Mon·Nov 4, 2024Monday·November 4, 2024

1. 01*

   The quark gap equation in light-cone gauge

   Roberto Correa da Silveira🇧🇷 · Fernando E. Serna🇨🇴 · Bruno El-Bennich🇧🇷

   We calculate the quark self-energy correction in light-cone gauge motivated by distribution amplitudes whose definition implies a Wilson line. The latter serves to preserve the gauge invariance of the hadronic amplitudes and becomes trivial in light-cone gauge. Therefore, the calculation of the distribution amplitudes simplifies significantly provided that wave functions and propagators are obtained in that gauge. In here, we explore the corresponding Dyson-Schwinger equation in its leading truncation and with a dressed vertex derived from a Ward identity in light-cone gauge. The quark's mass and wave renormalization functions, as well as a third complex-valued amplitude, are found to depend on the relative orientation of the quark momentum and a light-like four-vector, which expresses a geometric gauge dependence of the propagator.

   hep-phnucl-thPRD(2025)·0 citations
2. 02*

   Is Ball Lightning a Signal of Magnetic Monopoles?

   John P. Ralston🇺🇸

   While ball lighting is known to exist from thousands of observations, its properties have never been explained by known physics. The combined order of magnitude of power, size, time scale, and characteristic behavior of ball lightning have defeated every model. The failure of standard physics does not hinge on fine details, but on the breadth of qualitative features of the phenomenon itself. We consider the possibility that ball lighting may be a signal of physics beyond the Standard Model. The mass and energy scale of ball lightning is remarkably consistent with new physics scales of grand unified theories. We analyze a suggestion that monopole catalysis of baryon decays in air might explain ball lightning. Nothing can be done to make it consistent, including saturating interaction cross sections with unitarity bounds. However a high mass dyon partially decaying by neutralization of deeply bound electromagnetic energy explains several puzzles naturally. The study suggests new ways to search for dyons and monopoles. The organizational skills of ambitious experimental physics groups could lead to productive searches beyond the Standard Model that do not need a new particle accelerator.

   hep-ph2 citations
3. 03*

   Estimate of the $S$-wave $D^{\ast }K$ scattering length in the isospin-0 channel from Belle and LHCb data

   N. N. Achasov🇷🇺 · G. N. Shestakov🇷🇺

   It is shown that the Belle and LHCb data on the interference of the amplitudes of the $S$ and $D$ partial waves in the decays $D_{s1}(2536{)}^{+}\to D^{\ast +}{K}_S^0$ and $D_{s1}(2536{)}^{-}\to {\bar{D}}^{\ast 0}{K}^{-}$ allow us to obtain an estimate of the $S$-wave $D^{\ast }K$ scattering length in the channel with isospin $I=0$: $|a_{D^{\ast }K}^{(0)}|=(0.94\pm 0.06)$ fm. The possibility of explaining the found value by the contribution of the $D_{s1}(2460)$ resonance is discussed. The decay of $B_{s1}(5830)\to B^{\ast }\bar{K}$ is also briefly discussed.

   hep-phhep-exnucl-exnucl-thPRD(2025)·0 citations
4. 04*

   A Lorentz-Equivariant Transformer for All of the LHC

   Johann Brehmer🇳🇱 · Víctor Bresó🇩🇪 · Pim de Haan🇳🇱 · Tilman Plehn🇩🇪 · Huilin Qu🇨🇭 · Jonas Spinner🇩🇪 · Jesse Thaler🇺🇸

   We show that the Lorentz-Equivariant Geometric Algebra Transformer (L-GATr) yields state-of-the-art performance for a wide range of machine learning tasks at the Large Hadron Collider. L-GATr represents data in a geometric algebra over space-time and is equivariant under Lorentz transformations. The underlying architecture is a versatile and scalable transformer, which is able to break symmetries if needed. We demonstrate the power of L-GATr for amplitude regression and jet classification, and then benchmark it as the first Lorentz-equivariant generative network. For all three LHC tasks, we find significant improvements over previous architectures.

   hep-phcs.LGhep-exSciPost Phys.(2025)·88 citations
5. 05*

   CP violation of the loop induced $H^{\pm }\to W^{\pm }Z$ decays in general two Higgs doublet model

   Shinya Kanemura🇯🇵 · Yushi Mura🇯🇵

   New sources of CP violation are necessary to solve the problem of the baryon asymmetry of the Universe. Extending Higgs sector is one way to introduce such new CP violating phases, and studying observables resulting from the CP violation is important to test the model in future experiments. In these proceedings, we discuss the loop induced $H^{\pm }{W}^{\mp }Z$ vertices in the CP violating general two Higgs doublet model, summarizing our results. We evaluate impacts of the CP violation on the decays $H^{\pm }\to W^{\pm }Z$ through these vertices, and find that the difference between the decays $H^{+}\to W^{+}Z$ and $H^{-}\to W^{-}Z$ is sensitive to the CP violating phases in the model.

   hep-phEPJ Web Conf.(2024)·0 citations
6. 06*

   Lepton Flavor Violation in Nonholomorphic Soft SUSY-Breaking Scenarios: Experimental Limits and Excesses

   Muhammad Rehman🇵🇰 · Sven Heinemeyer🇪🇸

   We investigate the prospects for the observation of lepton flavor violation (LFV) within the nonholomorphic supersymmetric standard model (NHSSM). We examine charged lepton flavor-violating (cLFV) decays such as such $\mu \to e\gamma$, $\tau \to e\gamma$ and $\tau \to \mu \gamma$ to impose indirect constraints on both LFV holomorphic and nonholomorphic (NH) soft Supersymmetry-breaking (SSB) terms. These constraints are subsequently utilized to calculate decay rates for LFV Higgs decays (LFVHD). Within the allowed parameter space, NH contributions to LFVHD can be notably larger compared to the holomorphic counterparts. Interestingly, recently ATLAS reported an excess larger than $2\sigma$ in their searches for $h\to e\tau$ and $h\to \mu \tau$. Their best-fit point is not excluded by the corresponding CMS limits. We demonstrate that for some parts of parameter space, the predicted values for $\text{BR}(h\to e\tau )$ and $\text{BR}(h\to \mu \tau )$ in the NH scenarios reach up to the present experimental limit for these decay processes and can potentially explain the excesses observed by ATLAS, while being in agreement with other experimental constraints. If these decays are eventually observed experimentally, they could potentially serve as a distinctive signature of the NH scenarios and determine some of the NH parameters. Conversely, the limits on the LFVHDs can restrict the allowed parameter space for the NH SSB terms in the NHSSM.

   hep-phEPJC(2025)·7 citations
7. 07*

   The Quest for Understanding: The Case of the Upgraded Superconducting Super Collider

   Alon E. Faraggi🇬🇧

   Fundamental particle physics is at a cross road. On the one hand the Standard Model successfully accounts for all experimental observations to date. On the other hand the ElectroWeak symmetry breaking mechanism is poorly understood and suggests the existence of new physics within reach of future colliders. Building on LHC experience, a hadron collider using the well established LHC magnet technology in a 90--100km circular ring, can reach the required 50--60TeV energy range and uncover the next layers of reality by the early 2040s.

   hep-phhep-exhep-thPHEP(2025)·2 citations
8. 08*

   A Practical Guide to Statistical Techniques in Particle Physics

   Alejandro Segura🇨🇴 · Angie Catalina Parra🇨🇴

   In high-energy physics (HEP), both the exclusion and discovery of new theories depend not only on the acquisition of high-quality experimental data but also on the rigorous application of statistical methods. These methods provide probabilistic criteria (such as p-values) to compare experimental data with theoretical models, aiming to describe the data as accurately as possible. Hypothesis testing plays a central role in this process, as it enables comparisons between established theories and potential new explanations for the observed data. This report reviews key statistical methods currently employed in particle physics, using synthetic data and numerical comparisons to illustrate the concepts in a clear and accessible way. Our results highlight the practical significance of these statistical tools in enhancing the experimental sensitivity and model exclusion capabilities in HEP. All numerical results are estimated using Python and RooFit, a high-level statistical modeling package used by the ATLAS and CMS collaborations at CERN to model and report results from experimental data.

   hep-ph4 citations
9. 09*

   Gauge coupling jump and small instantons from a large non-minimal coupling

   Juntaro Wada🇯🇵 · Wen Yin🇯🇵

   If a scalar field couples to the Ricci scalar with a large non-minimal coupling, the Standard Model coupling parameters can differ above and below an intermediate field range of the scalar due to the non-renormalizability. In this paper, we study, for the first time, the threshold effects on a gauge coupling in both Metric and Palatini formulations of gravity. We find that the gauge coupling naturally jumps around this intermediate scale since counter terms for the renormalization behave so. If the gauge coupling becomes strong with a large scalar field value due to this effect, there can be an enhanced small instanton contribution, the dilute gas approximation of which is justified because the gauge sector decouples when the scalar wave mode is very short. Using these findings, we discuss the QCD axion quality problem, the heavy QCD axion, the QCD axion abundance, and the suppression of isocurvature perturbations. We show that axion physics may differ substantially from naïve expectations when we introduce a large non-minimal coupling for any scalar field.

   hep-phastro-ph.COhep-thPTEP(2025)·2 citations
10. 10*

    New physics decaying into metastable particles: impact on cosmic neutrinos

    Kensuke Akita🇯🇵 · Gideon Baur🇩🇪 · Maksym Ovchynnikov🇨🇭 · Thomas Schwetz🇩🇪 · Vsevolod Syvolap🇳🇱

    We investigate decays of hypothetical unstable new physics particles into metastable species such as muons, pions, or kaons in the Early Universe, when temperatures are in the MeV range, and study how they affect cosmic neutrinos. We demonstrate that the non-trivial dynamics of metastables in the plasma alters the impact of the new physics particles on the neutrino population, including the effective number of neutrino degrees of freedom, $N_{\mathrm{eff}}$, modifies neutrino spectral distortions, and may induce asymmetries in neutrino and antineutrino energy distributions. These modifications have important implications for observables such as Big Bang Nucleosynthesis and the Cosmic Microwave Background, especially in light of upcoming CMB observations aiming to reach percent-level precision on $N_{\mathrm{eff}}$. We illustrate our findings with a few examples of new physics particles and provide a computational tool available for further exploration.

    hep-phastro-ph.COPRL(2025)·18 citations
11. 11*

    Zero-bias new particle searches using autoencoders in UPCs and diffractive events

    Simone Ragoni🇺🇸 · Janet Seger🇺🇸 · Christopher Anson🇺🇸

    We present an application of unsupervised learning for zero-bias detection of rare particle decays and exotic hadrons in low-background environments such as those characteristic of diffractive events and ultraperipheral pp, p--A, or A--A collisions at the CERN Large Hadron Collider (LHC), or in e--A collisions at the ePIC experiment at the future Electron-Ion Collider (EIC). Using a toy dataset simulating the decays of known resonances, including $\text{ensuremath}\mathrm{J}/\psi \text{xspace}$ and {\ensuremath{\psi'}\xspace}, as well as more exotic candidates, we implement an autoencoder neural network to identify anomalies in the decay kinematics. The autoencoder, trained solely on typical events, is designed to reconstruct normal decays with low error while flagging anomalous decays based on the reconstruction error. We demonstrate that the autoencoder successfully separates typical decays from rare exotic events, with peaks in the invariant mass distribution corresponding to the injected rare signals. Our method shows promise in detecting rare, unpredicted processes in large-scale collider data, offering an effective approach for discovering new physics beyond the Standard Model.

    hep-phhep-ex3 citations
12. 12*

    Exploring New Physics in transition $b\to s{\ell }^{+}{\ell }^{-}$ through different $B_c\to D_s^{(\ast )}{\ell }^{+}{\ell }^{-}$ observables

    Qazi Maaz Us Salam🇵🇰 · Ishtiaq Ahmed🇵🇰 · Rizwan Khalid🇵🇰 · Ibad Ur Rehman🇵🇰

    Inspired by the discrepancies observed in the $b\to s{\ell }^{+}{\ell }^{-}$ neutral current decays, we study the decay channel $B_c\to D_s^{(\ast )}{\ell }^{+}{\ell }^{-}$ ($\ell =\mu ,\tau$), which is based on the same flavor changing neutral current (FCNC) transition at the quark level. The current study shows that this decay channel can provide a useful probe for physics beyond the standard model. We use the helicity formalism while employing the effective theory approach where we include the effects of vector and axial vector `new' physics (NP) operators. In this study, we have computed the branching ratio ${\mathcal{B}}_r$, the $D^{\ast }$ helicity fraction $f_L$, the lepton forward-backward asymmetry ${\mathcal{A}}_{FB}$, and the lepton flavor universality ratio (LFU) $R_{D_s^{\ast }}^{\tau \mu }$. In addition, as a complementary check on the LFU, we also calculate the various other LFU observables, $R_i^{\tau \mu }$ where $i=A_{FB}$, $f_L$. We assume that the NP universal coupling is present for both muons and tauons, while the non-universal coupling is only present for muons. Regarding these couplings, we employ the latest global fit to the $b\to s{\ell }^{+}{\ell }^{-}$ data, which is recently computed in arXiv:2304.07330. We give predictions of some of the mentioned observables within the SM and the various NP scenarios. We have found that not only are the considered observables sensitive to NP but are also helpful in distinguishing among the different NP scenarios. These results can be tested at the LHCb, HL-LHC, and FCC-ee, and therefore, a precise measurements of these observables not only deepens our understanding of the $b\to s{\ell }^{+}{\ell }^{-}$ process but also provides a window of opportunity to possibly study various NP scenarios.

    hep-phJ.Phys.G(2025)·8 citations
13. 13*

    Dynamics of metastable Standard Model particles from long-lived particle decays in the MeV primordial plasma

    Kensuke Akita🇯🇵 · Gideon Baur🇩🇪 · Maksym Ovchynnikov🇨🇭 · Thomas Schwetz🇩🇪 · Vsevolod Syvolap🇳🇱

    We investigate the cosmological impact of hypothetical unstable new physics particles that decay in the MeV-scale plasma of the Early Universe. Focusing on scenarios where the decays produce metastable species such as muons, pions, and kaons, we systematically analyze the dynamics of these particles using coupled Boltzmann equations governing their abundances. Our results demonstrate that the metastable species can efficiently annihilate or interact with nucleons, often leading to their disappearance before decay. The suppression of decay significantly alters the properties of cosmic neutrinos, impacting cosmological observables like Big Bang nucleosynthesis and the Cosmic Microwave Background. To support further studies, we provide two public codes: the Mathematica code that traces the evolution of these metastable particles, as well as the python-based unintegrated neutrino Boltzmann solver that uses this evolution as an input and may be applied to a broad range of scenarios. We then utilize them for studying a few particular new physics models.

    hep-phastro-ph.COPRD(2025)·14 citations
14. 14*

    Collider-Flavour Complementarity from the bottom to the top

    Oliver Atkinson🇬🇧 · Christoph Englert🇬🇧 · Matthew Kirk🇬🇧 · Gilberto Tetlalmatzi-Xolocotzi🇩🇪

    Motivated by recently observed anomalies in the flavour sector, we analyse the potential of measurements of top quarks at the Large Hadron Collider (LHC) to provide complementary constraints on interactions that shape low-energy precision investigations in the $B$ sector. The measurement of top quark properties, such as the top width and the abundant top pair production channels, are already reaching the percent level at this relatively early stage of the LHC phenomenology program. A focused analysis of four-fermion interactions, employing effective field theory without flavour structure assumptions and incorporating renormalization group evolution effects, bridges $B$ meson scale phenomena with key top quark measurements. We demonstrate that the LHC is increasingly competitive with, and complementary to, flavour physics constraints. Our results, which include a first comprehensive analysis of non-leptonic B decays in this context, suggest that the LHC's top physics program could serve as a valuable, complementary tool in the search for physics beyond the Standard Model within the flavour sector.

    hep-phhep-exEPJC(2025)·13 citations
15. 15*

    Profile Likelihoods on ML-Steroids

    Theo Heimel🇩🇪 · Tilman Plehn🇩🇪 · Nikita Schmal🇩🇪

    Profile likelihoods, for instance, describing global SMEFT analyses at the LHC are numerically expensive to construct and evaluate. Especially profiled likelihoods are notoriously unstable and noisy. We show how modern numerical tools, similar to neural importance sampling, lead to a huge numerical improvement and allow us to evaluate the complete SFitter SMEFT likelihood in five hours on a single GPU.

    hep-ph7 citations
16. 16*

    Pythia 8 and Air Shower Simulations: A Tuning Perspective

    Chloé Gaudu🇩🇪

    The Pierre Auger Observatory has revealed a significant challenge in air shower physics: a discrepancy between the simulated and observed muon content in cosmic-ray interactions, known as the 'Muon Puzzle'. This issue stems from a lack of understanding of high-energy hadronic interactions. Current state-of-the-art hadronic interaction models fall short, underscoring the need for improvements. In this contribution, we explore the integration of the Pythia 8 hadronic interaction model into air shower simulations. While Pythia 8 is primarily used in Large Hadron Collider experiments, recent advancements in its Angantyr module show promise in better describing hadron-nucleus interactions, making it a valuable tool for addressing the Muon Puzzle.

    ↳ astro-ph.HEhep-ph5 citations
17. 17*

    Attosecond physics hidden in Cherenkov radiation

    D. Karlovets🇷🇺 · A. Chaikovskaia🇷🇺 · D. Grosman🇷🇺 · D. Kargina🇷🇺 · A. Shchepkin🇷🇺 · G. Sizykh🇷🇺

    Cherenkov radiation of charged particles moving with superluminal velocities in transparent media is a well-studied phenomenon with a plethora of applications. Its microscopic origins can be traced to the polarization of atomic shells, characterized by time scales in the subfemtosecond range - dynamics that eludes conventional macroscopic treatment. Here we present a theoretical framework for probing the intrinsic dynamics of Cherenkov radiation, unveiling quantum features absent in classical realm and even in a fully quantum theory in momentum space. These features include a finite formation length and spreading time of the photon, the latter becoming negative nearby the Cherenkov angle, a finite flash duration tied to the size of the electron packet, along with a shift in the photon arrival time that can be either positive or negative and necessitates going beyond the far-field approximation. The calculated time scales lie in the attosecond range for the relevant parameters, thus linking this macroscopic phenomenon back to its atomic origins. Finally, we propose that by measuring the duration of the Cherenkov flash one can in principle retrieve the length of the emitting packet, deepening our understanding of quantum coherence effects in photon emission.

    ↳ quant-phhep-phphysics.acc-phphysics.atom-ph+1Commun.Phys.(2025)·3 citations
18. 18*

    Model-independent results on parity violation in the trace anomaly

    Rémy Larue🇫🇷 · Jérémie Quevillon🇫🇷 · Roman Zwicky🇬🇧

    Anomalous parity violation in four dimensions would be significant for phenomenology (baryogenesis, gravitational waves) and mathematical physics. Over the past decade, there has been a controversy in the literature as to whether free Weyl fermions give rise to (anomalous) parity violation in the trace of the energy momentum tensor; expressed by the Pontryagin densities $R\tilde{R}$ and $F\tilde{F}$ in the gravity and the gauge sector respectively. In Ref.${}^1$, we have shown, using path integral methods, that the trace anomaly of a free Weyl fermion does not violate parity (i.e the absence of the Pontryagin density). In a subsequent work${}^2$ we came to the stronger conclusion that for any theory compatible with dimensional regularisation, the Pontryagin-terms are equally absent. It is the \textit{finiteness} of the diffeomorphism, the Lorentz and the gauge anomalies that prevents anomalous parity violation.

    ↳ hep-thhep-ph3 citations
19. 19*

    Unlocking "imprints" of conserved charges in the initial state of heavy-ion collisions

    Fernando G. Gardim🇧🇷 · Dekrayat Almaalol🇺🇸 · Jordi Salinas San Martín🇺🇸 · Christopher Plumberg🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

    Hydrodynamic approaches to modeling relativistic high-energy heavy-ion collisions are based on the conservation of energy and momentum. However, the medium formed in these collisions also carries additional conserved quantities, including baryon number (B), strangeness (S), and electric charge (Q). In this Letter, we propose a new set of anisotropic flow observables designed to be exclusively sensitive to the effects of conserved BSQ charge fluctuations, providing insight into the initial state. Using the recently developed hydrodynamic framework \iccing{}+\ccake{}, we show that these new observables provide a measurable effect of initial BSQ charge fluctuations (ranging up to $\sim$10\%), which can be tested by experiments.

    ↳ nucl-thhep-phnucl-ex4 citations
20. 20*

    Primordial Black Holes and Second-order Gravitational Waves in Axion-like Hybrid Inflation

    Waqas Ahmed🇨🇳 · Anish Ghoshal🇵🇱 · Umer Zubair🇺🇸

    We investigate the possibility that primordial black holes (PBHs) can be formed from large curvature perturbations generated during the waterfall phase transition in a hybrid inflation model driven by an axion-like particle (ALP) $\varphi$. The model predicts a spectral index $n_s\simeq 0.964$ and a tensor-to-scalar ratio $r\simeq 0.003$, in agreement with Planck data and potentially testable by next generation cosmic microwave background (CMB) experiments such as CMB-S4 and LiteBIRD. We find that the PBH mass and the peak of the associated scalar-induced gravitational wave (SIGW) spectrum are correlated with the ALP mass. In particular, PBHs in the mass range $10^{-13}{M}_{\odot }$ can constitute either the entire dark matter (DM) content of the universe or a significant fraction of it. The predicted second-order GWs from this mechanism are within the sensitivity reach of future observatories like LISA and ET. The typical reheating temperature in the model is around $10^6-10^7$ GeV is consistent with Big Bang Nucleosynthesis (BBN) constraints.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2025)·6 citations
21. 21*

    Gravity and Unification: Insights from SL(2N,C) Gauge Theories

    J.L. Chkareuli🇬🇪

    The perspective that gravity may govern the unification of all elementary forces calls for extending the gauge-gravity symmetry $SL(2,C)$ to the broader local symmetry $SL(2N,C)$, where $N$ reflects the internal $SU(N)$ subgroup. This extension yields a consistent hyperunification framework in which -- aside from the linear gravity Lagrangian, to which only tensor fields contribute -- the quadratic curvature sector is fully unified across all gauge submultiplets. Tetrad fields play a central role: once dynamical, their invertibility -- treated as a nonlinear sigma-model type length constraint -- naturally implies condensation and thereby triggers spontaneous breaking of $SL(2N,C)$. As a result, while the full gauge multiplet contains vector, axial-vector, and tensor submultiplets, only the vector submultiplet remains in the observed spectrum; the axial-vector and tensor submultiplets acquire large masses at the symmetry-breaking scale. The effective symmetry reduces to $SL(2,C)\times SU(N)$, collecting together $SL(2,C)$ gauge gravity and the $SU(N)$ grand-unified sector. Since states in $SL(2N,C)$ are also classified by spin magnitudes, many $SU(N)$ GUT models -- such as standard $SU(5)$% -- appear ill-suited for fundamental spin-$1/2$ quarks and leptons. By contrast, applying $SL(2N,C)$ to a composite framework with chiral preons in fundamental representations points to $SL(16,C)$, with effective accommodating all three quark-lepton families, as a compelling candidate for hyperunification of all fundamental forces.

    ↳ hep-thhep-phNPB(2025)·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.