phenomenological estimations that could prove a valuable supplementary resource for interpreting the singly-heavy baryon sector. To shed light on the internal structure of these baryons we study the contributions of the individual quark sectors to the magnetic dipole moments. It was observed that the magnetic dipole moments of the spin-$\frac{1}{2}$ sextet singly-heavy baryons are governed by the light quarks. Conversely, the role of the heavy quark is significantly enhanced for the spin-$\frac{1}{2}$ anti-triplet and spin-$\frac{3}{2}$ sextet singly-heavy baryons. The contribution of light and heavy quarks is observed to have an inverse relationship. The signs of the magnetic dipole moments demonstrate the interaction of the spin degrees of freedom of the quarks. The opposing signs of the light and heavy-quark magnetic dipole moments imply that the spins of these quarks are anti-aligned with respect to each other in the baryon. As a byproduct, the electric quadrupole and magnetic octupole moments of spin-$\frac{3}{2}$ singly-heavy baryons are also calculated. We ascertained the existence of non-zero values for the electric quadrupole and magnetic octupole moments of these baryons, indicative of a non-spherical charge distribution.

   hep-phhep-exhep-latEPJA(2025)·8 citations
4. 04*

   New physics searches via angular distributions of $\bar{B}\to D^{\ast }(\to D\pi )\tau (\to \ell {\nu }_{\tau }{\bar{\nu }}_{\ell }){\bar{\nu }}_{\tau }$ decays

   Bhubanjyoti Bhattacharya🇺🇸 · Thomas E. Browder🇺🇸 · Alakabha Datta🇺🇸 · Tejhas Kapoor🇫🇷 · Emi Kou🇫🇷 · Lopamudra Mukherjee🇨🇳

   The study of $\bar{B}\to D^{\ast }\tau {\bar{\nu }}_{\tau }$ angular distribution can be used to obtain information about new physics (or beyond the Standard Model) couplings, which are motivated by various $B$ anomalies. However, the inability to measure precisely the three-momentum of the $\tau$ lepton hinders such measurements, as the tau decay contains one or more undetected neutrinos. Here, we present a measurable angular distribution of $\bar{B}\to D^{\ast }\tau {\bar{\nu }}_{\tau }$ by considering the additional decay $\tau \to \ell {\nu }_{\tau }{\bar{\nu }}_{\ell }$, where $\ell \in \{e,\mu \}$. The full process used is $\bar{B}\to D^{\ast }(\to D\pi )\tau (\to \ell {\nu }_{\tau }{\bar{\nu }}_{\ell }){\bar{\nu }}_{\tau }$, in which only the $\ell$ and $D^{\ast }$ are reconstructed. A fit to the experimental angular distribution of this process can be used to extract information on new physics parameters. To demonstrate the feasibility of this approach, we generate simulated data for this process and perform a sensitivity study to obtain the expected statistical errors on new physics parameters from experiments in the near future. We obtain a sensitivity of the order of 5% for the right-handed current and around 6% for the tensor current. In addition, we use the recent lattice QCD data on $B\to D^{\ast }$ form factors and obtain correlations between form factors and new physics parameters.

   hep-phhep-exJHEP(2025)·5 citations
5. 05*

   Simulation of the process $e^{+}{e}^{-}\to W^{+}{W}^{-}$ with the heavy right-handed neutrino exchange at 1 TeV future lepton colliders

   A. Drutskoy🇷🇺 · E. Vasenin🇷🇺

   We study potential contribution of the heavy right-handed neutrino exchange in the process $e^{+}{e}^{-}\to W^{+}{W}^{-}$. This process is sensitive to heavy neutrinos with masses larger than $\sqrt{s}$. The Monte Carlo simulation of the studied process is performed assuming the Seesaw type-I model, where heavy right-handed neutrinos (heavy neutral leptons, HNL) are introduced in the leptonic sector. Within the Standard Model (SM), the process has a large cross section described by diagrams with $s$-channel $Z/\gamma$ exchange and $t$-channel active neutrino exchange. Respectively, the $t$-channel right-handed neutrino exchange amplitude will interfere with these SM amplitudes. However, the angular distributions of the $W$ boson production and decay are different for the right-handed neutrino and SM amplitudes. That can be used to evaluate potential HNL contribution using the extended likelihood method. The simulation of the $e^{+}{e}^{-}\to W^{+}{W}^{-}$ process is performed at the 1 TeV center-of-mass energy and polarisation $P_{e^{+}{e}^{-}}$ of (20 %, -80 %), which is a standard option for the future linear $e^{+}{e}^{-}$ collider ILC. Both $W$ bosons are reconstructed from two hadronic jets. Simulation of the SM background processes is also done. The beam-induced backgrounds and the initial state radiation (ISR) effects are taken into account. The majority of background processes are effectively suppressed by the cuts on the invariant masses of two and four jets. Finally, we obtain upper limits on the mixing parameter $|V_{eN}{|}^2$ as a function of $M(N)$.

   hep-phhep-exPRD(2025)·2 citations
6. 06*

   The Three-Point Energy Correlator in the Coplanar Limit

   Anjie Gao🇺🇸 · Tong-Zhi Yang🇨🇭 · Xiaoyuan Zhang🇺🇸

   Energy correlators are a type of observables that measure how energy is distributed across multiple detectors as a function of the angles between pairs of detectors. In this paper, we study the three-point energy correlator (EEEC) at lepton colliders in the three-particle near-to-plane (coplanar) limit. The leading-power contribution in this limit is governed by the three-jet (trijet) configuration. We introduce a new approach by projecting the EEEC onto the volume of the parallelepiped formed by the unit vectors aligned with three detected final-state particles. Analogous to the back-to-back limit of the two-point energy correlator probing the dijet configuration, the small-volume limit of the EEEC probes the trijet configuration. We derive a transverse momentum dependent (TMD) based factorization theorem that captures the soft and collinear logarithms in the coplanar limit, which enables us to achieve the next-to-next-to-next-to-leading logarithm (N${}^3$LL) resummation. To our knowledge, this is the first N${}^3$LL result for a trijet event shape. Additionally, we demonstrate that a similar factorization theorem can be applied to the fully differential EEEC in the three-particle coplanar limit, which provides a clean environment for studying different coplanar trijet shapes.

   hep-phhep-exnucl-thJHEP(2025)·13 citations
7. 07*

   Towards a Global Analysis of the $b\to c\bar{u}q$ Puzzle

   Stefan Meiser🇪🇸 · Danny van Dyk🇬🇧 · Javier Virto🇪🇸

   We study the nonleptonic decays ${\bar{B}}_s^0\to D_s^{(\ast )+}{\pi }^{-}$ and ${\bar{B}}^0\to D^{(\ast )+}{K}^{-}$ within the Weak Effective Theory (WET) up to mass-dimension six. We revisit the calculation of the hadronic matrix elements within QCD Factorization including the full set of WET operators. We recalculate the two-particle contributions to the hard-scattering kernels at next-to-leading order in ${\alpha }_s$, confirming recent results in the literature. We also calculate the three-particle contributions at leading order in ${\alpha }_s$, clarifying the procedure, refining the SM results in the literature, and providing for the first time the complete set of contributions within the WET. We use these results to perform a global phenomenological study of the effective couplings, putting bounds on the size of the WET Wilson coefficients in four distinct fit models. The fits include constraints from the nonleptonic $B$-meson decay width, which we calculate at the leading order for the full set of WET operators for the first time. This study is the first one to account for simultaneous variation of up to six effective couplings. We identify two distinct modes in all fit models and discuss how future measurements can be used to distinguish between them.

   hep-phJHEP(2025)·12 citations
8. 08*

   Collider fingerprints of freeze-in dark matter produced during the fast expansion phase of Universe

   Anupam Ghosh🇮🇳 · Partha Konar🇮🇳 · Sudipta Show🇮🇳

   We examine a simple dark sector extension where the observed dark matter (DM) abundance arises from a freeze-in process through the decay of heavy vector-like quarks into a scalar dark matter candidate. The detection prospects of such DM are challenging due to the feeble nature of the interactions, but these vector-like quarks can be produced copiously at the LHC, where they decay to Standard Model quarks along with DM. Depending on the decay rate, this scenario is typically probed through long-lived particle or displaced vertex signatures, assuming a radiation-dominated background. An alternative hypothesis suggests that the Universe may have experienced a rapid expansion phase instead of the standard radiation-dominated one during freeze-in. This would significantly alter the dark matter phenomenology, requiring a substantial increase in the interaction rate to match the observed relic density, resulting in the rapid decay of the parent particle. As a result, much of the parameter space for this scenario is beyond the reach of traditional long-lived particle and displaced vertex searches. Due to this non-standard cosmic evolution, existing constraints do not cover the expanded dark matter parameter space. We propose a complementary search strategy to explore this scenario, offering additional limits alongside searches for long-lived particles and displaced vertices. In our search, we investigate the FIMP dark matter model at the LHC using boosted fatjets and significant missing transverse momentum. To improve precision, we include one-loop QCD corrections for LHC production processes and employ a boosted decision tree multivariate analysis, leveraging jet substructure variables to explore a vast parameter space for this minimally extended FIMP dark matter model at the 14 TeV LHC.

   hep-phPRD(2025)·10 citations
9. 09*

   A ${\mathbb{CP}}^2$ SMEFT

   N. S. Manton🇬🇧

   An extension of the Standard Model is proposed, where the Higgs field is valued in the complex projective plane ${\mathbb{CP}}^2$, rather than ${\mathbb{C}}^2$. Its geometry is consistent with $U(2)\simeq (SU(2)\times U(1))/{\mathbb{Z}}_2$ electroweak gauge symmetry. The leading terms in the Lagrangian, beyond those of the Standard Model, are much more tightly constrained than in general SMEFTs, and the custodial $SO(4)$ symmetry of the Higgs sector is mildly broken. The predicted tree-level deviations from Standard Model phenomenology depend on a single large mass parameter $M$. Current experimental data imply that $M$ is a few TeV or larger.

   hep-phhep-thJHEP(2025)·3 citations
10. 10*

    The strong CP puzzle and axions

    Christopher Smith🇫🇷

    In the first part of this talk, after a brief presentation of the strong CP puzzle, the construction of axion models and their main phenomenological features are described. In the second part, the possibility to mix the Peccei-Quinn symmetry with baryon and lepton numbers is discussed, showing that the axion could ultimately play a role in other puzzles of the Standard Model like the smallness of neutrino masses or baryogenesis.

    hep-phPoS(2025)·4 citations
11. 11*

    Constraints on the hadronic light-by-light tensor in corner kinematics for the muon $g-2$

    Johan Bijnens🇸🇪 · Nils Hermansson-Truedsson🇬🇧 · Antonio Rodríguez-Sánchez🇪🇸

    The dispersive approach to the hadronic light-by-light contribution to the muon $g-2$ involves an integral over three virtual photon momenta appearing in the light-by-light tensor. Building upon previous works, we systematically derive short-distance constraints in the region where two momenta are large compared to the third, the so-called Melnikov-Vainshtein or corner region. We include gluonic corrections for the different scalar functions appearing in the Lorentz decomposition of the underlying tensor, and explicitly check analytic agreement with alternative operator product expansions in overlapping regimes of validity. A very strong pattern of cancellations is observed for the final $g-2$ integrand. The last observation suggests that a very compact expression only containing the axial current form factors can provide a good approximation of the corner region of the hadronic light-by-light tensor.

    hep-phJHEP(2025)·48 citations
12. 12*

    One or two poles for the $\Xi (1820)$?

    R. Molina🇪🇸 · Wei-Hong Liang🇨🇳 · Chu-Wen Xiao🇨🇳 · Zhi-Feng Sun🇨🇳 · E. Oset🇪🇸

    In this talk, we present a new interpretation for the recently observed $\Xi (1820)$ resonance. We recall that the chiral unitary approach for the interaction of pseudoscalar mesons with the baryons of the decuplet predicts two states for the $\Xi (1820)$ resonance, one with a narrow width and the other one with a large width. We contrast this fact with the recent BESIII measurement of the $K^{-}\Lambda$ mass distribution in the $\psi (3686)$ decay to $K^{-}\Lambda {\bar{\Xi }}^{+}$, which demands a width much larger than the average of the PDG, and show how the consideration of the two $\Xi (1820)$ states provides a natural explanation to this apparent contradiction.

    hep-phPoS(2025)·1 citation
13. 13*

    Study of large extra dimension and neutrino decay at P2SO experiment

    Papia Panda🇮🇳 · Priya Mishra🇮🇳 · Samiran Roy🇮🇳 · Monojit Ghosh🇭🇷 · Rukmani Mohanta🇮🇳

    In this study, we explore two intriguing new physics scenarios: the theory of Large Extra Dimensions (LED) and the theory of neutrino decay. We analyze the impact of LED on neutrino oscillations in the contexts of Protvino to Super-ORCA (P2SO), DUNE, and T2HK, with a particular emphasis on P2SO. In contrast, the effects of neutrino decay are examined exclusively in the context of P2SO. For the LED scenario, we find that combining data from P2SO, DUNE, and T2HK can yield tighter constraints than current bounds, but only if all oscillation parameters are measured with high precision. In the case of neutrino decay, P2SO can achieve slightly better bounds compared to ESSnuSB and MOMENT, although its bounds remain weaker than those provided by DUNE and T2HK. Regarding sensitivities to unresolved oscillation parameters, the existence of LED has a minimal impact on the determination of CP violation, mass ordering and octant. However, neutrino decay can significantly influence the sensitivities related to CP violation and octant in a non-trivial manner.

    hep-phJHEP(2025)·6 citations
14. 14*

    A unified description of small, peripheral, and large system suppression data from pQCD

    Coleridge Faraday🇿🇦 · W. A. Horowitz🇿🇦

    We present quantitative predictions for the nuclear modification factor in both small and peripheral systems from a pQCD-based energy loss model that is constrained by light- and heavy-flavor suppression data from central heavy-ion collisions. We find nearly identical suppression for central $p/d+A$ collisions as for peripheral $A+A$ collisions, quantitatively consistent with the measured 20% suppression of neutral pions produced in $d+\mathrm{Au}$ collisions by PHENIX, but dramatically inconsistent with the measured 20% enhancement of charged hadrons produced in $p+\mathrm{Pb}$ collisions by ATLAS. We demonstrate that this equivalence of central small system suppression and peripheral large system suppression is insensitive to the underlying energy loss model.

    hep-phnucl-thPLB(2025)·9 citations
15. 15*

    Revisiting the LHC Constraints on Gauge-Mediated Supersymmetry Breaking Scenarios

    Kirtiman Ghosh🇮🇳 · Katri Huitu🇫🇮 · Rameswar Sahu🇮🇳

    Supersymmetry (SUSY) addresses several problems of the Standard Model, such as the naturalness problem and gauge coupling unification, and can provide cosmologically viable dark matter candidates. SUSY must be broken at high energy scales with mechanisms like gravity, anomaly, gauge mediation, etc. This paper revisits the Gauge Mediated SUSY Breaking (GMSB) scenarios in the context of data from the Large Hadron Collider (LHC) experiment. The ATLAS mono-photon search at 139 inverse femtobarn integrated luminosity at the 13 TeV LHC, in the context of a simplified General Gauge Mediation (GGM) scenario (which is a phenomenological version of GMSB with an agnostic approach to the nature of the hidden sector), relies on assumptions that do not hold across the entire parameter space. We identify a few crucial assumptions regarding the decay widths of SUSY particles into final states with gravitinos that affect the LHC limits on the masses of the SUSY particles. Our study aims to reinterpret the ATLAS constraints on the gluino-NLSP mass plane, considering all possible decay modes of SUSY particles in a realistic GGM model.

    hep-phPRD(2025)·1 citation
16. 16*

    Effect of invisible neutrino decay on neutrino oscillation at long baselines

    Animesh Chatterjee🇨🇭 · Srubabati Goswami🇮🇳 · Supriya Pan🇮🇳 · Paras Thacker🇮🇳

    In this article, we study the effect of invisible neutrino decay of the third neutrino state for accelerator neutrino experiments at two different baselines, 1300 km with a liquid argon time projection chamber (LArTPC) detector (similar to DUNE) and 2588 km with a water Cherenkov detector (similar to P2O). For such baselines, the matter effect starts to become important. Our aim is to ascertain the sensitivity to mass hierarchy and octant of ${\theta }_{23}$ in these two experiments in the presence of a decaying neutrino state. We compare and contrast the results of the two experimental setups. We find that, in general, hierarchy sensitivity decreases in the presence of decay. However, if we consider decay only in the opposite hierarchy (test scenario), in the 2588 km setup, the hierarchy sensitivity with the true hierarchy as IH is larger than the no decay case. We also study the dependence of hierarchy sensitivity with true ${\theta }_{23}$. We find that the dominant muon background in P2O plays an important role in how the hierarchy sensitivity depends on ${\theta }_{23}$. The octant sensitivity for both setups increases in the presence of decay except for the LArTPC setup in case true ${\theta }_{23}=49^{\circ }$. To understand the octant sensitivity results in the two setups, we check the synergy in sensitivity between electron and muon channels as a function of test ${\theta }_{23}$. We also study the degeneracies in the test ${\theta }_{23}-{\delta }_{CP}$ plane and find that combined analysis of the two setups removes all the degeneracies in the test ${\theta }_{23}-{\delta }_{CP}$ plane at $5\sigma$ significance.

    hep-phnucl-th1 citation
17. 17*

    Open $B$-hadron production at hadron colliders in QCD at next-to-next-to-leading-order and next-to-next-to-leading-logarithmic accuracy

    Michał Czakon🇩🇪 · Terry Generet🇬🇧 · Alexander Mitov🇬🇧 · Rene Poncelet🇵🇱

    We report on a calculation of open heavy-flavor production at hadron colliders which extends to next-to-next-to-leading order (NNLO) accuracy the classic NLO-accurate formalism developed almost 30 years ago under the acronym FONLL. The approach retains the exact heavy-flavor mass dependence at low transverse momentum, $p_T$, and resums collinear logarithms through next-to-next-to-leading log (NNLL) at high $p_T$. Provided are predictions for $B$-hadrons as well as $B$-decay products like $J/\Psi$ and muons. The main features of the NNLO+NNLL results are reduced scale dependence and moderate NNLO correction, consistent with perturbative convergence in a wide range of kinematic scales from few GeV up to asymptotically large values of $p_T$. The new calculation significantly improves the agreement with data for $B$-hadrons and muons. We uncover an intriguing discrepancy in $J/\Psi$ final states which may point to a lower value of the $B\to J/\Psi$ decay rate.

    hep-phhep-exPRL(2025)·17 citations
18. 18*

    Reggeization in Color

    Anjie Gao🇺🇸 · Ian Moult🇺🇸 · Sanjay Raman🇺🇸 · Gregory Ridgway🇺🇸 · Iain W. Stewart🇺🇸

    In the high energy limit, $s\gg -t$, amplitudes in planar gauge theories Reggeize, with power law behavior $(\frac{s}{-t}{)}^{\alpha (t)}$ governed by the Regge trajectory $\alpha (t)$. Beyond the planar limit this simplicity is violated by "Regge cuts", for which practical organizational principles are still being developed. We use a top-down effective field theory organization based on color projection in the $t$ channel and rapidity evolution equations for collinear impact factors, to sum large $s\gg -t$ logarithms for Regge cut contributions. The results are matrix equations which are closed within a given color channel. To illustrate the method we derive in QCD with $SU(N_c)$ for the first time a closed 6$\times$6 evolution equation for the "decupletons" in the $\text{10}\oplus \overline{\text{10}}$ Regge color channel, a 2$\times$2 evolution equation for the "triantapentons" in the $\text{35}\oplus \overline{\text{35}}$ color channel, and a scalar evolution equation for the "tetrahexaconton" in the 64 color channel. More broadly, our approach allows us to describe generic Reggeization phenomena in non-planar gauge theories, providing valuable data for the all loop structure of amplitudes beyond the planar limit.

    hep-phhep-thnucl-th8 citations
19. 19*

    Hadronic light-by-light scattering contribution to 1S-2S transition in muonium

    V. I. Korobov🇷🇺 · F. A. Martynenko🇷🇺 · A. P. Martynenko🇷🇺 · A. V. Eskin🇷🇺

    We study hadronic light-by-light scattering contribution to the energy interval (1S-2S) in muonium. Various amplitudes of interaction of a muon and an electron are constructed, in which the effect of hadronic scattering of light-by-light is determined using the transition form factor of two photons into a meson. Their contributions to the particle interaction operator in the case of S-states are obtained in integral form, and to the energy spectrum in numerical form. The contributions of pseudoscalar, scalar, axial vector mesons are taken into account.

    hep-phphysics.atom-phPRC(2025)·3 citations
20. 20*

    Equation of State of Decompressed Quark Matter, and Observational Signatures of Quark-Star Mergers

    Zhiqiang Miao🇨🇳 · Zhenyu Zhu🇺🇸 · Dong Lai🇨🇳

    Quark stars are challenging to confirm or exclude observationally because they can have similar masses and radii as neutron stars. By performing the first calculation of the non-equilibrium equation of state of decompressed quark matter at finite temperature, we determine the properties of the ejecta from binary quark-star or quark star-black hole mergers. We account for all relevant physical processes during the ejecta evolution, including quark nugget evaporation and cooling, and weak interactions. We find that these merger ejecta can differ significantly from those in neutron star mergers, depending on the binding energy of quark matter. For relatively high binding energies, quark star mergers are unlikely to produce r-process elements and kilonova signals. We propose that future observations of binary mergers and kilonovae could impose stringent constraints on the binding energy of quark matter and the existence of quark stars.

    ↳ astro-ph.HEhep-phnucl-thPRL(2025)·11 citations
21. 21*

    Classical Observables from Causal Response Functions

    Shovon Biswas🇨🇦 · Julio Parra-Martinez🇫🇷

    We revisit the calculation of classical observables from causal response functions, following up on recent work by Caron-Huot at al. [JHEP 01 (2024) 139]. We derive a formula to compute asymptotic in-in observables from a particular soft limit of five-point amputated response functions. Using such formula, we re-derive the formulas by Kosower, Maybee and O'Connell (KMOC) for the linear impulse and radiated linear momentum of particles undergoing scattering, and we present an unambiguous calculation of the radiated angular momentum at leading order. Then, we explore the consequences of manifestly causal Feynman rules in the calculation of classical observables by employing the causal (Keldysh) basis in the in-in formalism. We compute the linear impulse, radiated waveform and its variance at leading and/or next-to-leading order in the causal basis, and find that all terms singular in the $\hslash \to 0$ limit cancel manifestly at the integrand level. We also find that the calculations simplify considerably and classical properties such as factorization of six-point amplitudes are more transparent in the causal basis.

    ↳ hep-thgr-qchep-phJHEP(2025)·12 citations
22. 22*

    Excess Radiation from Axion-Photon Conversion

    Andrea Addazi🇨🇳 · Salvatore Capozziello🇮🇹 · Qingyu Gan🇮🇹 · Gaetano Lambiase🇮🇹 · Rome Samanta🇮🇹

    Two notable anomalies in radio observations -- the excess radiation in the Rayleigh-Jeans tail of the cosmic microwave background, revealed by ARCADE2, and the twice-deeper absorption trough of the global 21cm line, identified by EDGES -- remain unresolved. These phenomena may have a shared origin, as the enhancement of the 21cm absorption trough could arise from excess heating. We investigate this scenario through the framework of axion-like particles (ALPs), showing that the resonant conversion of ALPs into photons can produce a photon abundance sufficient to resolve both anomalies simultaneously. Our model naturally explains the observed radio excess between 0.4 and 10GHz while also enhances the 21cm absorption feature at 78MHz. Furthermore, it predicts a novel power-law scaling of the radio spectrum above 0.5GHz and an additional absorption trough below 30MHz, which could be verified through cross-detection in upcoming experiments.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2025)·7 citations
23. 23*

    Geminga: A Window into the Role Played by the Local Halo in the Cosmic-Ray Propagation Process

    Lin Nie🇨🇳 · Yu-Hai Ge🇨🇳 · Yi-Qing Guo🇨🇳 · Si-Ming Liu🇨🇳

    A novel phenomenon among the recently observed Geminga pulsar halo is the presence of distinct radiation morphology at high energies, while no extended radiation is detected in the 10-500 GeV energy band within a $40°\times 40°$ region. This phenomenon suggests that pulsar halos play a crucial role in the local propagation of cosmic rays, making it necessary to investigate the underlying mechanisms of this phenomenon. This work focuses on the 3D propagation study of cosmic rays, incorporating the Geminga pulsar into our propagation framework to investigate its contribution to different observational spectra. We consider Geminga a dominant local source of positrons, partially reproducing the observed positron spectrum and multi-wavelength radiative spectra of the Geminga halo. Through calculations of signal and background at different angles, we find that: (1) The slow-diffusion properties near the Geminga pulsar and its proper motion may cause the radiation from electrons originating from Geminga to be distributed across a more extended region. (2) The incomplete subtraction of radiation from the local halo may contribute, to some extent, to the diffuse gamma ray fluctuations detected by LHAASO. We hope that LHAASO will detect more sources of cosmic ray halo to further validate our model.

    ↳ astro-ph.HEhep-phApJ(2025)·2 citations
24. 24*

    On the consistency of Lorentz-Violating Yang-Mills theories: Gauge invariance and non-perturbative effects

    Antonio D. Pereira🇧🇷

    Previous investigations on the renormalizability properties of Lorentz-violating Yang-Mills (LVYM) theories in the Landau gauge have pointed out the necessity of the inclusion of a mass-like term for the gauge fields. If one aims at generalizing the theory to a more complicated gauge, such a mass-like term can bring severe issues regarding gauge-dependence of correlation functions of observables. We propose a Lorentz-violating Yang-Mills theory supplemented by a gauge-invariant mass term which generalizes the model in the Landau gauge. We discuss the foundational aspects of the model and highlight how it simplifies in the Landau gauge. Following the recent literature in pure Yang-Mills theories, we remark how the proposed massive extension of LVYM theories can be used as an effective model to access infrared properties within perturbation theory. Finally, we present a BRST-invariant formulation of the so-called Refined Gribov-Zwanziger action in the presence of Lorentz-violating terms in linear covariant gauges and the underlying tree-level gauge-field propagator which is enriched by the non-perturbative information carried by the elimination of Gribov copies.

    ↳ hep-thhep-phPRD(2024)·0 citations
25. 25*

    An Improved Bound on Nonlinear Quantum Mechanics using a Cryogenic Radio Frequency Experiment

    Oleksandr Melnychuk🇺🇸 · Bianca Giaccone🇺🇸 · Nicholas Bornman🇺🇸 · Raphael Cervantes🇺🇸 · Anna Grassellino🇺🇸 · Roni Harnik🇺🇸 · David E.Kaplan🇺🇸 · Geev Nahal🇺🇸 · Roman Pilipenko🇺🇸 · Sam Posen🇺🇸 · Surjeet Rajendran🇺🇸 · Alexander O. Sushkov🇺🇸

    There are strong arguments that quantum mechanics may be nonlinear in its dynamics. A discovery of nonlinearity would hint at a novel understanding of the interplay between gravity and quantum field theory, for example. As such, experiments searching for potential nonlinear effects in the electromagnetic sector are important. Here we outline such an experiment, consisting of a stream of random bits (which were generated using Rigetti's Aspen-M-3 chip) as input to an RF signal generator coupled to a cryogenic detector. Projective measurements of the qubit state, which is originally prepared in an equal superposition, serve as the random binary output of a signal generator. Thereafter, spectral analysis of the RF detector would yield a detectable excess signal predicted to arise from such a nonlinear effect. A comparison between the projective measurements of the quantum bits vs the classical baseline showed no power excess. This sets a new limit on the electromagnetic nonlinearity parameter $|ϵ|⪅1.15\times 10^{-12}$, at a 90.0% confidence level. This is the most stringent limit on nonlinear quantum mechanics thus far and an improvement by nearly a factor of 50 over the previous experimental limit.

    ↳ quant-phgr-qchep-phphysics.ins-detPRD(2025)·2 citations
26. 26*

    The lowest-radiation environments in the Solar System: new opportunities for underground rare-event searches

    Xilin Zhang🇺🇸 · Jason Detwiler🇺🇸 · Clint Wiseman🇺🇸

    We study neutrino, muon, and gamma-ray fluxes in extraterrestrial environments in our Solar System via semi-analytical estimates and Monte Carlo simulations. In sites with negligible atmosphere, we find a strong reduction in the cosmic-ray-induced neutrino and muon fluxes relative to their intensities on Earth. Neutrinos with energies between 50 MeV and 100 TeV show particularly strong suppression, by as much as 10${}^3$, even at shallow depths. The solar neutrino suppression increases as the square of the site's distance from the Sun. Natural radiation due to nuclear decay is also expected to be lower in many of these locations and may be reduced to effectively negligible levels in the liquid water environments. The sites satisfying these characteristics represent an opportunity for greatly extending the physics reach of underground searches in fundamental physics, such as searches for WIMP Dark Matter, neutrinoless double-beta decay, the diffuse supernova neutrinos, and neutrinos from nearby supernova. As a potential near-term target, we propose a measurement of muon and gamma-ray fluxes in an accessible underground lunar site such as the Mare Tranquillitatis Pit to perform a first measurement of the prompt component in cosmic-ray-induced particle production, and to constrain lunar evolution models.

    ↳ hep-exastro-ph.EPhep-phnucl-ex+10 citations
27. 27*

    Hadronic vacuum polarization for the muon $g-2$ from lattice QCD: Complete short and intermediate windows

    Alexei Bazavov🇺🇸 · David A. Clarke🇺🇸 · Christine Davies🇬🇧 · Carleton DeTar🇺🇸 · Aida X. El-Khadra🇺🇸 · Elvira Gámiz🇪🇸 · Steven Gottlieb🇺🇸 · Anthony V. Grebe🇺🇸 · Leon Hostetler🇺🇸 · William I. Jay🇺🇸 · Hwancheol Jeong🇺🇸 · Andreas S. Kronfeld🇺🇸 and 12 other authors

    We present complete results for the hadronic vacuum polarization (HVP) contribution to the muon anomalous magnetic moment $a_{\mu }$ in the short- and intermediate-distance window regions, which account for roughly 10% and 35% of the total HVP contribution to $a_{\mu }$, respectively. In particular, we perform lattice-QCD calculations for the isospin-symmetric connected and disconnected contributions, as well as corrections due to strong isospin-breaking. For the short-distance window observables, we investigate the so-called log-enhancement effects as well as the significant oscillations associated with staggered quarks in this region. For the dominant, isospin-symmetric light-quark connected contribution, we obtain $a_{\mu }^{ll,\mathrm{SD}}(conn.)=48.139(11{)}_{\mathrm{stat}}(91{)}_{\mathrm{syst}}[92{]}_{\mathrm{total}}\times 10^{-10}$ and $a_{\mu }^{ll,\mathrm{W}}(conn.)=206.90(14{)}_{\mathrm{stat}}(61{)}_{\mathrm{syst}}[63{]}_{\mathrm{total}}\times 10^{-10}$. We use Bayesian model averaging to fully estimate the covariance matrix between the individual contributions. Our determinations of the complete window contributions are $a_{\mu }^{\mathrm{SD}}=69.05(1{)}_{\mathrm{stat}}(21{)}_{\mathrm{syst}}[21{]}_{\mathrm{total}}\times 10^{-10}$ and $a_{\mu }^{\mathrm{W}}=236.45(17{)}_{\mathrm{stat}}(83{)}_{\mathrm{syst}}[85{]}_{\mathrm{total}}\times 10^{-10}$. This work is part of our ongoing effort to compute all contributions to HVP with an overall uncertainty at the few permille level.

    ↳ hep-lathep-exhep-phPRD(2025)·66 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.