Wed·May 1, 2024Wednesday·May 1, 2024

1. 01*

   BSMPT v3 A Tool for Phase Transitions and Primordial Gravitational Waves in Extended Higgs Sectors

   Philipp Basler🇩🇪 · Lisa Biermann🇩🇪 · Margarete Mühlleitner🇩🇪 · Jonas Müller🇩🇪 · Rui Santos🇵🇹 · João Viana🇵🇹

   Strong first-order phase transitions (SFOPT) during the evolution of the Higgs potential in the early universe not only allow for the dynamical generation of the observed matter-antimatter asymmetry, they can also source a stochastic gravitational wave (GW) background possibly detectable with future space-based GW interferometers. As SFOPTs are phenomenologically incompatible with the Standard Model (SM) Higgs sector, the observation of GWs from SFOPTs provides an exciting interplay between cosmology and particle physics in the search for new physics. With the C++ code BSMPTv3, we present for the first time a tool that performs the whole chain from the particle physics model to the GW spectrum. Extending the previous versions BSMPTv1 and v2, it traces the phases of beyond-SM (BSM) Higgs potentials and is capable of treating multiple vacuum directions and multi-step phase transitions. During the tracing, it checks for discrete symmetries, flat directions, and electroweak symmetry restoration, and finally reports the transition history. The transition probability from the false to the true vacuum is obtained from the solution of the bounce equation which allows for the calculation of the nucleation, percolation and completion temperatures. The amplitude and characteristic frequencies of the GWs originating from bubble collisions and highly relativistic fluid shells, sound waves and turbulence, are evaluated after the calculation of the thermal parameters at the transition temperature, and finally the signal-to-noise ratio at LISA is provided. The code BSMPTv3 is a powerful self-contained tool that comes more than timely and will be of great benefit for investigations of the vacuum structure of the early universe of not only simple but also complicated Higgs potentials involving several vacuum directions, with exciting applications in the search for new physics.

   hep-phComput.Phys.Commun.(2025)·67 citations
2. 02*

   Coscattering in the Extended Singlet-Scalar Higgs Portal

   Bastián Díaz Sáez🇨🇱 · Jayita Lahiri🇩🇪 · Kilian Möhling🇩🇪

   We study the coscattering mechanism in a simple Higgs portal which add two real singlet scalars to the Standard Model. In this scenario, the lighter scalar is stabilized by a single ${\mathcal{Z}}_2$ symmetry and acts as the dark matter relic, whose freeze-out is driven by conversion processes. The heavier scalar becomes an unstable state which participate actively in the coscattering. We find viable parameter regions fulfilling the measured relic abundance, while evading direct detection and big-bang nucleosynthesis bounds. In addition, we discuss collider prospects for the heavier scalar as a long-lived particle at present and future detectors.

   hep-phJCAP(2024)·14 citations
3. 03*

   CP Violation Problem

   Nicolai Popov (LMU)🇩🇪 · William J. Briscoe (GWU)🇺🇸 · Igor Strakovsky (GWU)🇺🇸

   The strong CP violation problem has a long history emanating from its discovery 60 years ago in the decay of neutral kaons and subsequent experimental and theoretical studies over several decades. We review herein experimental data that observe indirect CP violation of the order of $\sim 10^{-3}$, as well as the discovery of direct CP violation of the order of $\sim 10^{-6}$. Despite improved experimental methods over the past half a century, the original CP violation numbers have remained the same. Verification of the CP violation in the decay of charged kaons was also observed. Data reflecting CP violation in the decays of $B$ and $D$ mesons have become very important and are also discussed in this review. The question of CP violation only with the participation of $s\bar{s}$, $c\bar{c}$, and $b\bar{b}$ quarks in the framework of the Standard Model or beyond it and its small magnitude remains open.

   hep-phhep-exnucl-exnucl-thBraz.J.Phys.(2025)·0 citations
4. 04*

   Large CP violation in charmed baryon decays

   Xiao-Gang He🇨🇳 · Chia-Wei Liu🇨🇳

   This work presents the first detailed numerical predictions of CP violation in antitriplet charmed baryon decays. Adopting the flavor $SU(3{)}_F$ symmetry and the final state re-scattering framework, we relate the CKM-suppressed amplitudes to the leading ones, which are proportional to ${\lambda }_b$ and ${\lambda }_d$, respectively, with ${\lambda }_q=V_{uq}{V}_{cq}^{\ast }$. Larger-than-expected CP violations are found, reaching the order of $10^{-3}$, similar in magnitude to those in $D^0\to {\pi }^{+}{\pi }^{-},K^{+}{K}^{-}$. This opens a promising avenue for observing CP violation in charmed baryon decays and testing the Standard Model.

   hep-phhep-exSci.Bull.(2025)·23 citations
5. 05*

   High-energy neutrino signals from supernova explosions: a new window into dark photon parameter space

   Vsevolod Syvolap🇳🇱 · Oleg Ruchayskiy🇩🇰

   Dark photons, hypothetical feebly interacting massive vector bosons, appear in many extensions of the Standard Model. This study investigates their production and subsequent decay during supernova explosions. We demonstrate that the decay of dark photons, with masses ranging from 200 to 400 MeV, can lead to the emission of neutrinos with energies surpassing those emitted by supernovae. These neutrinos therefore serve as a distinct signal of new physics, allowing for the exploration of previously uncharted regions of the dark photon parameter space and complementing both accelerator-based searches and other astrophysical constraints. The signal is largely unaffected by the specifics of the supernova's temperature and density radial profiles outside the SN core, rendering the prediction both robust and model-independent. Our results indicate that searching for high-energy neutrinos accompanying supernova explosions provides a novel approach to probe physics beyond the Standard Model, including dark photons, heavy neutral leptons, and other feebly interacting particles with masses in the hundreds of MeV range.

   hep-phastro-ph.HEPRD(2024)·8 citations
6. 06*

   Does the Electron EDM Preclude Electroweak Baryogenesis ?

   Yuan-Zhen Li🇨🇳 · Michael J. Ramsey-Musolf🇨🇳 · Jiang-Hao Yu🇨🇳

   Electroweak baryogenesis (EWBG) constitutes a theoretically compelling and experimentally testable mechanism for explaining the origin of the baryon asymmetry of the universe (BAU). New results for the electric dipole moment (EDM) of the electron place significant constraints on the beyond Standard Model CP-violation needed for successful EWBG. Using a specific model illustration, we show how new developments in EWBG quantum transport theory that include CP-violating sources first order in gradients imply more relaxed EDM constraints -- and thereby greater EWBG viability -- than implied by previous approximation formulations. We also illustrate how these developments enable a more realistic treatment of CP-conserving interactions that can also have a decisive impact on the predicted BAU.

   hep-phhep-exnucl-exnucl-thPhys.Lett.B 140503 (2026)·11 citations
7. 07*

   $CP$-violating observables of four-body $B_{(s)}\to (\pi \pi )(K\bar{K})$ decays in perturbative QCD

   Da-Cheng Yan🇨🇳 · Yan Yan🇨🇳 · Zhou Rui🇨🇳

   In this work, we investigate six helicity amplitudes of the four-body $B_{(s)}\to (\pi \pi )(K\bar{K})$ decays in the perturbative QCD (PQCD) approach. The $\pi \pi$ invariant mass spectrum is dominated by the vector resonance $\rho (770)$ together with scalar resonance $f_0(980)$, while the vector resonance $\varphi (1020)$ and scalar resonance $f_0(980)$ are expected to contribute in the $K\bar{K}$ invariant mass range. We extract the two-body branching ratios $\mathcal{B}(B_{(s)}\to \rho \varphi )$ from the corresponding four-body decays $B_{(s)}\to \rho \varphi \to (\pi \pi )(K\bar{K})$. The predicted $\mathcal{B}(B_s^0\to \rho \varphi )$ agrees well with the current experimental data within errors. The longitudinal polarization fractions of the $B_{(s)}\to \rho \varphi$ decays are found to be as large as $90\%$, basically consistent with the previous two-body predictions within uncertainties. In addition, the triple-product asymmetries (TPAs) of the considered decays are also presented for the first time. Since the $B_s^0\to {\rho }^0\varphi \to ({\pi }^{+}{\pi }^{-})(K^{+}{K}^{-})$ decay is induced by both tree and penguin operators, the values of the ${\mathcal{A}}_{\mathrm{dir}}^{\mathrm{CP}}$ and ${\mathcal{A}}_{\text{T-true}}^1$ are calculated to be $(21.8_{-3.3}^{+2.7})\%$ and $(-10.23_{-1.56}^{+1.73})\%$ respectively. While for pure penguin decays $B^0\to {\rho }^0\varphi \to ({\pi }^{+}{\pi }^{-})(K^{+}{K}^{-})$ and $B^{+}\to {\rho }^{+}\varphi \to ({\pi }^{+}{\pi }^0)(K^{+}{K}^{-})$, both the direct $CP$ asymmetries and ``true" TPAs are naturally expected to be zero in the standard model (SM). The ``fake" TPAs requiring no weak phase difference are usually none zero for all considered decay channels. The sizable ``fake" ${\mathcal{A}}_{\text{T-fake}}^1=(-20.92_{-2.80}^{+6.26})\%$ of the $B^0\to {\rho }^0\varphi \to ({\pi }^{+}{\pi }^{-})(K^{+}{K}^{-})$ decay is predicted in the PQCD approach, which provides valuable information on the final-state interactions.Our predictions can be tested by the future experiments.

   hep-phEPJC(2024)·4 citations
8. 08*

   Dihadron helicity correlation in photon-nucleus collisions

   Zhao-Xuan Chen🇨🇳 · Hui Dong🇨🇳 · Shu-Yi Wei🇨🇳

   The helicity correlation of two back-to-back hadrons is a powerful tool that makes it possible to probe the longitudinal spin transfer, $G_{1L}$, in unpolarized hadronic collisions. In this work, we investigate the helicity correlation of back-to-back dihadrons produced in photon-nucleus collisions with both space-like and quasireal photons and explore its potential in understanding the flavor dependence of spin-dependent fragmentation functions. We present helicity amplitudes of partonic scatterings with both virtual and real photons and make numerical predictions for the dihadron helicity correlations at the future Electron Ion Collider experiment and the current RHIC/LHC ultra-peripheral collision experiment. Future experimental measurements can also illuminate the fragmentation function of circularly polarized gluons.

   hep-phhep-exnucl-exPRD(2024)·9 citations
9. 09*

   NMSSM Explanation for Excesses in the Search for Neutralinos and Charginos and a 95 GeV Higgs Boson

   Ulrich Ellwanger🇫🇷 · Cyril Hugonie🇫🇷 · Stephen F. King🇬🇧 · Stefano Moretti🇬🇧

   The observed excesses in the search for neutralinos and charginos by ATLAS and CMS can be fitted simultaneously in the minimal supersymmetric standard model (MSSM) assuming a light higgsino mass, of magnitude less than about 250 GeV, and a compressed higgsino dominated neutralino and chargino spectrum, with $5-10\%$ mass splittings. However, light higgsinos as dark matter would have far too large direct detection cross sections. We consider the next-to-MSSM (NMSSM) with an additional singlino-like lightest supersymmetric particle (LSP) a few GeV below the next-to-lightest supersymmetric particle (NLSP). Sparticles prefer to decay first into the NLSP and remnants from the final decay into the LSP are too soft to contribute to the observed signals. Co-annihilation in the higgsino-sector can generate a relic density in the WMAP/Planck window. The singlino-like LSP has automatically a direct detection cross section below present and future sensitivities: a direct detection signal in the near future would exclude this scenario. The singlet-like Higgs scalar of the NMSSM can have a mass around 95 GeV and signal cross sections in the $b\bar{b}$ channel at LEP and in the $\gamma \gamma$ channel at the LHC compatible with the respective observations.

   hep-phEPJC(2024)·40 citations
10. 10*

    Small Instanton Effects on Composite Axion Mass

    Takafumi Aoki🇯🇵 · Masahiro Ibe🇯🇵 · Satoshi Shirai🇯🇵 · Keiichi Watanabe🇯🇵

    This paper investigates the impact of small instanton effects on the axion mass in composite axion models. In particular, we focus on the Composite Accidental Axion (CAA) models, which are designed to address the axion quality problem, and where the Peccei-Quinn (PQ) symmetry emerges accidentally. In the CAA models, the QCD gauge symmetry is embedded in a larger gauge group at high energy. These models contain small instantons not included in low-energy QCD, which could enhance the axion mass significantly. However, in the CAA models, our analysis reveals that these effects on the axion mass are non-vanishing but are negligible compared to the QCD effects. The suppression of the small instanton effects originates from the global chiral U(1) symmetries which are not broken spontaneously and play a crucial role in eliminating $\theta$-terms in the hidden sectors through anomalies. We find these U(1) symmetries restrict the impact of small instantons in hidden sectors on the axion mass. Our study provides crucial insights into the dynamics within the CAA models and suggests broader implications for understanding small instanton effects in other composite axion models.

    hep-phhep-thJHEP(2024)·10 citations
11. 11*

    Interplay between Vector-like Lepton and Seesaw Mechanism:Oblique Corrections

    Shuyang Han🇨🇳 · Zhaofeng Kang🇨🇳 · Jiang Zhu🇨🇳

    The non-vanishing neutrino mass strongly hints the existence of right-handed neutrinos (RHNs), singlets of the standard model (SM). However, they are highly decoupled from the SM and difficult to probe. In this work, we consider the Majorana RHNs from the type-I seesaw mechanism may well mix with the heavy neutral lepton dwelling in certain vector-like lepton (VLL), thus acquiring a sizable electroweak charge. Such a simple scenario yields many interesting consequences, and the imprint on oblique corrections, well expected from the mass splitting between components of VLL by virtue of VLL-RHN mixing, is our focus here. We analytically calculate the Peskin-Takeuchi parameters S, T and U with full details, carefully treating the Majorana loop to obtain the self consistent expressions free of divergence. Then, we constrain on the VLL-RHN system which only gives a sizable $T$ parameter using the PDG-2021 data and CDF-II data, separately, by imposing $T\lesssim \mathcal{O}(0.1)$. It is found that for the RHN and VLL below the TeV scale, with a properly large mixing, stands in the frontier of the electroweak precision test such as W-boson mass.

    hep-phJHEP(2024)·1 citation
12. 12*

    Soft pattern of gravitational Rutherford scattering from heavy target mass expansion

    Yu Jia🇨🇳 · Jichen Pan🇨🇳 · Jia-Yue Zhang🇨🇳

    We investigate the soft behavior of the tree-level Rutherford scattering processes mediated via $t$-channel one-graviton exchange. We consider two types of Rutherford scattering processes, {\it e.g.}, a low-energy massless structureless projectile (up to spin-$1$) hits a static massive composite particle carrying various spins (up to spin-$2$), and a slowly-moving light projectile hits a heavy static composite target. The unpolarized cross sections in the first type are found to exhibit universal forms at the first two orders in $1/M$ expansion, yet differ at the next-to-next-to-leading order, though some terms at this order still remain universal or depend on the target spin in a definite manner. The unpolarized cross sections in the second type are universal at the lowest order in projectile velocity expansion and through all orders in $1/M$, independent of the spins of both projectile and target. The universality partially breaks down at relative order-$v^2/M^2$, albeit some terms at this order still depend on the target spin in a specific manner.

    hep-phgr-qcCPC(2026)·0 citations
13. 13*

    Impact of recent updates to neutrino oscillation parameters on the effective Majorana neutrino mass in 0$\nu \beta \beta$ Decay

    Dongming Mei🇺🇸 · Kunming Dong🇺🇸 · Austin Warren🇺🇸 · Sanjay Bhattarai🇺🇸

    We investigate how recent updates to neutrino oscillation parameters and the sum of neutrino masses influence the sensitivity of neutrinoless double-beta (0$\nu \beta \beta$) decay experiments. Incorporating the latest cosmological constraints on the sum of neutrino masses and laboratory measurements on oscillations, we determine the sum of neutrino masses for both the normal hierarchy (NH) and the inverted hierarchy (IH). Our analysis reveals a narrow range for the sum of neutrino masses, approximately 0.06 eV/c${}^2$ for NH and 0.102 eV/c${}^2$ for IH. Utilizing these constraints, we calculate the effective Majorana masses for both NH and IH scenarios, establishing the corresponding allowed regions. Importantly, we find that the minimum neutrino mass is non-zero, as constrained by the current oscillation parameters. Additionally, we estimate the half-life of 0$\nu \beta \beta$ decay using these effective Majorana masses for both NH and IH. Our results suggest that upcoming ton-scale experiments will comprehensively explore the IH scenario, while 100-ton-scale experiments will effectively probe the parameter space for the NH scenario, provided the background index can achieve 1 event/kton-year in the region of interest.

    hep-phnucl-exphysics.data-anPRD(2024)·6 citations
14. 14*

    On the inefficiency of fermion level-crossing under the parity-violating spin-2 gravitational field

    Kohei Kamada🇯🇵 · Jun'ya Kume🇮🇹

    Gravitational chiral anomaly connects the topological charge of spacetime and the chirality of fermions. It has been known that the chirality is carried by the particles (or the excited states) and also by vacuum. While the gravitational anomaly equation has been applied to cosmology, distinction between these two contributions has been rarely discussed. In the study of gravitational leptogenesis, for example, lepton asymmetry associated with the chiral gravitational waves (GWs) sourced during inflation is evaluated only by integrating the anomaly equation. This approach, however, does not reveal how these two contributions are distributed in this scenario. Meanwhile, the dominance of vacuum contribution is observed in some specific types of Bianchi spacetime with parity-violating gravitational fields. One may wonder whether such a vacuum dominance takes place also in the system with chiral GWs around the flat background, which is more suitable for application to realistic cosmology. In this work, we apply an analogy between U(1) electromagnetism and the weak gravity to the spacetime that captures the characteristics of the one considered in the gravitational leptogenesis. With this approach, we try to obtain intuitive understanding of the fermion chirality generation under the parity-violating spin-2 gravitational field. By assuming the emergence of Landau level-like dispersion relation in our setup, we observe that spin-2 nature seems to make the level-crossing inefficient, indicating that the chrial charge is likely to accumulate in the vacuum. On this basis, phenomenological implications for gravitational leptogenesis are discussed.

    hep-phastro-ph.COgr-qchep-thJHEP(2025)·2 citations
15. 15*

    The Width of an Electron-Capture Neutrino Wave Packet

    B.J.P. Jones🇺🇸 · E Marzec🇺🇸 · J. Spitz🇺🇸

    We discuss the size of an electron neutrino wave packet emerging from an electron capture decay using the formalism of open quantum systems. This quantitative result is based on methodology that we have previously used to predict the width of an electron antineutrino wave packet from a beta-decaying nucleus, adapted for the different initial states in electron capture and beta decay. These predictions are now becoming relevant to experimental probes of the neutrino width, for example indirectly through precision spectroscopic studies of the nuclear recoil. We provide a translation between a recent Beryllium Electron capture in Superconducting Tunnel junctions Experiment (BeEST) measurement of the daughter nuclear recoil spectrum from ${}^7\mathrm{Be}$ electron capture decay ($e^{-}+{}^7\mathrm{Be}\to {}^7\mathrm{Li}+{\nu }_{\mathrm{e}}$) and a constraint on the outgoing neutrino width. According to our analysis, the direct limit on the neutrino wave packet width from electron capture decay using the recent BeEST result should map to ${\sigma }_{\nu ,x}>6.2\mathrm{pm}$. We determine that a hard upper limit on the wave packet width exists at ${\sigma }_{\nu ,x}\sim 2.7\mathrm{nm}$, based on the relative momentum between the electron and nucleus. However, we find that the localization is most likely driven by the embedding of the decaying atom in the tantalum crystal lattice resulting in a width scale of approximately ${\sigma }_{\nu ,x}\sim 10$~pm, motivated by data from X-ray diffraction and M$\ddot{\mathrm{o}}$ssbauer spectroscopy, which lies intriguingly close to the current bound.

    hep-phnucl-th5 citations
16. 16*

    Cosmic Ray-Boosted Dark Matter at IceCube

    Christopher Cappiello🇨🇦 · Qinrui Liu🇨🇦 · Gopolang Mohlabeng🇺🇸 · Aaron C. Vincent🇨🇦

    Cosmic ray (CR) upscattering of dark matter is considered as one of the most straightforward mechanisms to accelerate ambient dark matter, making it detectable at high threshold, large volume experiments. In this work, we revisit CR upscattered dark matter signals at the IceCube detector, focusing on lower energy data than was considered before. We consider both scattering with electrons and nuclei. In the latter, we include both elastic and deep-inelastic scattering computations. As concrete examples, we consider two benchmark models; Fermion dark matter with vector and scalar mediators. We compare our model projections with the most current constraints and show that the IceCube detector can detect CR-boosted dark matter especially with masses below $\sim$ 100 keV when scattering with electrons and $\sim$ MeV in the nucleon scattering case.

    hep-phastro-ph.COastro-ph.HEPRD(2024)·24 citations
17. 17*

    Mass from Nothing

    Paul Romatschke🇺🇸 · Chun-Wei Su🇺🇸 · Ryan Weller🇺🇸

    We study the Abelian Higgs model with multiple scalar fields, but without mass terms. Solving the model non-perturbatively order-by-order in the number of scalar fields, we find that radiative corrections generate masses for the scalar and gauge boson, without spontaneous symmetry breaking. The mass scales are set by the $\Lambda$-parameter of the electroweak running coupling, thereby naturally avoiding the hierarchy problem. No part of our calculation employs a weak-coupling expansion, and we find that the perturbative vacuum is metastable, and hence must decay to the stable non-perturbative vacuum of the theory, which we identify. Although the field content of our Lagrangian is standard, our results predict the existence of two heavy scalar resonances in addition to the Higgs. We believe that these predicted resonances will ultimately allow experimentalists to discriminate between our method and standard solutions of the Higgs model.

    hep-phhep-thnucl-thPRD(2024)·10 citations
18. 18*

    Accelerated cosmic expansion, mass creation, and the QCD axion

    Kristjan Müürsepp🇪🇪 · Enrico Nardi🇮🇹 · Clemente Smarra🇮🇹

    We propose a mechanism in which the current acceleration of cosmic expansion is driven by continuous creation of energy density ${\rho }_b$ for a certain field ${\phi }_b$. We accordingly modify Einstein equation, derive modified Friedmann equations and analyze the regimes in which cosmic acceleration occurs. The creation process requires ${\rho }_b\ne 0$ as initial condition, which we enforce by identifying ${\phi }_b$ with the axion of a hidden gauge group that confined in recent cosmological times, leading to a level crossing between ${\phi }_b$ and the QCD axion, which is assumed to comprise dark matter. The conversion of a small fraction of QCD axions into ${\phi }_b$ shortly before matter-dark energy equality generates the initial ${\rho }_b$ needed to trigger the creation process and offers a solution to the coincidence puzzle.

    hep-phastro-ph.CO13 citations
19. 19*

    How to rule out $(g-2{)}_{\mu }$ in $U(1{)}_{L_{\mu }-L_{\tau }}$ with White Dwarf Cooling

    Patrick Foldenauer🇪🇸 · Jaime Hoefken Zink🇮🇹

    In recent years, the gauge group $U(1{)}_{L_{\mu }-L_{\tau }}$ has received a lot of attention since it can, in principle, account for the observed excess in the anomalous muon magnetic moment $(g-2{)}_{\mu }$, as well as the Hubble tension. Due to unavoidable, loop-induced kinetic mixing with the SM photon and $Z$, the $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge boson $A^{\prime }$ can contribute to stellar cooling via decays into neutrinos. In this work, we perform for the first time an \textit{ab initio} computation of the neutrino emissivities of white dwarf stars due to plasmon decay in a model of gauged $U(1{)}_{L_{\mu }-L_{\tau }}$. A key result is that current observations of the early-stage white dwarf neutrino luminosity at the 30\% level exclude previously allowed regions of the parameter space favoured by a simultaneous explanation of the $(g-2{)}_{\mu }$ and $H_0$ anomalies. In this work, we present the relevant white dwarf cooling limits over the entire $A^{\prime }$ mass range. In particular, we have performed a rigorous computation of the luminosities in the resonant regime, where the $A^{\prime }$ mass is comparable to the white dwarf plasma frequencies.

    hep-phJHEP(2024)·14 citations
20. 20*

    Flavor Phenomenology of Light Dark Vectors

    Jordi Folch Eguren🇩🇪 · Sophie Klingel🇩🇪 · Emmanuel Stamou🇩🇪 · Mustafa Tabet🇩🇪 · Robert Ziegler🇩🇪

    Light dark matter with flavor-violating couplings to fermions may be copiously produced in the laboratory as missing energy from decays of SM particles. Here we study the effective Lagrangian of a light dark vector with generic dipole or vector couplings. We calculate the resulting two-body decay rates of mesons, baryons and leptons as a function of the dark vector mass and show that existing experimental limits probe UV scales as large as $10^{12}\mathrm{GeV}$. We also derive the general RGEs in order to constrain the flavor-universal UV scenario, where all flavor violation arises radiatively proportional to the CKM matrix.

    hep-phJHEP(2024)·14 citations
21. 21*

    Updated observational constraints on spatially-flat and non-flat $\Lambda$CDM and XCDM cosmological models

    Javier de Cruz Perez🇪🇸 · Chan-Gyung Park🇰🇷 · Bharat Ratra🇺🇸

    We study 6 LCDM models, with 4 allowing for non-flat geometry and 3 allowing for a non-unity lensing consistency parameter $A_L$. We also study 6 XCDM models with a dynamical dark energy density X-fluid with equation of state $w$. For the non-flat models we use two different primordial power spectra, Planck $P(q)$ and new $P(q)$. These models are tested against: Planck 2018 CMB power spectra (P18) and lensing potential power spectrum (lensing), and an updated compilation of BAO, SNIa, $H(z)$, and $f{\sigma }_8$ data [non-CMB data]. P18 data favor closed geometry for the LCDM and XCDM models and $w<-1$ (phantom-like dark energy) for the XCDM models while non-CMB data favor open geometry for the LCDM models and closed geometry and $w>-1$ (quintessence-like dark energy) for the XCDM models. When P18 and non-CMB data are jointly analyzed there is weak evidence for open geometry and moderate evidence for quintessence-like dark energy. Regardless of data used, $A_L>1$ is always favored. The XCDM model constraints obtained from CMB data and from non-CMB data are incompatible, ruling out the 3 $A_L=1$ XCDM models at $>3\sigma$. In the 9 models not ruled out, for the P18+lensing+non-CMB data set we find little deviation from flat geometry and moderate deviation from $w=-1$. In all 6 non-flat models (not ruled out), open geometry is mildly favored, and in all 3 XCDM+$A_L$ models (not ruled out) quintessence-like dark energy is moderately favored (by at most $1.6\sigma$). In the $A_L=1$ non-flat LCDM cases, we find for P18+lensing+non-CMB data ${\Omega }_k=0.0009\pm 0.0017$ [$0.0008\pm 0.0017$] for the Planck [new] $P(q)$ model, favoring open geometry. The flat LCDM model remains the simplest (largely) observationally-consistent cosmological model. Our cosmological parameter constraints obtained for the flat LCDM model (and other models) are the most restrictive results to date (Abridged).

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2024)·43 citations
22. 22*

    Neutrinos in Cosmology

    Eleonora Di Valentino🇬🇧 · Stefano Gariazzo🇮🇹 · Olga Mena🇪🇸

    Neutrinos are the least known particle in the Standard Model of elementary particle physics. They play a crucial role in cosmology, governing the universe's evolution and shaping the large-scale structures we observe today. In this chapter, we review crucial topics in neutrino cosmology, such as the neutrino decoupling process in the very early universe. We shall also revisit the current constraints on the number of effective relativistic degrees of freedom and the departures from its standard expectation of 3. Neutrino masses represent the very first departure from the Standard Model of elementary particle physics and may imply the existence of new unexplored mass generation mechanisms. Cosmology provides the tightest bound on the sum of neutrino masses, and we shall carefully present the nature of these constraints, both on the total mass of the neutrinos and on their precise spectrum. The ordering of the neutrino masses plays a major role in the design of future neutrino mass searches from laboratory experiments, such as neutrinoless double beta decay probes. Finally, we shall also present the futuristic perspectives for an eventual direct detection of cosmic, relic neutrinos.

    ↳ astro-ph.COhep-ph34 citations
23. 23*

    Trace conservation laws in $T^2/Z_m$ orbifold gauge theories

    Kota Takeuchi🇯🇵 · Tomohiro Inagaki🇯🇵

    Gauge theory compactified on an orbifold is defined by gauge symmetry, matter contents, and boundary conditions. There are equivalence classes (ECs), each of which consists of physically equivalent boundary conditions. We propose the powerful necessary conditions, trace conservation laws (TCLs), which achieve a sufficient classification of ECs in U(N) and SU(N) gauge theories on $T^2/Z_m$ orbifolds $(m=2,3,4,6)$. The TCLs yield the equivalent relations between the diagonal boundary conditions without relying on an explicit form of gauge transformations. The TCLs also show the existence of off-diagonal ECs, which consist only of off-diagonal matrices, on $T^2/Z_4$ and $T^2/Z_6$. After the sufficient classification, the exact numbers of ECs are obtained.

    ↳ hep-thhep-phPTEP(2024)·2 citations
24. 24*

    Gauge invariant discretization of Chern-Simons couplings

    Kohta Hatakeyama🇯🇵 · Matsuo Sato🇯🇵 · Gota Tanaka🇯🇵

    We discretize Chern-Simons couplings in gauge invariant way. We obtain (p+q)-forms representing Chern-Simons couplings on (p + q)-simplexes from wedge products of p- and q-forms on p- and q-simplexes, respectively, where p- and q-simplexes form (p+q)-simplexes by having a common vertex. We show that the Chern-Simons couplings on simplicial complexes reduce to Chern-Simons couplings on the manifolds in a continuum limit. Moreover, we prove that a typical discretized Chern-Simons term that has the Chern-Simons coupling is gauge invariant.

    ↳ hep-lathep-phhep-th2 citations
25. 25*

    Toward the application of large-$N$ deconfinement to SU(3) QCD

    Hiromasa Watanabe🇯🇵

    It is generally known for $\mathrm{U}(N)$ gauge theory at finite temperature that phase transitions are manifested by taking the large-$N$ limit. Since the large-$N$ theory undergoes two thermodynamic phase transitions, a nontrivial intermediate phase can be realized in addition to the phases classified as the conventional confined and deconfined phases. In this talk, we discuss that a similar picture can be applied to QCD with $N=3$. In particular, we analyze the gauge configurations of lattice QCD calculations involving dynamical quarks and show the results of an analysis of the deviation due to finite-temperature effects from the Haar randomness expected at zero temperature in $\mathrm{SU}(N)$ gauge theory, using physical pictures suggested by the large-$N$ theory.

    ↳ hep-thhep-lathep-phnucl-thPoS(2024)·0 citations
26. 26*

    Intrinsic negative magnetoresistance from the chiral anomaly of multifold fermions

    F. Balduini🇨🇭 · A. Molinari🇨🇭 · L. Rocchino🇨🇭 · V. Hasse🇩🇪 · C. Felser🇩🇪 · M. Sousa🇨🇭 · C. Zota🇨🇭 · H. Schmid🇨🇭 · A. G. Grushin🇫🇷 · B. Gotsmann🇨🇭

    The chiral anomaly, a hallmark of chiral spin-1/2 Weyl fermions, is an imbalance between left- and right-moving particles that underpins both high and low energy phenomena, including particle decay and negative longitudinal magnetoresistance in Weyl semimetals. The discovery that chiral crystals can host higher-spin generalizations of Weyl quasiparticles without high-energy counterparts, known as multifold fermions, raises the fundamental question of whether the chiral anomaly is a more general phenomenon. Answering this question requires materials with chiral quasiparticles within a sizable energy window around the Fermi level, that are unaffected by trivial extrinsic effects such as current jetting. Here we report the chiral anomaly of multifold fermions in CoSi, which features multifold bands within about 0.85 eV around the Fermi level. By excluding current jetting through the squeezing test, we measure an intrinsic, longitudinal negative magnetoresistance. We develop the semiclassical theory of magnetotransport of multifold fermions that shows that the negative magnetoresistance originates in their chiral anomaly, despite a sizable and detrimental orbital magnetic moment contribution, previously unaccounted for. A concomitant nonlinear Hall effect supports the multifold-fermion origin of magnetotransport. Our work confirms the chiral anomaly of higher-spin generalizations of Weyl fermions, currently inaccessible outside the solid-state.

    ↳ cond-mat.mes-hallcond-mat.otherhep-phNature Commun.(2024)·17 citations
27. 27*

    Quintom cosmology and modified gravity after DESI 2024

    Yuhang Yang🇨🇳 · Xin Ren🇨🇳 · Qingqing Wang🇨🇳 · Zhiyu Lu🇨🇳 · Dongdong Zhang🇨🇳 · Yi-Fu Cai🇨🇳 · Emmanuel N. Saridakis🇬🇷

    We reconstruct the cosmological background evolution under the scenario of dynamical dark energy through the Gaussian process approach, using the latest Dark Energy Spectroscopic Instrument (DESI) baryon acoustic oscillations (BAO) combined with other observations. Our results reveal that the reconstructed dark-energy equation-of-state (EoS) parameter $w(z)$ exhibits the so-called quintom-B behavior, crossing $-1$ from phantom to quintessence regime as the universe expands. We investigate under what situation this type of evolution could be achieved from the perspectives of field theories and modified gravity. In particular, we reconstruct the corresponding actions for $f(R)$, $f(T)$, and $f(Q)$ gravity, respectively. We explicitly show that, certain modified gravity can exhibit the quintom dynamics and fit the recent DESI data efficiently, and for all cases the quadratic deviation from the $\Lambda$CDM scenario is mildly favored.

    ↳ astro-ph.COgr-qchep-phhep-thSci.Bull.(2024)·125 citations
28. 28*

    AGN constraints on neutrino-dark matter scattering

    James M. Cline🇨🇦

    The IceCube collaboration has identified neutrinos of energy $\sim 10-100$ TeV from the blazar TXS 0506+056 and the active galaxy NGC 1068, which must have traveled through a dense dark matter spike surrounding the supermassive black holes that power the galactic nuclei. We use this to set new constraints on dark matter-neutrino scattering, and interpret the results in terms of a dark photon that couples to baryon minus lepton number.

    ↳ astro-ph.HEhep-ph0 citations
29. 29*

    Prospects for weighing neutrinos in interacting dark energy models using joint observations of gravitational waves and $\gamma$-ray bursts

    Lu Feng🇨🇳 · Tao Han🇺🇸 · Jing-Fei Zhang🇺🇸 · Xin Zhang🇺🇸

    Cosmological observations can be used to weigh neutrinos, but this method is model-dependent, with results relying on the cosmological model considered. If we consider interactions between dark energy and dark matter, the neutrino mass constraints differ from those derived under the standard model. On the contrary, gravitational wave (GW) standard siren observations can measure absolute cosmological distances, helping to break parameter degeneracies inherent in traditional cosmological observations, thereby improving constraints on neutrino mass. This paper examines the constraints on neutrino mass within interacting dark energy (IDE) models and explores how future GW standard siren observations could enhance these results. For multi-messenger GW observations, we consider the joint observations of binary neutron star mergers by third-generation ground-based GW detectors and short $\gamma$-ray burst observations by missions similar to the THESEUS satellite project. Using current cosmological observations (CMB+BAO+SN), we obtain an upper limit on the neutrino mass in the IDE models of 0.15 (or 0.16) eV. With the inclusion of GW data, the upper limit on the neutrino mass improves to 0.14 eV. This indicates that in the context of IDE models, the improvement in neutrino mass constraints from GW observations is relatively limited. However, GW observations significantly enhance the constraints on other cosmological parameters, such as matter density parameter, the Hubble constant, and coupling strength between dark energy and dark matter.

    ↳ astro-ph.COgr-qchep-phCPC(2024)·20 citations
30. 30*

    The Unreasonable Effectiveness of the Tunneling Potential

    J.R. Espinosa🇪🇸

    The Tunneling Potential Formalism was introduced to calculate the tunneling actions that control vacuum decay as an alternative to the standard Euclidean Formalism. The new approach sets the problem as a simple variational problem in field space with decay described by a tunneling potential function $V_t$ that extremizes a simple action functional $S[V_t]$ and has a number of appealing properties that have been presented elsewhere. In this note I discuss several instances in which this $V_t$ approach seems to give more than one would have expected a priori, as the following: the $V_t$ describing the decay is a minimum of the new action $S[V_t]$ rather than a saddle point; the decay of AdS, dS or Minkowski vacua are governed by a unique universal $S[V_t]$ which also gives the Hawking-Moss instanton in the appropriate limit; physically relevant solutions beyond the Coleman-De Luccia (CdL) bounce, like pseudo-bounces or bubbles of nothing (BoNs), show up in a straightforward way as generalizations of the CdL bounce, with the correct boundary conditions; in cases for which the Euclidean action calculation requires the inclusion of particular boundary terms (like for BoNs or for the decay of AdS maxima above the Breitenlohner-Freedman bound) $S[V_t]$ gives the correct result without the need of including any boundary term.

    ↳ hep-thgr-qchep-phPoS(2024)·3 citations
31. 31*

    Scalar perturbations from inflation in the presence of gauge fields

    R. Durrer🇨🇭 · R. von Eckardstein🇩🇪 · Deepen Garg🇨🇭 · K. Schmitz🇩🇪 · O. Sobol🇩🇪 · S. Vilchinskii🇨🇭

    We study how Abelian-gauge-field production during inflation affects scalar perturbations in the case when the gauge field interacts with the inflaton directly (by means of generic kinetic and axial couplings) and via gravity. The homogeneous background solution is defined by self-consistently taking into account the backreaction of the gauge field on the evolution of the inflaton and the scale factor. For the perturbations on top of this background, all possible scalar contributions coming from the inflaton, the metric, and the gauge field are considered. We derive a second-order differential equation for the curvature perturbation, $\zeta$, capturing the impact of the gauge field, both on the background dynamics and on the evolution of scalar perturbations. The latter is described by a source term in the $\zeta$ equation, which is quadratic in the gauge-field operators and leads to non-Gaussianities in the curvature perturbations. We derive general expressions for the induced scalar power spectrum and bispectrum. Finally, we apply our formalism to the well-known case of axion inflation without backreaction. Numerical results show that, in this example, the effect of including metric perturbations is small for values of the gauge-field production parameter $\xi >3$. This is in agreement with the previous results in the literature. However, in the region of smaller values, $\xi \lesssim 2$, our new results exhibit order-of-unity deviations when compared to previous results.

    ↳ astro-ph.COgr-qchep-phPRD(2024)·30 citations
32. 32*

    Role of local anisotropy in hybrid stars

    Luiz L. Lopes🇧🇷 · H. C. Das🇮🇳

    Using the Bower-Liang model, we discuss how pressure anisotropies affect the microscopic and macroscopic properties of hybrid stars. We find that anisotropies affect the maximum mass, central density, and radius of the canonical stars. Anisotropies also affect the minimum neutron star mass that presents quarks in their core, as well as the total amount of quarks for the maximally massive stars. We also confront our results with standard constraints, such as the radius and the tidal parameter of the canonical star, as well as the mass and radius of the PSR J0740+6620 pulsar. We observe that moderate values for anisotropies could fulfill these constraints simultaneously. On the other hand, within more extreme degrees of anisotropies, more speculative constraints such as black widow pulsars PSR J0952-0607 and the mass-gap object in the GW190814 event can be explained as hybrid stars. We also investigate the role of anisotropies in the neutron stars' moment of inertia.

    ↳ astro-ph.HEgr-qchep-phnucl-thEPJC(2024)·7 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.