Mon·Aug 5, 2024Monday·August 5, 2024

1. 01*

   Large CP violation in flavor violating muon decays

   Diego Redigolo🇮🇹 · Michele Tammaro🇮🇹 · Andrea Tesi🇮🇹

   We identify new room for CP violation in lepton flavor violating observables not bound by the electric dipole moment of leptons. By focusing on new physics in the muon-electron sector, we show that CP violation can make its first appearance in lepton flavor violating muon decays rather than in the electric dipole moment of the electron, further motivating the experimental program of Mu3e. We tackle this issue by performing the full one-loop running and matching from the low energy observables at the muon scale, including the T-odd asymmetry in $\mu \to 3e$ decays, to the Standard Model effective field theory above the electroweak scale. We then sketch a simple UV model that can give rise to these patterns.

   hep-phEPJC(2025)·6 citations
2. 02*

   Impact of dark energy on the structure of neutron stars: The vacuum case

   L. F. Araujo🇧🇷 · J. A. S. Lima🇧🇷 · G. Lugones🇧🇷

   The potential role of a cosmic vacuum dark component in the properties of neutron stars is investigated. It is assumed that the static, spherically symmetric distribution of matter within neutron stars is supported by two distinct components: ordinary matter and a vacuum fluid. For normal matter we use a set of state-of-the-art nuclear matter equations of state, each grounded in nuclear physics experiments. The vacuum energy component is inhomogeneously distributed within the star and obeys the standard equation of state ($p_v=-{ϵ}_v$). This is characterized by an energy density fraction $y={ϵ}_m/({ϵ}_m+{ϵ}_v)$, which we model as either a constant or radius-dependent. Our findings reveal that the inclusion of vacuum energy significantly affects the mass-radius relationships in neutron stars, influencing both the maximum achievable masses and the qualitative form of these relationships. Some constraints from current multimessenger observational data limiting the amount of vacuum energy within neutron stars are also discussed.

   hep-phastro-ph.HEastro-ph.SRgr-qc+1PRD(2024)·6 citations
3. 03*

   Higgs boson production at ${\mu }^{+}{\mu }^{+}$ colliders

   Yu Hamada🇩🇪 · Ryuichiro Kitano🇯🇵 · Ryutaro Matsudo🇯🇵 · Shohei Okawa🇯🇵 · Ryoto Takai🇯🇵 · Hiromasa Takaura🇯🇵 · Lukas Treuer🇯🇵

   We study Higgs boson production at ${\mu }^{+}{\mu }^{+}$ colliders at high energy. Since both initial-state particles are positively charged, there is no $W$ boson fusion at the leading order, as it requires a $W^{+}{W}^{-}$ pair. However, we find that the cross section of the higher-order, $\gamma$- and $Z$-mediated $W$ boson fusion process is large at high center-of-mass energies $\sqrt{s}$, growing as $(\log s{)}^3$. This is in contrast to the $\log s$ behavior of the leading-order $W$ boson fusion. Thus, even though it is a higher-order process, the rate of Higgs boson production for 10 TeV energies at ${\mu }^{+}{\mu }^{+}$ colliders with polarized beams can be as high as about half of the one at ${\mu }^{+}{\mu }^{-}$ colliders, assuming the same integrated luminosity. To calculate the cross section of this process accurately, we carefully treat the collinear emission of the photon in the intermediate state. The thereby obtained large cross section furthermore shows the significance of Higgs production with an extra $W$ boson in the final state also at ${\mu }^{+}{\mu }^{-}$ and $e^{+}{e}^{-}$ colliders.

   hep-phPRD(2024)·7 citations
4. 04*

   Model Independent Tests of the Hadronic Vacuum Polarization Contribution to the Muon $g$$-$$2$

   Luca Di Luzio🇮🇹 · Alexander Keshavarzi🇬🇧 · Antonio Masiero🇮🇹 · Paride Paradisi🇮🇹

   The hadronic vacuum polarization (HVP) contributions to the muon $g$$-$$2$ are the crucial quantity to resolve whether new physics is present or not in the comparison between the Standard Model (SM) prediction and experimental measurements at Fermilab. They are commonly and historically determined via dispersion relations using a vast catalogue of experimentally measured, low-energy $e^{+}{e}^{-}\to \mathrm{hadrons}$ cross section data as input. These dispersive estimates result in a SM prediction that exhibits a muon $g$$-$$2$ discrepancy of more than $5\sigma$ when compared to experiment. However, recent lattice QCD evaluations of the HVP and a new hadronic cross section measurement from the CMD-3 experiment favor a no-new-physics scenario and, therefore, exhibit a common tension with the previous $e^{+}{e}^{-}\to \mathrm{hadrons}$ data. This study explores the current and future implications of these two scenarios on other observables that are also sensitive to the HVP contributions in the hope that they may provide independent tests of the current tensions observed in the muon $g$$-$$2$.

   hep-phhep-exhep-latPRL(2025)·44 citations
5. 05*

   A method to include exclusive heavy vector-meson production data at small $x$ in global parton analyses

   C. A. Flett🇫🇷 · A. D. Martin🇬🇧 · M. G. Ryskin🇷🇺 · T. Teubner🇬🇧

   We propose a method which allows the inclusion of exclusive heavy vector-meson production data at low $x$ in future global parton analyses. As an example we perform a study within xFitter to determine the gluon parton distribution function (PDF) at next-to-leading order (NLO) at moderate-to-low $x$ using the measurements of exclusive $J/\psi$ production in ep and pp collisions from HERA and LHC. We further study the constraints from the corresponding ${\rm Y}$ production process. We finish by discussing the possible effects at next-to-next-to-leading order (NNLO) through incorporation of a K factor for the exclusive heavy vector-meson coefficient function at NLO.

   hep-phEPJC(2025)·7 citations
6. 06*

   Interplay of Traditional Methods and Machine Learning Algorithms for Tagging Boosted Objects

   Camellia Bose🇮🇳 · Amit Chakraborty🇮🇳 · Shreecheta Chowdhury🇮🇳 · Saunak Dutta🇮🇳

   Interest in deep learning in collider physics has been growing in recent years, specifically in applying these methods in jet classification, anomaly detection, particle identification etc. Among those, jet classification using neural networks is one of the well-established areas. In this review, we discuss different tagging frameworks available to tag boosted objects, especially boosted Higgs boson and top quark, at the Large Hadron Collider (LHC). Our aim is to study the interplay of traditional jet substructure based methods with the state-of-the-art machine learning ones. In this methodology, we would gain some interpretability of those machine learning methods, and which in turn helps to propose hybrid taggers relevant for tagging of those boosted objects belonging to both Standard Model (SM) and physics beyond the SM.

   hep-phhep-exEur.Phys.J.ST(2024)·5 citations
7. 07*

   Type-II seesaw of a non-holomorphic modular $A_4$ symmetry

   Takaaki Nomura🇨🇳 · Hiroshi Okada🇨🇳

   We search for predictability of lepton masses and mixing patterns of type-II seesaw scenario in a non-holomorphic modular $A_4$ symmetry recently proposed by Qu and Ding. We propose three types of minimum predictive models with different assignments of modular weight, satisfying the neutrino oscillation data in Nufit 5.2. The cosmological bound on the sum of neutrino mass is stringent to our models and CMB bound $\sum D_{\nu }\le 0.12$ eV can be satisfied by one of three models playing an important role in discriminating them.

   hep-phPLB(2025)·32 citations
8. 08*

   Impact of new particles on the ratio of Electromagnetic form factors

   A. Rafiei🇮🇷 · M. Haghighat🇮🇷

   We consider the electromagnetic form factors ratio in the Rosenbluth and polarization methods. We explore the impact of adding new particles as the mediators in the electron-proton scattering on these ratios. Consequently, we find some bound on the scalar coupling as ${\alpha }_{sc}\sim 10^{-5}$ for $m_{sc}\sim 5MeV-2GeV$ and ${\alpha }_{sc}\sim 10^{-4}-10^{-3}$ for $m_{sc}\sim 2-10GeV$. Meanwhile, the vector coupling is bounded as ${\alpha }_v\sim 10^{-5}$ for $m_v\sim 5MeV-1.1GeV$ and ${\alpha }_v\sim 10^{-4}-10^{-3}$ for $m_v\sim 1.2-10GeV$. These constraints are in complete agreement with those which is found from other independent experiments.

   hep-phhep-thJ.Phys.G(2025)·2 citations
9. 09*

   Spontaneous magnetization of QGP at high temperature

   Volodymyr Skalozub🇺🇦

   In quark-gluon plasma (QGP), at higher deconfinement temperatures $T\ge T_d$ the spontaneous generation of color magnetic fields, $b^3(T),b^8(T)\ne 0$ (3, 8 are color indexes), and usual magnetic field $b(T)\ne 0$ happens. Simultaneously, the Polyakov loop and/or algebraically related to it $A_0(T)$ condensate, which is solution to Yang-Mills imaginary time equations, are also created. Usually, in analytic quantum field theory these effects are investigated independently of each other within the effective potentials having different mathematical structures. The common generation of these condensates was detected in lattice Monte Carlo simulations. Recently, with the new type two-loop effective potential, which generalizes the known integral representation for the Bernoulli polynomials and takes into consideration the magnetic background, this effect has been derived analytically. The corresponding effective potential W(T, b^3, A_0 ) was investigated either in SU(2) gluodynamics or full QCD. The gauge fixing independence of it was proved within the Nielsen identity approach. The values of magnetic field strengths at different temperatures were calculated and the mechanism of stabilizing fields due to A_0(T) condensate has been discovered. In the present review, we describe this important phenomenon in more details, as well as a number of specific effects - induced color charges, effective photon-photon-gluon vertexes - happening due to vacuum polarization at this background. They could serve as the signals of the QGP creation in the heavy ion collision experiments. Key words: spontaneous magnetization, high temperature, asymptotic freedom, effective potential, A_0 condensate, effective charge, effective vertexes.

   hep-ph0 citations
10. 10*

    Pole analysis for the $D^{\ast }\bar{K}$-$D\overline{K^{\ast }}$ coupled-channel system

    Pan-Pan Shi🇪🇸 · F. Gil-Domínguez🇪🇸 · R. Molina🇪🇸 · Meng-Lin Du🇨🇳

    By solving the Lippmann-Schwinger equation, possible hadronic molecules in the $D^{\ast }\bar{K}$-$D{\bar{K}}^{\ast }$ coupled-channel system are investigated with the one-meson exchange potentials, where both vector and pseudoscalar mesons are considered as exchange particles. We find an S-wave virtual state with mass $M=2487$ MeV, and a resonance with $M=2759$ and width $\Gamma =18$ MeV. In the $D^{\ast }\bar{K}$ invariant mass distribution, the virtual state appears as a cusp at the $D^{\ast }\bar{K}$ threshold, while the resonance potentially manifests as a dip. In particular, we take into account the $D\bar{K}\pi$ three-body dynamics due to the on-shell pion exchange and the finite decay width for ${\bar{K}}^{\ast }$.

    hep-phhep-exnucl-thPLB(2025)·5 citations
11. 11*

    Transverse momentum dependence of the $T$-even hadronic structure functions in the Drell-Yan process

    Valery E. Lyubovitskij🇩🇪 · Alexey S. Zhevlakov🇷🇺 · Iurii A. Anikin🇷🇺

    We present detailed analysis of the $T$-even lepton angular distribution in the Drell-Yan process including $\gamma /Z^0$ gauge boson exchange and using perturbative QCD based on the collinear factorization scheme at leading order in the ${\alpha }_s$ expansion. We focus on the study of the transverse momentum $Q_T$ dependence of the corresponding hadronic structure functions and angular coefficients up to next-next-to-leading order in the $Q_T^2/Q^2$ expansion. We analyze $Q_T$ dependence numerically and compare $T$-even angular coefficients integrated over rapidity with available data of the ATLAS Collaboration at LHC. Additionally, we present our results for the forward-backward asymmetry and compare it with data.

    hep-phPRD(2024)·4 citations
12. 12*

    QCD evolution of entanglement entropy

    Martin Hentschinski🇲🇽 · Dmitri E. Kharzeev🇺🇸 · Krzysztof Kutak🇵🇱 · Zhoudunming Tu🇺🇸

    Entanglement entropy has emerged as a novel tool for probing nonperturbative quantum chromodynamics (QCD) phenomena, such as color confinement in protons. While recent studies have demonstrated its significant capability in describing hadron production in deep inelastic scatterings, the QCD evolution of entanglement entropy remains unexplored. In this work, we investigate the differential rapidity-dependent entanglement entropy within the proton and its connection to final-state hadrons, aiming to elucidate its QCD evolution. Our analysis reveals a strong agreement between the rapidity dependence of von Neumann entropy, obtained from QCD evolution equations, and the corresponding experimental data on hadron entropy. These findings provide compelling evidence for the emergence of a maximally entangled state, offering new insights into the nonperturbative structure of protons.

    hep-phhep-exhep-thquant-phRept.Prog.Phys.(2024)·54 citations
13. 13*

    Towards UV Models of Kinetic Mixing and Portal Matter: A More Complex Dark Matter Sector?

    Thomas G. Rizzo🇺🇸

    Portal Matter, with both SM and dark charges, induces KM between the $U(1{)}_D$ dark photon and the SM gauge fields offering an attractive mechanism by which light thermal DM can obtain its observed relic density. If DM is fermionic, the CMB informs us that it must be Majorana/pseudo-Dirac in nature to avoid temperature-independent $s$-wave annihilation to SM states. How does this fit into a more complete picture with the SM? A first step along this path may not lie far away in energy due to the RGE running of the dark gauge coupling which can becomes non-perturbative before the $\sim 10$'s of TeV range. This implies that $U(1{)}_D$ must become embedded in a non-Abelian group, $G_D$, before this occurs. The breaking of this group then produces the PM masses and the heavy gauge fields associated with $G_D$ lead to new interactions between the SM and the dark sector. In the past we have examined a set of distinctive phenomenological features associated with this setup, based upon a number of simplifying assumptions. It behooves us to explore the impact of these assumptions on the predictions for possible experimental tests of these models. In past analyses we assumed that DM is a VL, complex singlet under $G_D$. If this assumption is relaxed, the dark sector must be augmented by additional fermion(s) and the scalar fields needed to break the symmetries while generating the needed Majorana-like mass terms for the DM. Here we analyze the simplest extension of this kind wherein the DM lies in a VL doublet of $G_D$, which we take to have the structure $SU(2{)}_I\times U(1{)}_{Y_I}$, leading to new phenomenology. We find that given the current LHC search constraints on the masses of heavy gauge bosons, the production of these new dark states with large rates is unlikely at colliders unless they are produced singly in $gg$-fusion or are resonantly enhanced.

    hep-phPRD(2024)·13 citations
14. 14*

    Discovering heavy neutrino-antineutrino oscillations at the $Z$-pole

    Stefan Antusch (U. Basel)🇨🇭 · Jan Hajer (CFTP, IST, U. Lisboa)🇵🇹 · Bruno M. S. Oliveira (CFTP, IST, U. Lisboa)🇵🇹

    Collider-testable type I seesaw extensions of the Standard Model are generally protected by an approximate lepton number (LN) symmetry. Consequently, they predict pseudo-Dirac heavy neutral leptons (HNLs) composed of two nearly degenerate Majorana fields. The interference between the two mass eigenstates can induce heavy neutrino-antineutrino oscillations (NNOs) leading to observable lepton number violation (LNV), even though the LN symmetry is approximately conserved. These NNOs could be resolved in long-lived HNL searches at collider experiments, such as the proposed Future Circular $e^{+}{e}^{-}$ Collider (FCC-$ee$) or Circular Electron Positron Collider (CEPC). However, during their $Z$-pole runs, the LN carried away by the light (anti)neutrinos produced alongside the HNLs prevents LNV from being observed directly. Nevertheless, NNOs materialise as oscillating signatures in final state distributions. We discuss and compare a selection of such oscillating observables, and perform a Monte Carlo simulation to assess the parameter space in which NNOs could be resolved.

    hep-phhep-exJHEP(2024)·12 citations
15. 15*

    Magnets are Weber Bar Gravitational Wave Detectors

    Valerie Domcke🇨🇭 · Sebastian A. R. Ellis🇨🇭 · Nicholas L. Rodd🇺🇸

    When a gravitational wave (GW) passes through a DC magnetic field, it couples to the conducting wires carrying the currents which generate the magnetic field, causing them to oscillate at the GW frequency. The oscillating currents then generate an AC component through which the GW can be detected - thus forming a resonant mass detector or a Magnetic Weber Bar. We quantify this claim and demonstrate that magnets can have exceptional sensitivity to GWs over a frequency range demarcated by the mechanical and electromagnetic resonant frequencies of the system; indeed, we outline why a magnetic readout strategy can be considered an optimal Weber bar design. The concept is applicable to a broad class of magnets, but can be particularly well exploited by the powerful magnets being deployed in search of axion dark matter, for example by DMRadio and ADMX-EFR. Explicitly, we demonstrate that the MRI magnet that is being deployed for ADMX-EFR can achieve a broadband GW strain sensitivity of $\sim$$10^{-20}/\sqrt{\text{Hz}}$ from a few kHz to about 10 MHz, with a peak sensitivity down to $\sim$$10^{-22}/\sqrt{\text{Hz}}$ at a kHz exploiting a mechanical resonance.

    hep-phastro-ph.IMgr-qchep-exPRL(2025)·42 citations
16. 16*

    Old neutron stars as a new probe of relic neutrinos and sterile neutrino dark matter

    Saurav Das🇺🇸 · P. S. Bhupal Dev🇺🇸 · Takuya Okawa🇺🇸 · Amarjit Soni🇺🇸

    We study the kinetic cooling (heating) of old neutron stars due to coherent scattering with relic neutrinos (sterile neutrino dark matter) via Standard Model neutral-current interactions. We take into account several important physical effects, such as gravitational clustering, coherent enhancement, neutron degeneracy and Pauli blocking. We find that the anomalous cooling of nearby neutron stars due to relic neutrino scattering might actually be observable by current and future telescopes operating in the optical to near-infrared frequency band, such as the James Webb Space Telescope (JWST), provided there is a large local relic overdensity that is still allowed. Similarly, the anomalous heating of neutron stars due to coherent scattering with keV-scale sterile neutrino dark matter, could also be observed by JWST or future telescopes, which would probe hitherto unexplored parameter space in the sterile neutrino mass-mixing plane.

    hep-phastro-ph.HEastro-ph.SRnucl-thPRD(2025)·15 citations
17. 17*

    Differentiable MadNIS-Lite

    Theo Heimel🇩🇪 · Olivier Mattelaer🇧🇪 · Tilman Plehn🇩🇪 · Ramon Winterhalder🇧🇪

    Differentiable programming opens exciting new avenues in particle physics, also affecting future event generators. These new techniques boost the performance of current and planned MadGraph implementations. Combining phase-space mappings with a set of very small learnable flow elements, MadNIS-Lite, can improve the sampling efficiency while being physically interpretable. This defines a third sampling strategy, complementing VEGAS and the full MadNIS.

    hep-phhep-exphysics.comp-phSciPost Phys.(2025)·50 citations
18. 18*

    Restricting Sterile Neutrinos by Neutrinoless Double Beta Decay

    Sudip Jana🇩🇪 · Lucas Puetter🇩🇪 · Alexei Yu. Smirnov🇩🇪

    The bounds on parameters of the eV and higher scale sterile neutrinos from the $0\nu \beta \beta$ decay have been refined and updated. We present a simple and compact analytic expression for the bound in the $\Delta m_{41}^2-{\sin }^{2}2{\theta }_{14}$ plane, which includes all relevant parameters. Dependencies of the bound on unknown CP-phases and the type of mass spectrum of light neutrinos (mass ordering and level of degeneracy) are studied in detail. We have computed the bounds using the latest and most stringent data from KamLAND-Zen. The projected constraints from future experiments are estimated. The obtained bounds are confronted with positive indications of the presence of sterile neutrinos as well as with the other existing bounds. The $0\nu \beta \beta$ decay results exclude the regions of parameters implied by BEST and Neutrino-4, and the regions indicated by LSND and MiniBooNE are in conflict with $0\nu \beta \beta$ results combined with ${\nu }_{\mu }-$ disappearance bounds.

    hep-phhep-exnucl-exnucl-thPRD(2025)·8 citations
19. 19*

    Neutron Stars as a Probe of Cosmic Neutrino Background

    Garv Chauhan🇺🇸

    The Cosmic Neutrino Background (C$\nu$B) constitutes the last observable prediction of the standard cosmological model, which has yet to be detected directly. In this work, we show how the coherent scattering of neutrinos off dense neutron matter can lead to an additional cooling channel in neutron stars (NSs). We also include the effects of gravitational capture and boosting, but find that the cooling is efficient only in the presence of large overdensities. We further discuss the prediction of a boosted C$\nu$B flux on Earth from nearby NSs and the potential detection prospects in the case of a future nearby galactic supernova. Although currently these ideas do not offer any detection prospects, they can be used to constrain overdensities $\eta \lesssim 10^{11}\text{-}10^{14}$ on short length scales $\mathcal{O}(10\text{ km})$. We also discuss the impact of new physics scenarios, such as long-range forces, on NS cooling through the C$\nu$B.

    hep-phastro-ph.HEPRD(2025)·10 citations
20. 20*

    Phenomenology of an Extended $1+2$ Higgs Doublet Model with $S_3$ Family Symmetry

    A. E. Cárcamo Hernández🇨🇱 · Daniel Salinas-Arizmendi🇨🇱 · Jonatan Vignatti🇦🇲 · Alfonso Zerwekh🇨🇱

    In order to explain the mass hierarchy and mixing pattern in the leptonic sector, we explore an extension of the Standard Model whose scalar sector includes one active and two inert doublets as well as some scalar singlets. The model includes a $S_3$ family symmetry supplemented by extra cyclic symmetries. As a consequence of our construction, a Dark Matter (DM) candidate is predicted and its properties are consistent with the observed cosmic abundances and the constraints imposed by direct and indirect detection experiments. The model allows Charged Lepton Flavor Violation (CLFV) processes like $\mu \to e\gamma$ and $\mu \to 3e$, but the predicted branching ratios align with experimental limits. Additionally, our analysis elucidates the generation of the active neutrino masses through a one-loop radiative seesaw mechanism matching the observed neutrino oscillation data. The model agrees with experimental data on Higgs Diphoton decay rates and on oblique parameters.

    hep-phEPJC(2024)·9 citations
21. 21*

    Thermodynamics of the parity-doublet model: Asymmetric and neutron matter

    Jürgen Eser🇩🇪 · Jean-Paul Blaizot🇫🇷

    We consider isospin-asymmetric matter in the parity-doublet model within an extended mean-field calculation, increasing continuously the neutron excess all the way to pure neutron matter. We compute the liquid-gas and the chiral phase transitions occurring at zero to moderate temperatures, but put special emphasis on the phase structure of matter at zero temperature and large baryon densities. The calculation of the free energy involves the solution of gap equations. This is achieved by transforming these gap equations into ordinary differential equations that control the flow with increasing baryon density of various physical quantities: the isoscalar condensate, the densities of protons and neutrons, as well as those of their respective chiral partners. In this formulation, the initial conditions for the differential equations determine the entire phase structure. It is further demonstrated that the threshold for the onset of the population of the chiral partners is exclusively determined by the fermionic parameters, most notably by the chiral-invariant mass of the nucleon. We underline the role of a parity symmetry energy in driving the equilibration of the nucleons and their parity partners across the chiral transition. We provide a detailed analysis of the changes in the matter properties as one varies the neutron excess, including a special discussion of the chiral limit, and we compare systematically the parity-doublet model to its corresponding singlet model, where the chiral partner of the nucleon is neglected. Finally, we focus on neutron matter and compute the equation of state and the speed of sound. The results are confronted to those of other calculations as well as to recent Bayesian analyses of neutron-star observations.

    ↳ nucl-thhep-phPRC(2024)·9 citations
22. 22*

    Cluster production and the chemical freeze-out in expanding hot dense matter

    D. Blaschke🇵🇱 · S. Liebing🇩🇪 · G. Röpke🇵🇱 · B. Dönigus🇩🇪

    We discuss medium effects on light cluster production in the QCD phase diagram by relating Mott transition lines to those for chemical freeze-out. In heavy-ion collisions at highest energies provided by the LHC, light cluster abundances should follow the statistical model because of low baryon densities. Chemical freeze-out in this domain is correlated with the QCD crossover transition. At low energies, in the nuclear fragmentation region, where the freeze-out interferes with the liquid-gas phase transition, self-energy and Pauli blocking effects are important. We demonstrate that at intermediate energies the chemical freeze-out line correlates with the maximum mass fraction of nuclear bound states, in particular $\alpha$ particles. In this domain, the HADES, FAIR and NICA experiments can give new insights.

    ↳ nucl-thhep-phPLB(2025)·13 citations
23. 23*

    Hyperons during proto-neutron star deleptonization and the emission of dark flavoured particles

    Tobias Fischer🇵🇱 · Jorge Martin Camalich🇪🇸 · Hristijan Kochankovski🇪🇸 · Laura Tolos🇪🇸

    Complementary to high-energy experimental efforts, indirect astrophysical searches of particles beyond the standard model have long been pursued. The present article follows the latter approach and considers, for the first time, the self-consistent treatment of the energy losses from dark flavoured particles produced in the decay of hyperons during a core-collapse supernova (CCSN). To this end, general relativistic supernova simulations in spherical symmetry are performed, featuring six-species Boltzmann neutrino transport, and covering the long-term evolution of the nascent remnant proto-neutron star (PNS) deleptonization for several tens of seconds. A well-calibrated hyperon equation of state (EOS) is therefore implemented into the supernova simulations and tested against the corresponding nucleonic model. It is found that supernova observables, such as the neutrino signal, are robustly insensitive to the appearance of hyperons for the simulation times considered in the present study. The presence of hyperons enables an additional channel for the appearance of dark sector particles, which is considered at the level of the $\Lambda$ hyperon decay. Assuming massless particles that escape the PNS after being produced, these channels expedite the deleptonizing PNS and the cooling behaviour. This, in turn, shortens the neutrino emission timescale. The present study confirms the previously estimated upper limits on the corresponding branching ratios for low and high mass PNS, by effectively reducing the neutrino emission timescale by a factor of two. This is consistent with the classical argument deduced from the neutrino detection associated with SN1987A.

    ↳ astro-ph.HEhep-phnucl-thJCAP(2025)·13 citations
24. 24*

    Exact Results for Scaling Dimensions of Neutral Operators in scalar CFTs

    Oleg Antipin🇭🇷 · Jahmall Bersini🇯🇵 · Francesco Sannino🇮🇹

    We determine the scaling dimension ${\Delta }_n$ for the class of composite operators ${\varphi }^n$ in the $\lambda {\varphi }^4$ theory in $d=4-ϵ$ taking the double scaling limit $n\to \infty$ and $\lambda \to 0$ with fixed $\lambda n$ via a semiclassical approach. Our results resum the leading power of $n$ at any loop order. In the small $\lambda n$ regime we reproduce the known diagrammatic results and predict the infinite series of higher-order terms. For intermediate values of $\lambda n$ we find that ${\Delta }_n/n$ increases monotonically approaching a $(\lambda n{)}^{1/3}$ behavior in the $\lambda n\to \infty$ limit. We further generalize our results to neutral operators in the ${\varphi }^4$ in $d=4-ϵ$, ${\varphi }^3$ in $d=6-ϵ$, and ${\varphi }^6$ in $d=3-ϵ$ theories with $O(N)$ symmetry.

    ↳ hep-thcond-mat.stat-mechhep-lathep-phPRD(2025)·12 citations
25. 25*

    An Infrared On-Shell Action and its Implications for Soft Charge Fluctuations in Asymptotically Flat Spacetimes

    Temple He🇺🇸 · Ana-Maria Raclariu🇩🇪 · Kathryn M. Zurek🇺🇸

    We study the infrared on-shell action of Einstein gravity in asymptotically flat spacetimes, obtaining an effective, gauge-invariant boundary action for memory and shockwave spacetimes. We show that the phase space is in both cases parameterized by the leading soft variables in asymptotically flat spacetimes, thereby extending the equivalence between shockwave and soft commutators to spacetimes with non-vanishing Bondi mass. We then demonstrate that our on-shell action is equal to three quantities studied separately in the literature: $(i)$ the soft supertranslation charge; $(ii)$ the shockwave effective action, or equivalently the modular Hamiltonian; and $(iii)$ the soft effective action. Finally, we compute the quantum fluctuations in the soft supertranslation charge and, assuming the supertranslation parameter may be promoted to an operator, we obtain an area law, consistent with earlier results showing that the modular Hamiltonian has such fluctuations.

    ↳ hep-thgr-qchep-phJ.Phys.A(2025)·21 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.