Wed·Apr 10, 2024Wednesday·April 10, 2024

1. 01*

   Vector meson production using the Balitsky-Kovchegov equation including the dipole orientation

   Jan Cepila🇨🇿 · Jesus Guillermo Contreras🇨🇿 · Matej Vaculciak🇨🇿

   In this proceedings a solution of the target-rapidity Balitsky-Kovchegov (BK) equation is presented considering the complete impact-parameter dependence, including the orientation of the dipole with respect to the impact-parameter vector. The target-rapidity formulation of the BK equation introduces non-locality in rapidity. Three different prescriptions are considered to take into account the rapidities preceding the initial condition. The solutions are used to compute the structure functions of the proton and the diffractive photo- and electro-production of J/{\psi} off protons. The predictions agree well with HERA data, confirming that the target-rapidity Balitsky-Kovchegov equation with the full impact-parameter dependence is a viable tool to study the small Bjorken-x limit of perturbative QCD at current facilities like RHIC and LHC as well as in future colliders like the EIC.

   hep-phPhys.Proc.UPC(2024)·0 citations
2. 02*

   The $SU(3{)}_C\times SU(3{)}_L\times U(1{)}_X$ (331) Model:Addressing the Fermion Families Problem within Horizontal Anomalies Cancellation

   Claudio Corianò🇮🇹 · Dario Melle🇮🇹

   One of the most important and unanswered problems in particle physics is the origin of the three generations of quarks and leptons. The standard Model does not provide any hint regarding its sequential charge assignments, which remain a fundamental mystery of Nature. One possible solution of the puzzle is to look for charge assignments, in a given gauge theory, that are inter-generational, by employing the cancellation of the gravitational and gauge anomalies horizontally. The 331 model, based on an $SU(3{)}_C\times SU(3{)}_L\times U(1{)}_X$ does it in an economic way, and defines a possible extension of the Standard Model, where the number of families has to be necessarily three. We review the model in Frampton's formulation, that predicts the existence of bileptons. Another characteristics of the model is to unify the $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_X$ into the 331 symmetry at a scale which is in the TeV range, and can be tested at the LHC. Expressions of the scalar mass eigenstates and of the renormalization group equations of the model are also presented.

   hep-phEntropy(2024)·4 citations
3. 03*

   Entanglement suppression and low-energy scattering of heavy mesons

   Tao-Ran Hu🇨🇳 · Su Chen🇨🇳 · Feng-Kun Guo🇨🇳

   Recently entanglement suppression was proposed to be one possible origin of emergent symmetries. Here we test this conjecture in the context of heavy meson scatterings. The low-energy interactions of $D^{(\ast )}{\bar{D}}^{(\ast )}$ and $D^{(\ast )}{D}^{(\ast )}$ are closely related to the hadronic molecular candidates $X(3872)$ and $T_{cc}(3875{)}^{+}$, respectively, and can be described by a nonrelativistic effective Lagrangian manifesting heavy-quark spin symmetry, which includes only constant contact potentials at leading order. We explore entanglement suppression in a tensor-product framework to treat both the isospin and spin degrees of freedom. Using the $X(3872)$ and $T_{cc}(3875{)}^{+}$ as inputs, we find that entanglement suppression indeed leads to an emergent symmetry, namely, a light-quark spin symmetry, and as such the $D^{(\ast )}{\bar{D}}^{(\ast )}$ or $D^{(\ast )}{D}^{(\ast )}$ interaction strengths for a given total isospin do not depend on the total angular momentum of light (anti)quarks. The $X(3872)$ and $T_{cc}(3875{)}^{+}$ are predicted to have five and one isoscalar partner, respectively, while the corresponding partner numbers derived solely from heavy-quark spin symmetry are three and one, respectively. The predictions need to be confronted with experimental data and lattice quantum chromodynamics results to further test the entanglement suppression conjecture.

   hep-phhep-exhep-thnucl-th+1PRD(2024)·23 citations
4. 04*

   Explaining the cosmological dark matter coincidence in asymmetric dark QCD

   Alexander C. Ritter🇦🇺 · Raymond R. Volkas🇦🇺

   To properly solve the coincidence problem (${\Omega }_{\mathrm{DM}}\simeq 5{\Omega }_{\mathrm{VM}}$) in a model of asymmetric dark matter, one cannot simply relate the number densities of visible and dark matter without also relating their particle masses. Following previous work, we consider a framework where the dark matter is a confined state of a dark QCD gauge group whose confinement scale is dynamically related to the QCD confinement scale by a mechanism utilising infrared fixed points of the two gauge couplings. In this work we present a new, `zero-coupling infrared fixed point' approach, which allows a larger proportion of models in this framework to generically relate the masses of the visible and dark matter particles. Due to the heavy mass scale required for the new field content, we introduce supersymmetry to the theory. We consider how these models may be incorporated in a full theory of asymmetric dark matter, presenting some example leptogenesis-like models. We also discuss the phenomenology of these models; in particular, there are gravitational wave signals which, while weak, may be measurable at future mHz and $\mu$Hz detectors.

   hep-phPRD(2024)·19 citations
5. 05*

   Inflation, Proton Decay and Gravitational Waves from Metastable Strings in $SU(4{)}_C\times SU(2{)}_L\times U(1{)}_R$ Model

   Waqas Ahmed🇨🇳 · Maria Mehmood🇵🇰 · Mansoor Ur Rehman🇵🇰 · Umer Zubair🇺🇸

   We present a realistic supersymmetric $\mu$-hybrid inflation model within the framework of $SU(4{)}_C\times SU(2{)}_L\times U(1{)}_R$ gauge symmetry, wherein the symmetry breaking $SU(4{)}_C\times SU(2{)}_L\times U(1{)}_R\to SU(3{)}_C\times SU(2{)}_L\times U(1{)}_{B-L}\times U(1{)}_R$ occurs before observable inflation, effectively eliminating topologically stable primordial monopoles. Subsequent breaking of $U(1{)}_{B-L}\times U(1{)}_R\to U(1{)}_Y$ after inflation leads to the formation of superheavy metastable cosmic strings (CSs), capable of producing a stochastic gravitational wave background (SGWB) consistent with the recent PTA data. Moreover, the scalar spectral index $n_s$ and the tensor-to-scalar ratio $r$ align with Planck 2018 observations. A consistent scenario for reheating and non-thermal leptogenesis is employed to explain the observed matter content of the universe. Finally, the embedding of $G_{421}$ into the Pati-Salam gauge symmetry $G_{422}$ is briefly discussed, predicting potentially observable proton decay rates detectable at facilities such as Hyper Kamiokande and DUNE.

   hep-phgr-qcJCAP(2025)·12 citations
6. 06*

   Higgs Alignment from Multicritical-Point Principle in Two Higgs Doublet Models

   Hikaru Kawai🇹🇼 · Kiyoharu Kawana🇰🇷 · Kin-ya Oda🇯🇵 · Kei Yagyu🇯🇵

   In models with non-minimal Higgs sectors, enforcing (near) Higgs alignment, necessary to prevent significant deviations in the Higgs boson coupling from the standard model prediction, causes a serious fine-tuning problem. We demonstrate that the Higgs alignment is naturally deduced from the multicritical point principle (MPP) in the general two Higgs doublet model. Furthermore, we discuss the possibility of realizing the Yukawa alignment from the MPP, which is necessary to prevent flavor-changing neutral currents mediated by Higgs bosons at tree level.

   hep-phhep-thEPJC(2025)·0 citations
7. 07*

   Thermal axion production at hard and soft momenta

   Killian Bouzoud🇫🇷 · Jacopo Ghiglieri🇫🇷

   Hot axions, thermally produced in the Early Universe, would contribute to dark radiation and are thus subject to present and future constraints from $N_{\mathrm{eff}}$. In this paper we quantify the contribution to $N_{\mathrm{eff}}$ and its uncertainty in models with axion-gluon couplings from thermal dynamics above the QCD transition. In more detail, we determine the leading-order thermal axion production rate for axion momenta of the order of the temperature adopting three different schemes for the incorporation of the collective dynamics of soft gluons. We show how these three schemes extrapolate differently into the regime of softer axion production, thus giving us a first quantitative handle on the theory uncertainty of the rate. Upon solving the Boltzmann equation, we find that this theory uncertainty translates to an uncertainty of order 0.002 for the contribution to $N_{\mathrm{eff}}$ prior to the QCD crossover. The uncertainty from common momentum-averaged approximations to the Boltzmann equation is smaller. We also discuss how QCD transition dynamics would need to be integrated into our results and we show how existing rate determinations in the literature based on gauge-dependent resummations are problematic.

   hep-phastro-ph.COJHEP(2025)·29 citations
8. 08*

   Soft contributions to the thermal Higgs width across an electroweak phase transition

   M. Eriksson🇨🇭 · M. Laine🇨🇭

   We estimate the equilibration rate of a nearly homogeneous Higgs field, displaced from its ground state during the onset of an electroweak phase transition. The computation is carried out with Hard Thermal Loop resummed perturbation theory, and a significant part of the result originates from Bose-enhanced $t$-channel $2\leftrightarrow 2$ scatterings. The expression is shown to be IR finite and gauge independent. Possible applications to Langevin simulations of bubble nucleation are mentioned, and we also contrast with the friction affecting bubble growth.

   hep-phJCAP(2024)·4 citations
9. 09*

   Aspects of confinement within non-Abelian gauge theories

   Urko Reinosa🇫🇷

   These lectures cover two aspects: first, irrespectively of the particular approach followed to tackle the QCD phase diagram, we introduce some tools that help discussing the confinement/deconfinement transition in the continuum; second, within one particular continuum approach, based on the Curci-Ferrari model, we illustrate the use of these various notions in order the describe to the confinement/deconfinement transition.

   hep-phhep-thEPJC(2025)·6 citations
10. 10*

    Quark flavor violation and axion-like particles from top-quark decays at the LHC

    Kingman Cheung🇹🇼 · Fei-Tung Chung🇹🇼 · Giovanna Cottin🇨🇱 · Zeren Simon Wang🇹🇼

    We study axion-like particles (ALPs) with quark-flavor-violating couplings at the LHC. Specifically, we focus on the theoretical scenario with ALP-top-up and ALP-top-charm interactions, in addition to the more common quark-flavor-diagonal couplings. The ALPs can thus originate from decays of top quarks which are pair produced in large numbers at the LHC, and then decay to jets. If these couplings to the quarks are tiny and the ALPs have $\mathcal{O}(10)$ GeV masses, they are long-lived, leading to signatures of displaced vertex plus multiple jets, which have the advantage of suppression of background events at the LHC. We recast a recent ATLAS search for the same signature and reinterpret the results in terms of bounds on the long-lived ALP in our theoretical scenario. We find that the LHC with the full Run 2 dataset can place stringent limits, while at the future high-luminosity LHC with 3 ab${}^{-1}$ integrated luminosity stronger sensitivities are expected.

    hep-phhep-exJHEP(2024)·22 citations
11. 11*

    Production of $D^{(\ast )}{\bar{D}}^{(\ast )}$ near the thresholds in $e^{+}{e}^{-}$ annihilation

    S.G. Salnikov🇷🇺 · A.I. Milstein🇷🇺

    It is shown that the nontrivial energy dependencies of $D\bar{D}$, $D{\bar{D}}^{\ast }$, and $D^{\ast }{\bar{D}}^{\ast }$ pair production cross sections in $e^{+}{e}^{-}$ annihilation are well described within the approach based on account for the final-state interaction of produced particles. This statement is valid for production of charged and neutral particles. Interaction of $D^{(\ast )}$ and ${\bar{D}}^{(\ast )}$ is taken into account using the effective potential method. Its applicability is based on the fact that for near-threshold resonance the characteristic width of peak in the wave function is much larger than the interaction radius. The transition amplitudes between all three channels play an important role in the description of cross sections. These transitions are possible since all channels have the same quantum numbers $J^{PC}=1^{--}$.

    hep-phhep-exPRD(2024)·12 citations
12. 12*

    Study of the timelike electromagnetic form factors of the ${\Lambda }_c$

    Di Guo🇨🇳 · Qin-He Yang🇨🇳 · Ling-Yun Dai🇨🇳

    In this paper, the reaction of electron-positron annihilation into ${\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ is investigated. The ${\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ scattering amplitudes are obtained by solving the Lippmann-Schwinger equation. The contact, annihilation, and two pseudoscalar-exchange potentials are taken into account in the spirit of the chiral effective field theory. The amplitudes of $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ are constructed by the distorted wave Born approximation method, with the final state interactions of the ${\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ re-scattering implemented. By fitting to the experimental data, the unknown couplings are fixed, and high-quality solutions are obtained. With these amplitudes, the individual electromagnetic form factors in the timelike region, $G_E^{{\Lambda }_c}$, $G_M^{{\Lambda }_c}$, and their ratio, $G_E^{{\Lambda }_c}/G_M^{{\Lambda }_c}$, are extracted. Both modulus and phases are predicted. These individual electromagnetic form factors reveal new insights into the properties of the ${\Lambda }_c$. The separated contributions of the Born term, contact, annihilation, as well as the two pseudoscalar exchange potentials to the electromagnetic form factors are isolated. It is found that the Born term dominates the whole energy region. The contact term plays a crucial role in the enhancement near the threshold, and the annihilation term is essential in generating the fluctuation of the electromagnetic form factors.

    hep-phnucl-thPRD(2024)·6 citations
13. 13*

    Polarization and quantum entanglement effects in $B_c^{\pm }\to J/\psi +{\pi }^{\pm }+{\pi }^0$ process

    Kaiwen Chen🇨🇳 · Yiqi Geng🇨🇳 · Yichao Jin🇨🇳 · Zhicheng Yan🇨🇳 · Ruilin Zhu🇨🇳

    Motivated by the very recent observation of the $B_c^{+}\to J/\psi +{\pi }^{+}+{\pi }^0$ decay using proton-proton collision data by the LHCb collaboration, we study the four-body angular distributions and the quantum entanglement effects in the $B_c^{+}\to J/\psi +{\pi }^{+}+{\pi }^0$ associated with $J/\psi \to {\mu }^{+}+{\mu }^{-}$. The helicity angular distributions are given in the QCD effective theory and the von Neumann entropy is obtained in $B_c^{\pm }\to J/\psi (\to {\mu }^{+}{\mu }^{-})+{\rho }^{\pm }(\to {\pi }^{\pm }{\pi }^0)$ decay process.

    hep-phhep-exEPJC(2024)·5 citations
14. 14*

    Dark sterile neutrinos on a linear seesaw of neutrino masses

    Ernesto A. Matute🇨🇱

    Sterile neutrinos as source of mass and flavor mixing of active neutrinos as well as genesis of dark matter (DM) and matter-antimatter asymmetry have gained special interest. Here we study the case of the Standard Model (SM) extended with three right-handed (RH) neutrinos and a dark sector with two extra sterile neutrinos, odd under a discrete $Z_2$ symmetry. The RH neutrinos are responsible for producing baryon asymmetry via high-scale unflavored leptogenesis. They are superheavy and their abundance at the electroweak broken stage is vanishingly small, so that they have no impact on phenomenology at low energies. The two dark neutrinos generate the tiny mass of two active neutrinos through a mechanism similar to the minimal linear seesaw, and saturate the relic abundance as freeze-in DM coming mainly from decays of SM weak-gauge bosons via active-dark neutrino mixing. The absence of the dark Majorana mass terms in the dark linear seesaw is explained by invoking a hidden symmetry, the so-called presymmetry, and the DM candidate appears in the form of a quasi-Dirac neutrino. The $Z_2$ symmetry is broken in the dark neutrino sector, but exact in the realm of RH neutrinos. The required coupling weakness for the freeze-in DM neutrino is related to a very small breach of the unitarity of the active neutrino mixing matrix. We show how phenomenological constraints on the production and decay of the DM neutrino imply an upper bound around 1 MeV for its mass and unitarity up to $\mathcal{O}(10^{-7})$ for the mixing matrix.

    hep-ph0 citations
15. 15*

    Stress out of charmonia

    Siqi Xu🇨🇳 · Xianghui Cao🇨🇳 · Tianyang Hu🇨🇳 · Yang Li🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

    We investigate the gravitational form factors of charmonium. Our method is based on a Hamiltonian formalism on the light front known as basis light-front quantization. The charmonium mass spectrum and light-front wave functions were obtained from diagonalizing an effective Hamiltonian that incorporates confinement from holographic QCD and one-gluon exchange interaction from light-front QCD. We proposed a quantum many-body approach to construct the hadronic matrix elements of the energy momentum tensor $T^{++}$ and $T^{+-}$, which are used to extract the gravitational form factors $A(Q^2)$ and $D(Q^2)$. The obtained form factors satisfy the known constraints, e.g. von Laue condition. From these quantities, we also extract the energy, pressure and light-front energy distributions of the system. We find that hadrons are multi-layer systems.

    hep-phnucl-thPRD(2024)·12 citations
16. 16*

    Quantum Simulating Nature's Fundamental Fields

    Christian W. Bauer🇺🇸 · Zohreh Davoudi🇺🇸 · Natalie Klco🇺🇸 · Martin J. Savage🇺🇸

    Simulating key static and dynamic properties of matter -- from creation in the Big Bang to evolution into sub-atomic and astrophysical environments -- arising from the underlying fundamental quantum fields of the Standard Model and their effective descriptions, lies beyond the capabilities of classical computation alone. Advances in quantum technologies have improved control over quantum entanglement and coherence to the point where robust simulations are anticipated to be possible in the foreseeable future. We discuss the emerging area of quantum simulations of Standard-Model physics, challenges that lie ahead, and opportunities for progress in the context of nuclear and high-energy physics.

    hep-phnucl-thquant-phNature Rev.Phys.(2023)·226 citations
17. 17*

    Description of the processes $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^0$ and $e^{+}{e}^{-}\to K^{+}{K}^{-}\eta$ within the extended NJL model

    M.K. Volkov🇷🇺 · A.A. Pivovarov🇷🇺 · K. Nurlan🇷🇺

    In the framework of the $U(3)\times U(3)$ extended Nambu-Jona-Lasinio model, the processes $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^0$ and $e^{+}{e}^{-}\to K^{+}{K}^{-}\eta$ are described taking into account both ground and first radially excited intermediate meson states. It is shown that channels with radially excited $\varphi (1680)$ meson are dominant in both processes. The influence on the results of the appearance of phase factors of radially excited intermediate states, the existence of which is indicated by experimental data, is discussed.

    hep-phPhys.Part.Nucl.Lett.(2025)·1 citation
18. 18*

    Causal third-order viscous hydrodynamics within relaxation-time approximation

    Pushpa Panday🇮🇳 · Amaresh Jaiswal🇮🇳 · Binoy Krishna Patra🇮🇳

    In the present work, we derive a linearly stable and causal theory of relativistic third-order viscous hydrodynamics from the Boltzmann equation with relaxation-time approximation. We employ viscous correction to the distribution function obtained using a Chapman-Enskog like iterative solution of the Boltzmann equation. Our derivation highlights the necessity of incorporating a new dynamical degree of freedom, specifically an irreducible tensors of rank three, within this framework. This differs from the recent formulation of causal third-order theory from the method of moments which requires two dynamical degrees of freedom: an irreducible third-rank and a fourth-rank tensor. We verify the linear stability and causality of the proposed formulation by examining perturbations around a global equilibrium state.

    hep-phPRD(2024)·8 citations
19. 19*

    New Contributions to $b\to s\gamma$ in Minimal G2HDM

    Che Hao Liu🇨🇳 · Van Que Tran🇨🇳 · Qiaoyi Wen🇨🇳 · Fanrong Xu🇨🇳 · Tzu-Chiang Yuan🇹🇼

    We study the flavor-changing bottom quark radiative decay $b\to s\gamma$ induced at one-loop level within the minimal gauged two-Higgs-doublet model (G2HDM). Among the three new contributions to this rare process in G2HDM, we find that only the charged Higgs ${\mathcal{H}}^{\pm }$ contribution can be constrained by the current global fit data in $B$-physics. Other two contributions from the complex vectorial dark matter $\mathcal{W}$ and dark Higgs $\mathcal{D}$ are not sensitive to the current data. Combining with theoretical constraints imposed on the scalar potential and electroweak precision data for the oblique parameters, we exclude mass regions $m_{{\mathcal{H}}^{\pm }}\lesssim 250$ GeV and $m_{\mathcal{D}}\lesssim 100$ GeV at the 95\% confidence level.

    hep-phCPC(2025)·4 citations
20. 20*

    Three ways to decipher the nature of exotic hadrons: multiplets, three-body hadronic molecules, and correlation functions

    Ming-Zhu Liu🇨🇳 · Ya-Wen Pan🇨🇳 · Zhi-Wei Liu🇨🇳 · Tian-Wei Wu🇨🇳 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳

    In the past two decades, a plethora of hadronic states beyond the conventional quark model of $q\bar{q}$ mesons and $qqq$ baryons have been observed experimentally, which motivated extensive studies to understand their nature and the non-perturbative strong interaction. Since most of these exotic states are near the mass thresholds of a pair of conventional hadrons, the prevailing picture is that they are primarily hadronic molecules. In principle, one can verify the molecular nature of these states by thoroughly comparing their masses, decay widths, and production rates in a particular picture with experimental data. However, this is difficult or impossible. First, quantum mechanics allows for the mixing of configurations allowed by symmetries and quantum numbers. Second, data are relatively scarce because of their small production rates and the many difficulties in the experimental measurements. As a result, other alternatives need to be explored. This review summarizes three such approaches that can help disentangle the nature of the many exotic hadrons discovered. In the first approach, based on the molecular interpretations for some exotic states, we study the likely existence of multiplets of hadronic molecules related by various symmetries, such as isospin symmetry, SU(3)-flavor symmetry, heavy quark spin/flavor symmetry, and heavy antiquark diquark symmetry. In the second approach, starting from some hadronic molecular candidates, one can derive the underlying hadron-hadron interactions. With these interactions, one can study related three-body systems and check whether three-body bound states/resonances exist. In the third approach, one can turn to the femtoscopy technique to derive the hadron-hadron interactions, hence inaccessible. This technique provided an unprecedented opportunity to understand the interactions between unstable hadrons.

    hep-phhep-exhep-latnucl-ex+1Phys.Rept.(2025)·218 citations
21. 21*

    Exploring Four Fermion Contact Couplings of a Dark Fermion and an Electron at Hadron Colliders and Direct Detection Experiments

    Kai Ma🇨🇳

    Both collider searches and direct detections are promising approaches to probe fermionic dark matter. In this paper, we study signatures of four-fermion contact operators involving a dark fermion, an electron, and a quark pair. We show that the mono-electron production channel at hadron colliders can provide strong constraints. Associated productions of a charged electron with a photon/jet and missing energy are also studied. Using current LHC data at $\sqrt{s}=13\text{TeV}$, the lower bound on the energy scale of the (axial-)vector operator can reach 12 TeV for a massless dark fermion. This can be further improved to about 24 TeV at the HE-LHC with $\sqrt{s}=25\text{TeV}$ and a total luminosity of $20{\text{ab}}^{-1}$. For direct detections, the signal operators can induce ${\beta }^{\pm }$ decays. For the induced ${\beta }^{-}$ decay, we find that the constraints are weaker than those from collider searches in almost all of the parameter space, and the accessible parameter space has already been excluded by current LHC data. In the case of a relatively heavy dark fermion (a few MeV), the induced ${\beta }^{+}$ decay is more sensitive than collider searches. Despite the advantage of collider searches that a much wider range of dark fermion masses can be investigated, they can also provide complementarity to direct detections.

    hep-phPhys.Dark Univ.(2025)·9 citations
22. 22*

    Minimal solution to the axion isocurvature problem from a nonminimal coupling

    Maximilian Berbig🇪🇸

    The main limitation for preinflationary breaking of Peccei-Quinn (PQ) symmetry is the upper bound on the Hubble rate during inflation from axion isocurvature fluctuations. This leads to a tension between high scale inflation and QCD axions with grand unified theory (GUT) scale decay constants, which reduces the potential for a detection of tensor modes at next generation cosmic microwave background (CMB) experiments. We propose a mechanism that explicitly breaks PQ symmetry via nonminimal coupling to gravity, that lifts the axion mass above the Hubble scale during inflation and has negligible impact on today's axion potential. The initially heavy axion gets trapped at an intermediate minimum during inflation given by the phase of the nonminimal coupling, before it moves to its true $CP$-conserving minimum after inflation. During this stage it undergoes coherent oscillations around an adiabatically decreasing minimum, which slightly dilutes the axion energy density, while still being able to explain the observed dark matter relic abundance. This scenario can be tested by the combination of next generation CMB surveys like CMB-S4 and LiteBIRD with haloscopes such as ABRACADABRA, DMRadio or CASPEr-Electric.

    hep-phastro-ph.COgr-qcPRD(2024)·15 citations
23. 23*

    Cosmic Clues: DESI, Dark Energy, and the Cosmological Constant Problem

    Wen Yin🇯🇵

    Several attempts to solve the cosmological constant problem, which concerns the value of the cosmological constant being extremely smaller than the Standard Model mass scales, have introduced a scalar field with a very flat potential that can be approximated as linear around any given position. The scalar field scans the cosmological constant in such a way that the current small value is explained. Recently, Dark Energy Spectroscopic Instrument (DESI) reported the results of the first year. Combining the data with CMB, Pantheon, Union3, and/or DES-SN5YR, there is a preference or anomaly, indicating that the dark energy in the current Universe slightly deviates from that in the $\Lambda$CDM model and varies over time. In this paper, I show that the simple linear potential of a scalar field that may explain the small cosmological constant can explain the DESI anomaly. In particular, the model proposed by the present author in 2108.04246, which relaxes the cosmological constant by the condition that inflation ends, predicts a time-dependence of the dark energy close to the one favored by the data.

    hep-phastro-ph.GAgr-qcJHEP(2024)·106 citations
24. 24*

    Novel Model-Independent Approach to Explore New Physics in Five-body Semileptonic Decays

    Yao Yu🇨🇳 · Hong-Song Xie🇨🇳 · Han Zhang🇨🇳 · Bai-Cian Ke🇨🇳 · Xiao-Di Zhou🇨🇳 · Peng-Yu Chen🇨🇳

    Substantial contribution of the tensor current in semileptonic decays is regarded as a clear signal for new physics. In this work, we propose a model-independent approach to unambiguously test contribution of the tensor current in semileptonic five-body decays ${\bar{D}}_{(s)}/{\bar{B}}_{(s)}\to V\ell {\bar{\nu }}_{\ell }(\ell =e,\mu ,\tau )$ with $V\to {\pi }^0{\pi }^{+}{\pi }^{-}$, where $V$ denotes vector particles. We derive three parameters associated with the angular asymmetry, which are always equal to one in the Standard Model regardless the data of form factor but will deviate if contribution of the tensor current doesn't vanish. The outcomes have potential applications in precisely testing the Standard Model and searching for new physics. Relevant measurements can be performed using data collected by BESIII, Belle~II, and LHCb.

    hep-phhep-exPRD(2025)·0 citations
25. 25*

    On the Role of Cosmological Gravitational Particle Production in Baryogenesis

    Marcos M. Flores🇫🇷 · Yuber F. Perez-Gonzalez🇬🇧

    We investigate the generation of the baryon asymmetry within the framework of cosmological gra\-vi\-ta\-tional particle production, employing the Bogoliubov approach. We examine two well-known baryogenesis scenarios, namely baryogenesis in Grand Unified Theories (GUT) and leptogenesis, while considering reheating temperatures sufficiently low for thermal processes to be negligible. Considering $\alpha -$attractor T-models for the inflaton potential, we demonstrate that GUT baryogenesis from scalar decays can be successful across a large range of conformal couplings with gravity, without necessitating substantial levels of CP violation. In the case of leptogenesis, we find that the reheating temperature should be $T_{\mathrm{RH}}\lesssim 10^6\mathrm{GeV}$ for right-handed neutrino masses $M_1\lesssim 6\times 10^{12}\mathrm{GeV}$ to generate the observed asymmetry.

    hep-phastro-ph.COgr-qcPRD(2024)·9 citations
26. 26*

    Implications of $B\to K\nu \bar{\nu }$ under Rank-One Flavor Violation hypothesis

    David Marzocca🇮🇹 · Marco Nardecchia🇮🇹 · Alfredo Stanzione🇮🇹 · Claudio Toni🇮🇹

    We study the implications of the observed excess in $B^{+}\to K^{+}\nu \bar{\nu }$ under the assumption of Rank-One Flavour Violation, i.e. that New Physics couples to a single specific direction in flavour space. By varying this direction we perform analyses at the level of the low-energy EFT, the SMEFT, and with explicit mediators such as leptoquarks and colorless vectors ($Z^{\prime }$ and $V^{\prime }$). We study correlations with other flavour, electroweak and collider observables, finding that the most interesting ones are with $K\to \pi \nu \bar{\nu }$, $B_s\to {\mu }^{+}{\mu }^{-}$, meson mixing and the LHC searches in ${\tau }^{+}{\tau }^{-}$ high-energy tails. Among the various mediators, the scalar leptoquarks ${\tilde{R}}_2$ and $S_1$ offer the best fits of the Belle-II excess, while being consistent with the other bounds. On the other hand, colorless vectors are strongly constrained by meson mixing and resonance searches in $pp\to {\tau }^{+}{\tau }^{-}$. In all cases we find that a flavour alignment close to the third generation is generically preferred.

    hep-phEPJC(2024)·39 citations
27. 27*

    Non-Gaussianities and Primordial Black Holes

    Shi Pi🇨🇳

    The most promising mechanism of generating PBHs is by the enhancement of power spectrum of the primordial curvature perturbation, which is usually accompanied by the the enhancement of non-Gaussianity that crucially changes the abundance of PBHs. In this review I will discuss how non-Gaussianity is generated in single field inflation as well as in the curvaton scenario, and then discuss how to calculate PBH mass function and induced gravitational waves (GWs) with such non-Gaussianities. When the PBH abundance is fixed, non-Gaussianity only has mild impact on the spectral shape of the induced GWs, which gives relatively robust predictions in the mHz and nHz GW experiments.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ph+147 citations
28. 28*

    Wess-Zumino-Witten Terms of $Sp$ QCD by Bordism Theory

    Shota Saito🇯🇵

    We investigate the four-dimensional Wess-Zumino-Witten (WZW) terms within the framework of $Sp$ quantum chromodynamics (QCD) using invertible field theory through bordism theory. We present a novel approach aimed at circumventing both perturbative and non-perturbative gauge anomalies on spacetime manifolds endowed with spin structures. We study both ungauged and gauged WZW terms including the problems of the topological consistency of gauged WZW terms.

    ↳ hep-thhep-phJHEP(2024)·2 citations
29. 29*

    The Gravitational Chiral Anomaly at Finite Temperature and Density

    Claudio Corianò🇮🇹 · Mario Cretì🇮🇹 · Stefano Lionetti🇮🇹 · Riccardo Tommasi🇮🇹

    We investigate the gravitational anomaly vertex $⟨TT{J}_5⟩$ (graviton - graviton - axial current) under conditions of finite density and temperature. Through a direct analysis of perturbative contributions, we demonstrate that neither finite temperature nor finite fermion density affects the gravitational chiral anomaly. These results find application in several contexts, from topological materials to the early universe plasma. They affect the decay of any axion or axion-like particle into gravitational waves, in very dense and hot environments.

    ↳ hep-thcond-mat.mes-hallhep-phPRD(2024)·5 citations
30. 30*

    From chiral EFT to perturbative QCD: a Bayesian model mixing approach to symmetric nuclear matter

    A. C. Semposki🇺🇸 · C. Drischler🇺🇸 · R. J. Furnstahl🇺🇸 · J. A. Melendez🇺🇸 · D. R. Phillips🇺🇸

    Constraining the equation of state (EOS) of strongly interacting, dense matter is the focus of intense experimental, observational, and theoretical effort. Chiral effective field theory ($\chi$EFT) can describe the EOS between the typical densities of nuclei and those in the outer cores of neutron stars while perturbative QCD (pQCD) can be applied to properties of deconfined quark matter, both with quantified theoretical uncertainties. However, describing the full range of densities in between with a single EOS that has well-quantified uncertainties is a challenging problem. Bayesian multi-model inference from $\chi$EFT and pQCD can help bridge the gap between the two theories. In this work, we introduce a correlated Bayesian model mixing framework that uses a Gaussian Process (GP) to assimilate different information into a single QCD EOS for symmetric nuclear matter. The present implementation uses a stationary GP to infer this mixed EOS solely from the EOSs of $\chi$EFT and pQCD while accounting for the truncation errors of each theory. The GP is trained on the pressure as a function of number density in the low- and high-density regions where $\chi$EFT and pQCD are, respectively, valid. We impose priors on the GP kernel hyperparameters to suppress unphysical correlations between these regimes. This, together with the assumption of stationarity, results in smooth $\chi$EFT-to-pQCD curves for both the pressure and the speed of sound. We show that using uncorrelated mixing requires uncontrolled extrapolation of at least one of $\chi$EFT or pQCD into regions where the perturbative series breaks down and leads to an acausal EOS. We also discuss extensions of this framework to non-stationary and less differentiable GP kernels, its future application to neutron-star matter, and the incorporation of additional constraints from nuclear theory, experiment, and multi-messenger astronomy.

    ↳ nucl-thastro-ph.HEhep-phPRC(2025)·30 citations
31. 31*

    Constraining solar electron number density via neutrino flavor data at Borexino

    Caroline Laber-Smith🇺🇸 · Eve Armstrong🇺🇸 · A. Baha Balantekin🇺🇸 · Elizabeth K. Jones🇺🇸 · Lily Newkirk🇺🇸 · Amol V. Patwardhan🇺🇸 · Sarah Ranginwala🇺🇸 · M. Margarette Sanchez🇺🇸 · Hansen Torres🇺🇸

    Understanding the physics of the deep solar interior, and the more exotic environs of core-collapse supernovae (CCSN) and binary neutron-star (NS) mergers, is of keen interest in many avenues of research. To date, this physics is based largely on simulations via forward integration. While these simulations provide valuable constraints, it could be insightful to adopt the "inverse approach" as a point of comparison. Within this paradigm, parameters of the solar interior are not output based on an assumed model, but rather are inferred based on real data. We take the specific case of solar electron number density, which historically is taken as output from the standard solar model. We show how one may arrive at an independent constraint on that density profile based on available neutrino flavor data from the Earth-based Borexino experiment. The inference technique's ability to offer a unique lens on physics can be extended to other datasets, and to analogous questions for CCSN and NS mergers, albeit with simulated data.

    ↳ astro-ph.SRastro-ph.HEhep-phPRD(2024)·5 citations
32. 32*

    Lattice determination of the Batalin-Vilkovisky function and the strong running interaction

    A. C. Aguilar🇧🇷 · N. Brito🇵🇹 · M. N. Ferreira🇪🇸 · J. Papavassiliou🇪🇸 · O. Oliveira🇵🇹 · P. J. Silva🇵🇹

    The Batalin-Vilkovisky function is a central component in the modern formulation of the background field method and the physical applications derived from it. In the present work we report on novel lattice results for this particular quantity, obtained by capitalizing on its equality with the Kugo-Ojima function in the Landau gauge. The results of the lattice simulation are in very good agreement with the predictions derived from a continuum analysis based on the corresponding Schwinger-Dyson equations. In addition, we show that an important relation connecting this function with the ghost propagator is fulfilled rather accurately. With the aid of these results, we carry out the first completely lattice-based determination of the process-independent strong running interaction, employed in a variety of phenomenological studies.

    ↳ hep-lathep-phhep-thnucl-thPLB(2024)·5 citations
33. 33*

    Primordial black holes and curvature perturbations from false vacuum islands

    Rong-Gen Cai🇨🇳 · Yu-Shi Hao🇨🇳 · Shao-Jiang Wang🇨🇳

    Recently, much attention has been focused on the false vacuum islands that are flooded by an expanding ocean of true-vacuum bubbles slightly later than most of the other parts of the world. These delayed decay regions will accumulate locally larger vacuum energy density by staying in the false vacuum longer than those already transited into the true vacuum. A false vacuum island with thus acquired density contrast of a super-horizon size will evolve locally from radiation dominance to vacuum dominance, creating a local baby Universe that can be regarded effectively as a local closed Universe. If such density contrasts of super-horizon sizes can ever grow large enough to exceed the threshold of gravitational collapse, primordial black holes will form similar to those collapsing curvature perturbations on super-horizon scales induced by small-scale enhancements during inflation. If not, such density contrasts can still induce curvature perturbations potentially observable today. In this paper, we revisit and elaborate on the generations of primordial black holes and curvature perturbations from delayed-decayed false vacuum islands during asynchronous first-order phase transitions with fitting formulas convenient for future model-independent studies.

    ↳ astro-ph.COgr-qchep-phSCPMA(2024)·41 citations
34. 34*

    First Search for High-Energy Neutrino Emission from Galaxy Mergers

    Subhadip Bouri🇮🇳 · Priyank Parashari🇮🇳 · Mousumi Das🇵🇱 · Ranjan Laha🇮🇳

    The exact sources of high-energy neutrinos detected by the IceCube neutrino observatory still remain a mystery. For the first time, this work explores the hypothesis that galaxy mergers may serve as sources for these high-energy neutrinos. Galaxy mergers can host very high-energy hadronic and photohadronic processes, which may produce very high-energy neutrinos. We perform an unbinned maximum-likelihood-ratio analysis utilizing the galaxy merger data from six catalogs and 10 years of public IceCube muon-track data to quantify any correlation between these mergers and neutrino events. First, we perform the single source search analysis, which reveals that none of the considered galaxy mergers exhibit a statistically significant correlation with high-energy neutrino events detected by IceCube. Furthermore, we conduct a stacking analysis with three different weighting schemes to understand if these galaxy mergers can contribute significantly to the diffuse flux of high-energy astrophysical neutrinos detected by IceCube. We find that upper limits (at $95\%$ CL) of the all flavor high-energy neutrino flux, associated with galaxy mergers considered in this study, at $100$ TeV with spectral index $\Gamma =-2$ are $1.11\times 10^{-18}$, $3.69\times 10^{-19}$ and $1.02\times 10^{-18}$ $\mathrm{Ge}{\mathrm{V}}^{-1}\mathrm{c}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}\mathrm{s}{\mathrm{r}}^{-1}$ for the three weighting schemes. This work shows that these selected galaxy mergers do not contribute significantly to the IceCube detected high energy neutrino flux. We hope that in the near future with more data, the search for neutrinos from galaxy mergers can either discover their neutrino production or impose more stringent constraints on the production mechanism of high-energy neutrinos within galaxy mergers.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-ex+1PRD(2025)·9 citations
35. 35*

    Reconstructing Primordial Black Hole Power Spectra from Gravitational Waves

    Daniel Frolovsky🇷🇺 · Florian Kuhnel🇩🇪 · Ioanna Stamou🇧🇪

    A novel methodology for analysing the relation between the energy density in gravitational waves and primordial power spectra is developed. Focusing on scalar-induced gravitational radiation, this methodology is applied to a number of scenarios for the primordial black hole formation. Being differed from conventional Bayesian approaches, its advantages include directness and computational efficiency, which are crucial for handling the complex data characteristic of gravitational wave research. As an important application, it is demonstrated that this methodology allows for the systematic reconstruction of power spectra across all scenarios using current pulsar timing array data, providing a clear example of its potential in gravitational wave analysis.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·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.