Thu·Oct 24, 2024Thursday·October 24, 2024

1. 01*

   Supernova bounds on new scalars from resonant and soft emission

   Edward Hardy🇬🇧 · Anton Sokolov🇬🇧 · Henry Stubbs🇬🇧

   We study supernova cooling constraints on new light scalars that mix with the Higgs, couple only to nucleons, or couple only to leptons. We show that in all these cases scalars with masses smaller than the plasma frequency in the supernova core are efficiently produced by resonant mixing with the in-medium longitudinal degree of freedom of the photon. The resulting bounds are free from uncertainties associated to the rate of emission of the scalar in nucleon-nucleon scatterings, which would otherwise badly affect the Higgs-mixed and nucleophilic scenarios. Heavier scalars that mix with the Higgs or couple only to nucleons are mostly produced by nucleon bremsstrahlung, and we obtain a conservative approximation for the corresponding rate using a soft theorem. We also analyse the impact of different supernova profiles, nucleon degeneracy, trapping and scalar decays on the constraints.

   hep-phJHEP(2025)·34 citations
2. 02*

   Analysis of identified-hadron spectra from fixed-target $\mathbf{p}$-A collisions and the nature of the Cronin effect

   Thomas A. Trainor🇺🇸

   In this study fixed-target spectra obtained by the Chicago-Princeton (C-P) collaboration at Fermilab in the mid seventies are analyzed with a two-component spectrum model (TCM) that has been applied successfully to a number of collision systems at the RHIC and LHC in the past. It is from C-P data that the Cronin effect was first inferred. TCM analysis leads to factorization of collision-energy and target A dependences. Over the energy range of C-P data energy dependence is restricted to model-function shapes on $p_t$ whereas A dependence is restricted to particle densities for three hadron species and their antiparticles. A dependence for soft and hard components varying separately as power laws $A^{{\alpha }_s}$ and $A^{{\alpha }_h}$ with fixed exponents is a central finding of this study. The trends $A^{\alpha (p_t)}$ inferred by the C-P collaboration resulted from treating spectra as monolithic which confuses the distinct $p_t$ (model functions) and A (particle densities) dependences. The Cronin effect resulting from that confusion is easily explained in a TCM context. Power-law trends for pions at 25 GeV are quantitatively compatible with trends at LHC energies. The relation of exponents $a_s$ and $a_h$ to $p$-A centrality is examined in detail. A Glauber model of $p$-A centrality seems invalid.

   hep-ph0 citations
3. 03*

   Exploring Particle Production and Thermal-Like Behavior through Quantum Entanglement

   Alek Hutson🇺🇸 · Rene Bellwied🇺🇸

   Recent studies have shown a potential correlation between the entanglement of initial state partons in elementary particle collisions, as conceptualized by contemporary quantum and particle theory, and the final state multiplicity distribution of hadrons produced in experiments like those at the Large Hadron Collider (LHC). It has been proposed that this relation between states can be demonstrated in a measurement of entropy. By showing equality between entanglement entropy in the initial state and thermodynamic entropy in the final state, we hope to demonstrate that not only is entanglement the driving mechanism behind matter generation, but also the thermal-like behavior seen in high energy particle collisions.

   hep-phhep-thnucl-exnucl-thUniverse(2026)·2 citations
4. 04*

   Overview on the theory and phenomenology of generalized parton distributions

   Jian-Wei Qiu🇺🇸 · Zhite Yu🇺🇸

   We give a brief overview on the theory and phenomenology of generalized parton distributions (GPDs), including the recently developed framework of single-diffractive hard exclusive process for matching GPDs to experimental observables. We concentrate on the extraction of GPDs from experimental processes, especially on the challenges and potential solutions regarding the separation of different GPDs and the extraction of $x$-dependence of GPDs, which is critically important for constructing the tomographic images and matching the $x$-moments of GPDs to various emergent hadron properties.

   hep-phnucl-exnucl-thPoS(2024)·1 citation
5. 05*

   Polarization study of the P-wave charmonium radiative decay into a light vector meson at $e^{+}{e}^{-}$ collider experiment

   Yong-Qing Chen🇨🇳 · Peng-Cheng Hong🇨🇳 · Zhuo Chen🇨🇳 · Wei Shan🇨🇳 · Wei-Min Song🇨🇳

   In this work, a formalism is presented for the helicity amplitude analysis of the decays $\psi (2S)\to {\gamma }_1{\chi }_{cJ},{\chi }_{cJ}\to {\gamma }_{2}V(V={\rho }^0,\varphi ,\omega )$~(the subscript 1,2 is used to distinguish the two radiative photons), and the polarization expressions of the P-wave charmonia ${\chi }_{cJ}$ and the vector mesons ${\rho }^0,\varphi ,\omega$ for experimental measurements at Electron-Positron Collider. In addition, we derive the formulae of the angular distributions of the ${\chi }_{c1,2}\to \gamma V$ to extract the degree of transverse polarization $P_T$ of $e^{+}{e}^{-}$ pairs with symmetric beam energy as well as the ratios of two helicity amplitudes $x$ (in ${\chi }_{c1}$ decays) and $x,y$ (in ${\chi }_{c2}$ decays) representing the relative magnitudes of transverse to longitudinal polarization amplitude, and validate it by performing the Monte Carlo simulation. Finally, the statistical sensitivity of $P_T$, $x$ and $y$ are estimated based on the large $\psi (2S)$ data samples collected at the current and proposed future $e^{+}{e}^{-}$ collider experiment.

   hep-phhep-exCPC(2025)·1 citation
6. 06*

   A step towards estimation of the neutral-hadron size: the gravitational mass radius of pi0 meson in a relativistic theory of composite particles

   A.F. Krutov🇷🇺 · V.E. Troitsky🇷🇺

   We extend our nonperturbative essentially relativistic approach, elaborated previously, to perform an approximate estimation of the size of pi0 meson. We present detailed argumentation for choosing the mass mean square radius (MSR) for this purpose. Its value calculated in our approach, using three model quark-antiquark wave functions in pion, is (0.5-0.53) fm. The neutral-pion electromagnetic form factor is zero in accordance with the charge-conjugation symmetry. We demonstrate ambiguities encountered when using standard definitions of mechanical MSR for the size. We discuss MSRs obtained in various approaches and their comparison with each other and with our results.

   hep-phPRD(2025)·8 citations
7. 07*

   Laser induced Compton Scattering to Dark Photon or Axion-like Particle

   Kai Ma🇨🇳 · Tong Li🇨🇳

   The laser of an intense electromagnetic field provides an important tool to study the strong-field particle physics. The nonlinear Compton scattering was observed in the collision of an ultra-relativistic electron beam with a laser pulse in 1990s. The precision measurement of the nonlinear Compton scattering shines the light on the studies of strong-field QED and nonlinear effects in QED. In this work, we propose to produce new massive particles through the nonlinear Compton scattering in the presence of a high intense laser field. We take dark photon or axion-like particle as illustrative new particle. Compared with other collider and beam dump experiments, the laser induced process provides a complementary and competitive search of new invisible particles lighter than 1 MeV.

   hep-phhep-exPRD(2025)·9 citations
8. 08*

   New Physics Off the $Z$-Pole: $e^{+}{e}^{-}\to f\bar{f}$ at Future Lepton Colliders

   Shao-Feng Ge🇨🇳 · Zhuoni Qian🇨🇳 · Michael J. Ramsey-Musolf🇨🇳 · Jia Zhou🇺🇸

   We explore the prospects for probing new physics (NP) beyond the Standard Model (SM) at future lepton colliders through precision measurements of $e^{+}{e}^{-}\to f\bar{f}$ observables off the $Z$ resonance. We consider interference between SM contributions and those arising from dimension-6, four-fermion effective operators that encode the effects of NP, yielding a linear dependence on the latter. This linear dependence in general increases with magnitude of the collision energy offset from the $Z$ pole. We consider a variety of asymmetries in order to enhance the NP-sensitivity while reducing experimental systematic and theoretical, SM uncertainties: an inclusive above and below $Z$-resonance total cross section asymmetry ($A_{\sigma }$) as well as the conventional forward-backward ($A_{\mathrm{FB}}$) and polarization ($A_{\mathrm{pol}}$) asymmetries. Based on projected statistical uncertainties at the Circular Electron-Positron Collider (CEPC), we find that t measurement of $A_{\sigma }$ could extend the sensitivity to the NP mass scale by as much as a factor of $\sim 7$ compared to the present reach obtained with the CERN Large Electron Positron Collider. Inclusion of projected systematic theoretical SM uncertainties substantially reduce this sensitivity gain. For $A_{\mathrm{FB}}$, inclusion of experimental systematic uncertainties has a marginal impact on the gain in NP reach, whereas SM theoretical uncertainties remain a significant barrier to realizing the full NP sensitivity. Analogous conclusions apply to the CERN Future Circular Collider (FCC-ee) and International Linear Collider (ILC).

   hep-phJHEP(2025)·9 citations
9. 09*

   Exclusive $c\to u\gamma$ transitions of $B_c$ meson

   Nicola Losacco🇮🇹

   We study the rare decays of the $B_c$ meson induced by the flavour changing neutral current $c\to u\gamma$ transition. In the Standard Model they are strongly suppressed by the Glashow-Iliopoulos-Maiani mechanism, therefore they are sensitive to new physics. The difficulty is to get rid of long-distance contributions. We study such effects in radiative $B_c$ transitions both to $B^{\ast }$ and to the axial-vector $B_1^{\prime }$ meson.

   hep-phEPJ Web Conf.(2024)·0 citations
10. 10*

    Attenuation of Boosted Dark Matter in Two Component Dark Matter Scenario

    Nilanjana Kumar🇮🇳 · Gaadha Lekshmi🇮🇳

    Boosted dark matter constitutes a small fraction of the total dark matter in the Universe, with mass ranging from eV to MeV and often exhibiting (semi)relativistic velocity. Hence the likelihood of detecting boosted dark matter in Earth-based direct detection experiments is relatively high. There is more than one explanation for the origin of the boosted dark matter including the two-component dark matter models where the heavier dark matter species(dominant) annihilates to nearly monoenergetic light dark matter particles (subdominant) in the galactic halo. If the dominant dark matter species is heavier (MeV-GeV), the subdominant light dark matter achieves (semi)relativistic velocity or {\it boost}. These boosted dark matter particles suffer from scattering with electrons and nuclei while crossing the atmosphere and the Earth's crust before reaching underground experiments and hence the kinetic energy of the dark matter is attenuated. In the two-component dark matter framework, we examine how the boost of the dark matter influences the attenuation of kinetic energy across a broad spectrum of dark matter masses. We perform a detailed study at various DM-electron and DM-nucleus cross sections including the effect of nuclear form factor and elastic and inelastic scattering (for large kinetic energy). For a 10 MeV boosted dark matter with boost $\sim$ 10-100, the effect of DM-electron scattering is found to be severe than the DM-nucleus scattering (with form factor) if DM-nucleon scattering cross section is $10^{-29}$cm${}^2$. We also show how the peak position of the boosted dark matter flux shifts due to the attenuation of its kinetic energy.

    hep-phhep-exPRD(2025)·3 citations
11. 11*

    Probing the axion-photon coupling with space-based gravitational waves detectors

    Jordan Gué🇫🇷 · Aurélien Hees🇫🇷 · Peter Wolf🇫🇷

    We propose a simple modification of space-based gravitational wave (GW) detector optical benches which would enable the measurement of vacuum birefringence of light induced by axion dark matterthrough its coupling to electromagnetism. Specifically, we propose to change a half-wave plate by a circular polarizer. While marginally affecting the sensitivity to GW by a factor $\sqrt{2}$, we show that such an adjustment would make future detectors such as LISA, TianQin, Taiji and Big-Bang Observer the most sensitive experiments at low axion masses

    hep-phastro-ph.COgr-qcphysics.opticsClass.Quant.Grav.(2025)·14 citations
12. 12*

    The electromagnetic pion form factor and its phase

    Pablo Sanchez-Puertas🇪🇸 · Enrique Ruiz Arriola🇪🇸

    In this work, we employ a dispersion relation that allows to recover the electromagnetic form factor of the pion from its modulus along the unitarity cut. Unlike the standard dispersive approach, this method extends in a straightforward manner above the inelastic region, allowing us to obtain the form factor's phase, as well as its real and imaginary parts. As applications, we extract the $P$-wave $\pi \pi$ phase shift, the octet form factor, derive bounds in the spacelike region, and offer insights into the onset of perturbative QCD.

    hep-phhep-exhep-latPoS(2025)·5 citations
13. 13*

    Understanding of the BESIII measurement of (anti)hyperon-nucleon scattering

    Xiao-Yun Wang🇨🇳 · Yuan Gao🇨🇳 · Xiang Liu🇨🇳

    Focusing on the recent measurements of the scattering processes $\bar{\Lambda }p\to \bar{\Lambda }p$ and $\Lambda p\to \Lambda p$ reported by BESIII, we offer a dynamical interpretation of the differences in the measured total and differential cross sections for both processes. This discrepancy arises because the $u$-channel contribution is forbidden for $\bar{\Lambda }p\to \bar{\Lambda }p$ but allowed for $\Lambda p\to \Lambda p$. Additionally, we examine the enhancement effect in the forward angle region of the differential cross section for $\bar{\Lambda }p$ elastic scattering, attributed to the $t$-channel contribution. This work serves as a test to the scattering mechanism involved in these reactions.

    hep-phPLB(2025)·8 citations
14. 14*

    Probing Light Scalars and Vector-like Quarks at the High-Luminosity LHC

    Umar Sohail Qureshi🇺🇸 · Andres Flórez🇨🇴 · Alfredo Gurrola🇺🇸 · Cristian Rodriguez🇨🇴

    A model based on a $U(1{)}_{T_R^3}$ extension of the Standard Model can address the mass hierarchy between generations of fermions, explain thermal dark matter abundance, and the muon $g-2$, $R_{(D)}$, and $R_{(D^{\ast })}$ anomalies. The model contains a light scalar boson ${\varphi }^{\prime }$ and a heavy vector-like quark ${\chi }_{\mathrm{u}}$ that can be probed at CERN's Large Hadron Collider (LHC). We perform a phenomenology study on the production of ${\varphi }^{\prime }$ and ${\chi }_u$ particles from proton-proton $(\mathrm{pp})$ collisions at the LHC at $\sqrt{s}=13.6$ TeV, primarily through $g-g$ and $t-{\chi }_{\mathrm{u}}$ fusion. We work under an effective field theory approach, in which the ${\chi }_{\mathrm{u}}$ and ${\varphi }^{\prime }$ masses are free parameters. We perform a phenomenological analysis considering ${\chi }_{\mathrm{u}}$ final states to b-quarks, muons, and neutrinos, and ${\varphi }^{\prime }$ decays to ${\mu }^{+}{\mu }^{-}$. A machine learning algorithm is used to maximize the signal sensitivity, considering an integrated luminosity of $3000$ ${\text{fb}}^{-1}$. The proposed methodology can be a key mode for discovery over a large mass range, including low masses, traditionally considered difficult due to experimental constraints.

    hep-phEPJC(2025)·9 citations
15. 15*

    Vortical effects and the critical end point in the Linear Sigma Model coupled to quark

    Luis A. Hernández🇲🇽 · R. Zamora🇨🇱

    In this paper, we study the effects of vorticity on the QCD phase transition using the Linear Sigma Model coupled to quarks. By going beyond the mean-field approximation and incorporating screening effects via ring diagrams, we explore the chiral symmetry restoration in extreme conditions, such as high temperatures, high densities, and large angular velocities. Our analysis reveals how the critical temperature decreases as the angular velocity increases, suggesting that vorticity catalyzes the symmetry restoration. Additionally, we observe a shift in the Critical End Point (CEP) in the effective QCD phase diagram, where higher angular velocities move the CEP to lower quark chemical potentials and higher temperatures. Moreover, we analyze the baryon number fluctuations through the normalized fourth moment $\kappa {\sigma }^2=c_4/c_2$ as a function of the collision energy in heavy-ion reactions $\sqrt{s_{NN}}$, which serves as a key observable to identify the CEP. Our study reveals that for high collision energies, $\kappa {\sigma }^2$ remains nearly constant; however, as the system approaches the CEP, the ratio increases sharply, indicating the proximity of the critical region. This rise is influenced by the presence of vorticity, which causes the CEP to shift to higher collision energies. These findings provide insight into the role of vorticity in heavy-ion collisions

    hep-phhep-thPRD(2025)·14 citations
16. 16*

    A Bound on Light Dark Photon Dark Matter

    Naoya Kitajima🇯🇵 · Shota Nakagawa🇨🇳 · Fuminobu Takahashi🇯🇵 · Wen Yin🇯🇵

    We derive a bound on dark photon dark matter scenarios where the dark photon mass is generated through the Higgs mechanism, based on the requirement that symmetry breaking must occur sufficiently early in the universe. We emphasize that dark photon production occurs successfully when the dark Higgs field remains in the symmetric phase due to non-thermal trapping effects. For renormalizable Higgs potentials, our bound reads $$\frac{m_{{\gamma }^{\prime }}}{q_H{e}_H}\gg 60\mathrm{eV}{\left(\frac{2\pi }{\lambda }\right)}^{1/4}$$ where $m_{{\gamma }^{\prime }}$ is the dark photon mass, $e_H$ is the gauge coupling, $q_H$ is the charge of the dark Higgs boson, and $\lambda$ is the Higgs quartic coupling}. This constraint holds independently of any complications arising from the Schwinger effect and vortex formation in the Higgsed phase. For more general Higgs potentials such as the Coleman-Weinberg type potential, our bound yields different forms. We argue that late-time symmetry breaking of the dark U(1) symmetry satisfying our bound has only a mild impact on both the abundance and momentum distribution of dark photon dark matter, and therefore does not pose any serious problem for the dark photon dark matter scenario.

    hep-phastro-ph.COhep-exPLB(2025)·10 citations
17. 17*

    Novel approach to investigate ATOMKI anomaly using Coherent CAPTAIN-Mills detectors

    Bhaskar Dutta🇺🇸 · Bai-Shan Hu🇺🇸 · Wei-Chih Huang🇺🇸 · Richard G. Van de Water🇺🇸

    ATOMKI nuclear anomaly has suggested a new BSM (Beyond the Standard Model) boson with mass $\sim 17$ MeV emitted from excited nuclei and quickly decays into a pair of $e^{+}{e}^{-}$. In order to search for the new particle, we propose a new approach that utilizes the ongoing Coherent CAPTAIN-Mills (CCM) 10-ton LAr (liquid argon) detectors. The neutrons from the Lujan target can scatter inelastically by the PMT glass in the CCM detector can produce the new boson which solves the ATOMKI anomaly. The new boson can be detected from its decay to a $e^{+}{e}^{-}$ pair. We find that CCM probes a large area of the anomaly-allowable parameter space. We also show the prediction for a 100-ton LAr detector and 5-ton EOS water detector.

    hep-phnucl-thPRL(2025)·7 citations
18. 18*

    Semileptonic $B\to D^{\ast }$ decays from light to $\tau$ leptons: the extraction of the form factor $F_2$ from data

    G. Martinelli🇮🇹 · S. Simula🇮🇹 · L. Vittorio🇫🇷

    We extend the Standard Model (SM) analysis of Ref. [1], which was limited to light leptons in the final state, to the semileptonic $B\to D^{\ast }\tau {\nu }_{\tau }$ decay. By using quantities that can be analised without the knowledge of $|V_{cb}|$, we derive important information about the helicity amplitudes and the hadronic form factors that can be compared with the predictions of lattice QCD calculations. In particular, there is a difficulty in reproducing simultaneously the experimental values of $R(D^{\ast })$ and of other quantities relevant for the semitauonic decays within the SM. As a byproduct of our analysis, we also present a determination of $|V_{cb}|$ from the total decay rate.

    hep-phhep-exhep-latEPJC(2025)·10 citations
19. 19*

    An improved Bell-CHSH observable for gauge boson pairs

    Radosław Grabarczyk🇬🇧

    For particles decaying without parity violation, it is impossible to reconstruct the full spin-density matrix from the velocities of their decay products. In this work, we consider Bell inequalities based on squares of spin operators. The corresponding Bell operators probe only the part of the density matrix that can be reconstructed from any gauge boson decay or splitting to fermions, which is accessible regardless of whether parity is violated. We find that our new choice of Bell operator has promising properties regarding states seen at colliders. In particular, it substantially outperforms the inequality previously used for the $pp\to ZZ$ process at the LHC in terms of the phase space volume in which it is violated. We also conduct the first investigation of Bell violation in a system involving gauge bosons mediating different interactions, namely the $W$ boson and gluon in the $pp\to W^{\pm }(g\to b\bar{b})$ process.

    hep-phhep-exquant-ph17 citations
20. 20*

    Scaling density of axion strings in terasite simulations

    José Correia🇫🇮 · Mark Hindmarsh🇫🇮 · Joanes Lizarraga🇪🇸 · Asier Lopez-Eiguren🇪🇸 · Kari Rummukainen🇫🇮 · Jon Urrestilla🇪🇸

    We report on a study of axion string networks using fixed-grid simulations of up to $16384$ points per side. The length of string can be characterised in terms of standard dimensionless parameters ${\zeta }_{\text{w}}$ and ${\zeta }_{\text{r}}$, the length density measured in the cosmic rest frame and the string rest frame, scaled with the cosmic time. The motion of the string can be characterised by the root-mean-square (RMS) velocity of the string. Starting from a range of initial length densities and velocities, we analyse the string network in the standard scaling framework and find evolution towards a fixed point with estimated values ${\hat{\zeta }}_{\text{w},\ast }=1.220(57)$ and ${\hat{\zeta }}_{\text{r},\ast }=1.491(93)$. The two measures are related by the RMS velocity, which we estimate to be ${\hat{v}}_{\ast }=0.5705(93)$. The length density is consistent with previous measurements, while the velocity is about 5% lower. For simulations starting from low enough density, the length density parameters ${\zeta }_{\text{w}}$ and ${\zeta }_{\text{r}}$ remain below their fixed point values throughout, while growing slowly, giving rise to an impression of approximately logarithmic increase with time. This has been proposed as the true long-term behaviour. We find that the growth tends to slow down as the values of ${\zeta }_{\text{w}}$ and ${\zeta }_{\text{r}}$ identified as fixed points are approached. In the case of ${\zeta }_{\text{r}}$, the growth stops for simulations which started close to the fixed point length density. The difference between ${\zeta }_{\text{w}}$ and ${\zeta }_{\text{r}}$ can be understood to result from the continuing velocity evolution. Our results indicate that the growth of ${\zeta }_{\text{w}}$ is a transient appearing at low densities and while the velocity is converging. This highlights the importance of studying the string density and the velocity together, and the preparation of initial conditions.

    hep-phPRD(2025)·28 citations
21. 21*

    Regulating Sommerfeld resonances for multi-state systems and higher partial waves

    Aditya Parikh🇺🇸 · Ryosuke Sato🇯🇵 · Tracy R. Slatyer🇺🇸

    Long-range attractive interactions between dark matter particles can significantly enhance their annihilation, particularly at low velocities. This ``Sommerfeld enhancement'' is typically computed by evaluating the deformation of the two-particle wavefunction due to the long-range potential, while ignoring the physics associated with the annihilation, and then scaling the appropriate annihilation matrix elements by factors that depend on the wavefunction in the limit where the particles approach zero relative separation. It has long been recognized that this approach is a valid approximation only in the limit where the annihilation rate is small, and breaks down in the regime where the enhanced annihilation rate approaches the unitarity bound, in which case ignoring the impact of the annihilation physics on the two-particle wavefunction cannot be justified and leads to apparent violations of unitarity. In the case where the physics relevant to annihilation occurs at a parametrically shorter distance scale (higher energy scale) compared with the long-range potential, we provide a simple prescription for correcting the Sommerfeld enhancement for the effects of the short-range physics, valid for all partial waves and for systems where multiple states are coupled by the long-range potential.

    hep-phastro-ph.COastro-ph.GAhep-thJHEP(2025)·9 citations
22. 22*

    Angular integrals with three denominators via IBP, mass reduction, dimensional shift, and differential equations

    Juliane Haug🇩🇪 · Fabian Wunder🇩🇪

    Angular integrals arise in a wide range of perturbative quantum field theory calculations. In this work we investigate angular integrals with three denominators in $d=4-2\epsilon$ dimensions. We derive integration-by-parts relations for this class of integrals, leading to explicit recursion relations and a reduction to a small set of master integrals. Using a differential equation approach we establish results up to order $\epsilon$ for general integer exponents and masses. Here, reduction identities for the number of masses, known results for two-denominator integrals, and a general dimensional-shift identity for angular integrals considerably reduce the required amount of work. For the first time we find for angular integrals a term contributing proportional to a Euclidean Gram determinant in the $\epsilon$-expansion. This coefficient is expressed as a sum of Clausen functions with intriguing connections to Euclidean, spherical, and hyperbolic geometry. The results of this manuscript are applicable to phase-space calculations with multiple observed final-state particles.

    hep-phhep-thJHEP(2025)·6 citations
23. 23*

    Precise predictions for the QCD axion contribution to dark radiation with full phase-space evolution

    Marcin Badziak🇵🇱 · Maxim Laletin🇵🇱

    We compute the QCD axion contribution to the energy density of dark radiation, parameterized by $\Delta N_{\mathrm{eff}}$, by solving Boltzmann equations for the momentum distribution functions including the effects of quantum statistics for all particles involved in the axion production processes. This approach gives precise prediction for $\Delta N_{\mathrm{eff}}$ independently on whether axions are produced via freeze-out or freeze-in. We focus on axions produced via flavor-conserving and flavor-violating interactions with leptons. Our precise predictions for $\Delta N_{\mathrm{eff}}$ can differ from those assuming thermal shape for the momentum distribution functions, as commonly done in the literature, by more than the experimental precision of future Cosmic Microwave Background (CMB) observations. Current lower limits on the axion couplings from Planck constraints on $\Delta N_{\mathrm{eff}}$ are also affected by our precise computation which, in particular, results in a strongly relaxed bound on flavor-violating axion couplings to tau lepton and muon or electron.

    hep-phastro-ph.COJHEP(2025)·22 citations
24. 24*

    Total cross section of the process $e^{+}+e^{-}\to {\Sigma }^{+}+{\bar{\Sigma }}^{-}$ including the $D$-meson loop and three-gluon contributions

    Azad I. Ahmadov🇦🇿

    In the present paper, we investigate the production of a baryon pair in $e^{+}{e}^{-}$ annihilation to study the structure of baryons. To study the basic structure of the Standard Model, it is also necessary to consider the baryon-antibaryon pair production at the electron-positron linear collider. The production of a baryon pair in electron-positron annihilation provides a powerful tool at higher center-of-mass energies. In this work, we present phenomenological results for ${\Sigma }^{+}{\bar{\Sigma }}^{-}$ production in $e^{+}{e}^{-}$ collision at the BESIII Collider. We investigate a hyperon pair produced in the reaction $e^{+}{e}^{-}\to {\Sigma }^{+}{\bar{\Sigma }}^{-}$. Two different contributions are considered: the $D$ meson loop and the three-gluon charmonium annihilation loop. Taking into account the contributions of the $D$-meson loop and three-gluon loops and the interference of all diagrams, we calculate the total cross section of the process $e^{+}{e}^{-}\to {\Sigma }^{+}{\bar{\Sigma }}^{-}$. With respect to a purely electromagnetic mechanism, large relative phases are generated for these contributions. We obtain as a byproduct a fit of the electromagnetic form factor of the $\Sigma$ hyperon for a large momentum transferred region. In this process, in addition to $\psi (3770)$ charmonium, we also take into account the contributions of other charmonium (-like) states, $\psi (4040)$, \,\,$\psi (4160)$, \,\,$Y(4230)$,\,\,$Y(4360)$,\,\,$\psi (4415)$, and $Y(4660)$. The obtained results are in good agreement with experimental data.

    hep-phPRD(2025)·1 citation
25. 25*

    Gravitational waves from burdened primordial black holes dark matter

    Ngo Phuc Duc Loc🇺🇸

    Primordial black holes (PBHs) are the natural candidate of dark matter (DM) as they only interact gravitationally and can evade any experiments on earth. In the standard semiclassical calculation of Hawking radiation, PBHs with mass below $10^{15}\mathrm{g}$ evaporated by now and therefore cannot be DM. However, the recently-discovered quantum memory burden effect can significantly suppress the evaporation of PBHs after the half-decay time. This quantum effect could open up a new mass window below $10^{10}\mathrm{g}$ where PBHs can still exist today and be DM. In this paper, we compute the gravitational wave (GW) signals associated with the formation of PBHs in this new mass window. We consider two formation scenarios: PBHs formed from inflationary perturbation and PBHs formed from collapse of Fermi-balls in a first-order phase transition (FOPT). GWs produced from these two scenarios have distinct features and, while the GW from inflation peaks at high frequency, the GW from FOPT peaks at lower frequency that can be within the reach of future experiments.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2025)·27 citations
26. 26*

    QCD Lambda Parameter from Gradient Flow

    Gerrit Schierholz🇩🇪

    Starting from the running coupling in the gradient flow scheme, the QCD Lambda parameter ${\Lambda }_{\overline{\mathrm{MS}}}$ is determined analytically with respect to the reference scale $w_0$ in the pure gauge theory. A key element is the gluon condensate, which, being invariant under RG transformations, establishes a formal relationship between ${\Lambda }_{\overline{\mathrm{MS}}}$ and $w_0$. Good agreement with numerical estimates is found.

    ↳ hep-lathep-phEPJC(2025)·6 citations
27. 27*

    Fermion Masses and Mixing in String-Inspired Models

    Andrei Constantin🇬🇧 · Kit Fraser-Taliente🇬🇧 · Thomas R. Harvey🇺🇸 · Lucas T. Y. Leung🇬🇧 · Andre Lukas🇬🇧

    We study a class of supersymmetric Froggatt-Nielsen (FN) models with multiple U(1) symmetries and Standard Model (SM) singlets inspired by heterotic string compactifications on Calabi-Yau threefolds. The string-theoretic origin imposes a particular charge pattern on the SM fields and FN singlets, dividing the latter into perturbative and non-perturbative types. Employing systematic and heuristic search strategies, such as genetic algorithms, we identify charge assignments and singlet VEVs that replicate the observed mass and mixing hierarchies in the quark sector, and subsequently refine the Yukawa matrix coefficients to accurately match the observed values for the Higgs VEV, the quark and charged lepton masses and the CKM matrix. This bottom-up approach complements top-down string constructions and our results demonstrate that string FN models possess a sufficiently rich structure to account for flavour physics. On the other hand, the limited number of distinct viable charge patterns identified here indicates that flavour physics imposes tight constraints on string theory models, adding new constraints on particle spectra that are essential for achieving a realistic phenomenology.

    ↳ hep-thhep-phJHEP(2025)·9 citations
28. 28*

    Finite-volume effects in the $\delta$-regime

    Ulf-G. Meißner (Bonn U., HISKP and FZ Jülich, IAS and Tbilisi State U.)🇩🇪 · Fabian Müller (Bonn U., HISKP)🇩🇪 · Akaki Rusetsky (Bonn U., HISKP and Tbilisi State U.)🇩🇪

    We derive a systematic perturbative expansion for the finite-volume energy spectrum of the non-linear $O(N)$ $\sigma$-model in the $\delta$-regime. The violation of the power-counting rules that emerges after the separation of the fast and slow modes is dealt with to all orders by use of the threshold expansion. The known result for the rest-frame energy spectrum up-to-and-including next-to-next-to-leading order is reproduced.

    ↳ hep-latcond-mat.stat-mechhep-phhep-thJHEP(2025)·0 citations
29. 29*

    Cosmology of Quasi-Dilaton Massive Gravity with Non-minimal Kinetic Coupling

    Sobhan Kazempour🇨🇳 · Amin Rezaei Akbarieh🇮🇷 · Sichun Sun🇨🇳 · Chengye Yu🇨🇳

    In this study, we introduce an extension of the quasi-dilaton massive gravity theory and derive the field equations by varying the action with respect to the metric. This extension elucidates the dynamics of the system and demonstrates how it can encompass and recover previous cosmological models through different parameter values. We present the cosmological background equations to analyze self-accelerating solutions that can explain the late-time accelerated expansion of the Universe, driven by an effective cosmological constant arising from massive gravity. Besides, we apply the quasi-dilaton massive gravity theory with non-minimal kinetic coupling to a Type Ia Supernovae (SNIa) data set to test its viability. Our findings indicate that the theory is able to account for the observed acceleration of the expansion of the universe without invoking dark energy. In addition, we carry out a comprehensive perturbation analysis examining tensor, vector, and scalar perturbations independently. We derive the dispersion relation of gravitational waves in a Friedman-Lemaitre-Robertson-Walker (FLRW) cosmology and determine the stability conditions of the system. Such an analysis results in a sharper quasi-dilaton massive gravity theory with non-minimal kinetic coupling by ensuring the stability conditions of the system are maintained and that strong constraints on theory parameters are provided.

    ↳ gr-qcastro-ph.COhep-phNPB(2025)·1 citation
30. 30*

    Finite Integrals from Feynman Polytopes

    Leonardo de la Cruz🇫🇷 · David A. Kosower🇫🇷 · Pavel P. Novichkov🇫🇷

    We investigate a geometric approach to determining the complete set of numerators giving rise to finite Feynman integrals. Our approach proceeds graph by graph, and makes use of the Newton polytope associated to the integral's Symanzik polynomials. It relies on a theorem by Berkesch, Forsgård, and Passare on the convergence of Euler--Mellin integrals, which include Feynman integrals. We conjecture that a necessary in addition to a sufficient condition is that all parameter-space monomials lie in the interior of the polytope. We present an algorithm for finding all finite numerators based on this conjecture. In a variety of examples, we find agreement between the results obtained using the geometric approach, and a Landau-analysis approach developed by Gambuti, Tancredi, and two of the authors.

    ↳ hep-thhep-phPRD(2025)·14 citations
31. 31*

    Relativistic fluid dynamics in a 'hydro' frame

    Sayantani Bhattacharyya🇬🇧 · Sukanya Mitra🇮🇳 · Shuvayu Roy🇮🇳 · Rajeev Singh🇷🇴

    In this letter, we investigate how field redefinition influences the spectrum of linearized perturbations in relativistic fluid dynamics. We show that the hydrodynamic modes do not get affected under local field redefinition, whereas the non-hydrodynamic modes do. These non-hydrodynamic modes can be removed through a suitable all-order field redefinition. This process leads to a new frame containing only hydrodynamic modes, which we refer to as the hydro frame. Additionally, we demonstrate that the resulting stress-energy tensor may constitute an infinite series in momentum space, with the radius of convergence associated with the removed non-hydrodynamic mode, highlighting its role in the hydrodynamic expansion's validity.

    ↳ nucl-thgr-qchep-phhep-th5 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.