Tue·Jul 9, 2024Tuesday·July 9, 2024

1. 01*

   Factorization for $J/\psi$ leptoproduction at small transverse momentum

   Miguel G. Echevarria🇪🇸 · Samuel F. Romera🇪🇸 · Pieter Taels🇧🇪

   Nonrelativistic Quantum Chromodynamics (NRQCD) breaks down in the region of low transverse momentum, where the transverse momentum of the produced quarkonium state is sensitive to multiple scattering with the incoming hadron and to soft gluon radiation. In this kinematic regime, the transverse-momentum-dependent (TMD) factorization framework is required, promoting the long-distance matrix elements (LDMEs) of NRQCD to the so-called TMD shape functions (TMDShFs), which encode both the soft gluon radiation and the formation of the heavy-quark bound state. In this work, we apply an effective-field theory approach (combining NRQCD and SCET) to the photon-gluon fusion process in inclusive $J/\psi$ leptoproduction. We derive a factorization theorem for the cross section in terms of TMDShFs, compute these quantities at next-to-leading order, establish their evolution, and study their matching onto the corresponding LDMEs in the high-transverse-momentum region. Our results are particularly relevant to the Electron-Ion Collider, where $J/\psi$ leptoproduction can be used to probe gluon transverse-momentum-dependent parton distribution functions (gluon TMDPDFs).

   hep-phJHEP(2024)·17 citations
2. 02*

   Freeze-in as a Complementary Process to Freeze-Out

   Rodrigo Capucha🇵🇹 · Karim Elyaouti🇩🇪 · Margarete Mühlleitner🇩🇪 · Johann Plotnikov🇩🇪 · Rui Santos🇵🇹

   There are many extensions of the Standard Model with a dark matter (DM) candidate obtained via the freeze-out mechanism. It can happen that after all experimental and theoretical constraints are taken into account, all parameter points have a relic density below the experimentally measured value. This means that the models solve only partially the DM problem, and at least one more candidate is needed. In this work we show that it is possible to further extend the model with a DM candidate obtained via the freeze-in mechanism to be in agreement with the relic density experimental measurement. Once the relic density problem is solved with this addition, new questions are raised. This new model with at least two DM candidates could have a freeze-out undetectable DM particle both in direct and indirect detection. This could happen if the freeze-out DM particle would have a very low density. Hence, a collider DM hint via excess in the missing energy with no correspondence in direct and indirect detection experiments, could signal the existence of a Feebly Interacting Massive Particle (FIMP). Conversely, if a DM particle is found and a particular model can explain all observables except the correct relic density, an extension with an extra FIMP would solve the problem. The freeze-in DM candidate, due to the small portal couplings, will not change the remaining phenomenology.

   hep-phJHEP(2024)·7 citations
3. 03*

   Signatures of supermassive charged gravitinos in liquid scintillator detectors

   Adrianna Kruk🇵🇱 · Michał Lesiuk🇵🇱 · Krzysztof A. Meissner🇵🇱 · Hermann Nicolai🇩🇪

   In a previous work [K.A. Meissner and H. Nicolai, Eur. Phys. J. C {\bf 84}, 269 (2024)], two of the present authors have suggested possible experimental ways to search for stable supermassive particles with electric charges of $\text{cO}(1)$ in upcoming underground experiments, in particular the new Jiangmen Underground Neutrino Observatory (JUNO) experiment. In the current paper, we present a detailed analysis of the specific signature of such gravitino-induced events for the JUNO detector and for upcoming liquid argon detectors like DUNE (Deep Underground Neutrino Experiment). The proposed method of detection relies on the ``glow'' produced by photons during the passage of such particles through the detector liquid, which would last for about a few to a few hundred microseconds depending on its velocity and the track. The cross sections for electronic excitation of the main component of the scintillator liquid, namely linear alkylbenzene (LAB), by the passing gravitino are evaluated using quantum-chemical methods. The results show that, if such particles exist, the resulting signals would lead to a unique and unmistakable signature, for which we present event simulations as they would be seen by the JUNO or DUNE photomultipliers. Our analysis brings together two very different research areas, namely fundamental particles physics and the search for a fundamental theory on the one hand, and methods of advanced quantum chemistry on the other.

   hep-phhep-thphysics.chem-phPRResearch(2025)·4 citations
4. 04*

   QCD Masterclass Lectures on Jet Physics and Machine Learning

   Andrew J. Larkoski🇺🇸

   These lectures were presented at the 2024 QCD Masterclass in Saint-Jacut-de-la-Mer, France. They introduce and review fundamental theorems and principles of machine learning within the context of collider particle physics, focused on application to jet identification and discrimination. Numerous examples of binary discrimination in jet physics are studied in detail, including $H\to b\bar{b}$ identification in fixed-order perturbation theory, generic one-versus two-prong discrimination with parametric power counting techniques, and up versus down quark jet classification by assuming the central limit theorem, isospin conservation, and a convergent moment expansion of the single particle energy distribution. Quark versus gluon jet discrimination is considered in multiple contexts, from using additive, infrared and collinear safe observables, to using hadronic multiplicity, and to including measurements of the jet charge. While many of the results presented here are well known, some novel results are presented, the most prominent being a parametrized expression for the likelihood ratio of quark versus gluon discrimination for jets on which hadronic multiplicity and jet charge are simultaneously measured. End-of-lecture exercises are also provided.

   hep-phhep-exhep-thnucl-ex+1EPJC(2024)·20 citations
5. 05*

   Helicity-changing Decays of Cosmological Relic Neutrinos

   Jihong Huang🇨🇳 · Shun Zhou🇨🇳

   In this paper, we examine the possibility that massive neutrinos are unstable due to their invisible decays ${\nu }_i^{}\to {\nu }_j^{}+\varphi$, where ${\nu }_i^{}$ and ${\nu }_j^{}$ (for $i,j=1,2,3$) are any two of neutrino mass eigenstates with masses $m_i^{}>m_j^{}$ and $\varphi$ is a massless Nambu-Goldstone boson, and explore the implications for the detection of cosmological relic neutrinos in the present Universe. First, we carry out a complete calculation of neutrino decay rates in the general case where the individual helicities of parent and daughter neutrinos are specified. Then, the invisible decays of cosmological relic neutrinos are studied and their impact on the capture rates on the beta-decaying nuclei (e.g., ${\nu }_e^{}+{}^3\mathrm{H}\to {}^3\mathrm{He}+e^{-}$) is analyzed. The invisible decays of massive neutrinos could substantially change the capture rates in the PTOLEMY-like experiments when compared to the case of stable neutrinos. In particular, we find that the helicity-changing decays of Dirac neutrinos play an important role whereas those of Majorana neutrinos have no practical effects. However, if a substantial fraction of heavier neutrinos decay into the lightest one, the detection of relic neutrinos will require a much higher energy resolution and thus be even more challenging.

   hep-phastro-ph.COhep-exJCAP(2024)·6 citations
6. 06*

   Gluon Sivers function from forward exclusive ${\chi }_{c1}$ photoproduction on unpolarized protons

   Sanjin Benic🇭🇷 · Adrian Dumitru🇺🇸 · Leszek Motyka🇵🇱 · Tomasz Stebel🇵🇱

   Exclusive production of a ${\chi }_{c1}$ axial vector quarkonia in photon-proton scattering at high energies requires a $C$-odd $t$-channel exchange. In the limit of vanishing momentum transfer this occurs either via the exchange of a photon, the Primakoff process, where the spin of the proton does not change. For axial-vector meson production, as a consequence of the Landau-Yang theorem, the Primakoff cross section is finite as $t\to 0$. Alternatively, a $C$-odd spin dependent Odderon can be exchanged, which involves a spin flip of the proton. The resulting cross section is related to the square of the collinear trigluon correlator or the $k_{\perp }$-moment of the gluon Sivers function. Using two models for the gluon Sivers function from the literature we compute the ratio of Sivers to Primakoff cross sections and the angular coefficient ${\lambda }_{\theta }$ governing the angular distribution of the ${\chi }_{c1}\to J/\psi +\gamma$ decay as functions of $x$. We point out that these observables constrain the magnitude of the gluon Sivers function at small $x$ which could be accessed in electron-proton scattering and ultraperipheral proton-proton and nucleus-proton collisions.

   hep-phPRD(2025)·7 citations
7. 07*

   Representation-theoretical characterization of canonical custodial symmetry in NHDM potentials

   R. Plantey🇳🇴 · M. Aa. Solberg🇳🇴

   By considering the basis-covariant constituents of N-Higgs-doublet potentials, we derive necessary and sufficient conditions for canonical SO(4)_C Custodial Symmetry (CS) of potentials with N>2 doublets, based on representation-theoretical and geometrical relations. In essence, our characterization relates the presence of canonical CS to basis-covariant vectors corresponding to particular bases of the defining representation of the orthogonal Lie algebras. For N=3,4 and 5, the conditions demand little computational effort to be evaluated, and we provide practical algorithms that may be efficiently implemented in a computer program, for deciding whether or not a potential is custodial-symmetric.

   hep-phhep-thmath-phmath.MPNPB(2024)·1 citation
8. 08*

   Impact of finite volume on kaon, antikaon, and $\varphi$ meson masses and decay width in asymmetric strange hadronic matter

   Zeeshan Ahmad🇮🇳 · Nisha Chahal🇮🇳 · Arvind Kumar🇮🇳 · Suneel Dutt🇮🇳

   In the present work, we investigate the impact of finite volume on the in-medium properties of kaons ($K^{+}$, $K^0$) and antikaons ($K^{-}$, $\overline{K^0}$), and $\varphi$ mesons in the isospin asymmetric strange hadronic medium at finite density and temperature. We use the chiral SU(3) hadronic mean-field model, which accounts for the interactions between baryons through the exchange of scalar ($\sigma ,\zeta ,\delta$) and vector ($\omega$, $\rho$, $\varphi$) fields. To investigate the effects of finite volume, we apply the multiple reflection expansion (MRE) technique for calculations of the density of states. The non-strange scalar field $\sigma$ shows significant variation in an asymmetric medium, while the strange scalar field $\zeta$ shows good dependency in the strange medium. We use the medium-modified masses of kaons and antikaons calculated using the chiral SU(3) model to obtain the masses and decay width of $\varphi$ mesons in finite volume hadronic medium. To obtain the masses and decay widths of $\varphi$ mesons, an effective Lagrangian approach with $\varphi$$K$$\bar{K}$ interactions at one-loop level is used in the present work. We obtain the effective masses and decay widths in the finite volume matter, for the spherical geometry of the medium with Neumann and Dirichlet boundary conditions as well as for the cubic geometry. The finite volume effects are found to be appreciable at high baryon densities.

   hep-phnucl-thPTEP(2025)·4 citations
9. 09*

   Probing axion-like particles in leptonic decays of heavy mesons

   Gang Yang🇨🇳 · Tianhong Wang🇨🇳 · Guo-Li Wang🇨🇳

   We study the possibility of finding the axion-like particles (ALPs) through the leptonic decays of heavy mesons. The Standard Model (SM) predictions of the branching ratios of the leptonic decays of heavy mesons are less than the corresponding experimental upper limits. This provides some room for the existence of decay channels, of which the ALP is one of the products. Three scenarios are considered: First, the ALP is only coupled to one single charged fermion, namely, the quark, the antiquark, or the charged lepton; second, the ALP is only coupled to quark and antiquark with the same strength; and third, the ALP is coupled to all the charged fermions with the same strength. The constraints of the coupling strength in different scenarios are obtained by comparing the experimental data of the branching ratios of leptonic decays of $B^{-}$, $D^{+}$, and $D_s^{+}$ mesons with the theoretical predictions achieved by using the Bethe-Salpeter (BS) method. These constraints are further applied to predict the upper limits of the leptonic decay processes of the $B_c^{-}$ meson in which the ALP participates.

   hep-phCPC(2025)·2 citations
10. 10*

    Pion photoproduction of nucleon excited states with Hamiltonian effective field theory

    Yu Zhuge🇨🇳 · Zhan-Wei Liu🇨🇳 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺

    We refine our previous calculation of multipole amplitude $E_{0+}$ for pion photoproduction process, $\gamma N\to \pi N$. The treatment of final-state interactions is based upon an earlier analysis of pion-nucleon scattering within Hamiltonian effective field theory, supplemented by incorporating contributions from the $N^{\ast }(1650)$ and the $K\Lambda$ coupled channel. The contribution from the bare state corresponding to the $N^{\ast }(1650)$ significantly enhances our results. Additionally, we also compute the multipole amplitude $M_{1-}$, which is of direct relevance to the Roper resonance. The results are comparable with other dynamical coupled channel models, even though the contribution from the bare state (interpreted as a 2$s$ excitation) in this channel is small because of its large mass.

    hep-phnucl-thPRD(2024)·14 citations
11. 11*

    An interpretation of scalars in SO(32)

    Alejandro Rivero🇪🇸

    We propose an interpretation for the adjoint representation of the $SO(32)$ group to classify the scalars of a generic Supersymmetric Standard Model having just three generations of particles, via a flavour group $SU(5)$. We show that this same interpretation arises from a simple postulate of self-consistence of composites for these scalars. The model looks only for colour and electric charge, and it pays the cost of an additional chiral $+4/3$ quark per generation.

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

    Connecting pseudo-Nambu-Goldstone dark matter with pseudo-Dirac neutrinos in a left-right symmetry model

    Sumit Biswas🇺🇸 · Vishnu P.K. · Anil Thapa🇺🇸

    Stringent constraints from the dark matter (DM) direct detection experiments can be naturally evaded for a pseudo-Nambu-Goldstone boson (pNGB) DM. We propose a realization of pNGB DM in the context of a left-right symmetric model, wherein the neutrinos are pseudo-Dirac in nature. The Dirac mass term for neutrinos arises from two-loop quantum corrections, whereas the Majorana mass terms are generated from Planck-induced corrections. This class of model also provides a parity solution to the strong CP problem without the need for an axion. We show an interesting correlation between the lifetime of the DM and the mass-squared differences between active and sterile neutrinos while maintaining a solution to the strong CP problem.

    hep-phhep-exPRD(2025)·6 citations
13. 13*

    Probing the nature of the anticharmed-strange pentaquark states: mass spectra, decays, and magnetic moments

    Xuejie Liu🇨🇳 · Yue Tan🇨🇳 · Xiaoyun Chen🇨🇳 · Dianyong Chen🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

    Within the framework of the quark delocalization color screening model, a systematic investigation of the anticharmed-strange pentaquark system is performed using the resonance group method. The currently estimations predict three bound states with estimated masses to be 2886 MeV, 3039 MeV, and 3153 MeV, respectively. Additionally, three resonance states are identified in various scattering phase shifts processes. Among them, two resonance states $\Sigma D$ and ${\Sigma }^{\ast }{D}^{\ast }$ with quantum number $\frac{1}{2}({\frac{1}{2}}^{-})$ are detected in channels $N{D}_s^{\ast }$ and $ND$, and $\Sigma D^{\ast }$ and $\Lambda D$, with masses and decay widths of ($M_R=3053\sim 3055$ MeV, $T_{total}=13.0\sim 13.4$ MeV) and ($M_R=3389\sim 3390$ MeV, $T_{total}=10.4$ MeV), respectively. In the $\Lambda D^{\ast }$ and $\Sigma D^{\ast }$ channels, a resonance state with quantum number $\frac{1}{2}({\frac{3}{2}}^{-})$ is discovered, with its mass and decay width being $3250\sim 3252$ MeV and 4.4 MeV, respectively. These predicted pentaquark states have $\bar{c}snnn$ quark compositions, allowing them to be recognized as genuine pentaquark states. To validate these predictions, it is expected that upcoming experiments will further explore the predicted resonance and bound states in these possible decay channels.

    hep-phnucl-thPRD(2024)·3 citations
14. 14*

    Resonant leptogenesis in minimal $U(1{)}_X$ extensions of the Standard Model

    Arindam Das🇯🇵 · Yuta Orikasa🇨🇿

    We investigate a general $U(1{)}_X$ scenario where we introduce three generations of Standard Model (SM) singlet Right Handed Neutrinos (RHNs) to generate the light neutrino mass through the seesaw mechanism after the breaking of $U(1{)}_X$ and electroweak symmetries. In addition to that, a general $U(1{)}_X$ scenario involves an SM-singlet scalar field and due to the $U(1{)}_X$ symmetry breaking the mass of a neutral beyond the SM (BSM) gauge boson $Z^{\prime }$ is evolved. The RHNs, being charged under $U(1{)}_X$ scenario, can explain the origin of observed baryon asymmetry through the resonant leptogenesis process. Applying observed neutrino oscillation data we study $Z^{\prime }$ and BSM scalar induced processes to reproduce the observed baryon asymmetry. Hence we estimate bounds on the $U(1{)}_X$ gauge coupling $(g_X)$ and the mass of the $Z^{\prime }$ $(M_{Z^{\prime }})$ for different $U(1{)}_X$ charges and benchmark masses of RHN and SM-singlet scalar. Finally we compare our results with limits obtained from the existing limits from LEP-II and LHC. We find that depending on the $U(1{)}_X$ charges, the masses of RHNs and SM-singlet scalar resonant leptogenesis could provide stronger limit on $g_X$ for $M_{Z^{\prime }}>5.8$ TeV which could be probed by high energy scattering experiment in future.

    hep-phhep-exPLB(2025)·12 citations
15. 15*

    Studying the $\Xi (2030)$ as a predominantly ${\bar{K}}^{\ast }\Sigma$ molecular state

    Jing-wen Feng🇨🇳 · Cai Cheng · Yin Huang🇨🇳

    Since its discovery in 1977, the spin-parity of $\Xi (2030)$ has not been fully determined experimentally. The latest Particle Data Group (PDG) listing suggests it may be a baryon with $J=5/2$. Therefore, studying the mass spectrum and decay properties of $\Xi (2030)$ has become a current hot topic to definitively establish its spin-parity. As the three-quark model fails to explain $\Xi (2030)$, we previously proposed it may be a molecule primarily composed of ${\bar{K}}^{}\Sigma$ with $J^P=5/2^{+}$, based on its mass spectrum study. To verify its molecular state interpretation, this work proposes studying the strong decays of $\Xi (2030)$ assuming it is a $P$-wave $J^P=5/2^{+}$ meson-baryon molecule predominantly composed of ${\bar{K}}^{}\Sigma$. We calculated all experimentally measured two-body and three-body final state decay widths of $\Xi (2030)$, including $\Xi (2030)\to \bar{K}\Lambda ,\bar{K}\Sigma ,\pi \Xi ,\pi {\Xi }^{\ast }$, and $\Xi (2030)\to \pi \pi \Xi ,\pi \bar{K}\Sigma ,\pi \bar{K}\Lambda$. The results indicate that both the total decay width and partial decay widths agree well with experimental values within the error margins. This supports that $\Xi (2030)$ is a molecule with spin-parity $J^P=5/2^{+}$, predominantly composed of ${\bar{K}}^{\ast }\Sigma$. Compared to the experimental central values, our results are slightly smaller, which suggests that $\Xi (2030)$ may contain additional components besides meson-baryon molecular components, such as three quark structures.

    hep-phnucl-th0 citations
16. 16*

    Modified hybrid inflation in no-scale SUGRA with suppressed $R$-symmetry breaking

    Qian Wan🇨🇳 · Da-Xin Zhang🇨🇳

    A well-motivated cosmological hybrid inflation scenario based on no-scale SUGRA is considered. It is demonstrated that an extra suppressed $R$-symmetry breaking term $S^n$ with $n\ge 4$ needs to be included in order to realize successful inflation. The resulting potential is found to be similar (but not identical) to the one in the Starobinsky inflation model. A relatively larger tensor-to-scalar ratio $r\sim 10^{-2}$ and a spectral index $n_s\approx 0.965$ are obtained, which are approximately independent of $n$.

    hep-phEPJC(2025)·2 citations
17. 17*

    Collision energy dependence of elliptic flow of identified hadrons in heavy-ion collisions using the PHSD model

    B. Towseef · M. Farooq · V. Bairathi · B. Waseem · S. Kabana · S. Ahmad

    We report the first predictions of elliptic flow ($v_2$) of identified hadrons at mid-rapidity ($|y|<$ 1.0) in Au+Au collisions at $E_{lab}=$ 6.7, 8, 11, and 25 A GeV using the Parton Hadron String Dynamics (PHSD) model. The transverse momentum ($p_{\mathrm{T}}$) dependence of identified hadron $v_2$ in different centrality intervals (0-10%, 10-40%, and 40-80%) are shown. A clear centrality dependence of $v_2(p_{\mathrm{T}})$ is observed for particles at $E_{lab}=$ 25 and 11 A GeV, while the centrality dependence becomes weaker for particles at $E_{lab}=$ 8 and 6.7 A GeV. Within the PHSD model, the number of constituent quark (NCQ) scaling of $v_2$ approximately follows in Au+Au collisions at all beam energies. A collision energy ($\sqrt{s_{NN}}$) dependence of $\pi$, $K$, and $p$ $v_2$ is studied in comparison with available published experimental data in the beam energy range of 6-25 A GeV. These predictions will help in interpreting the data from the forthcoming Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) and Multi-Purpose Detector (MPD) at the Nuclotron-based Ion Collider facility (NICA).

    hep-phhep-exPLB(2024)·1 citation
18. 18*

    Neutrino transition magnetic moment in the $U(1{)}_X$SSM

    Long Ruan🇨🇳 · Shu-Min Zhao🇨🇳 · Ming-Yue Liu🇨🇳 · Xing-Yu Han🇨🇳 · Xi Wang🇨🇳 · Xing-Xing Dong🇨🇳

    This paper investigates the neutrino transition magnetic moment in the $U(1{)}_X$SSM. $U(1{)}_X$SSM is the $U(1)$ extension of Minimal Supersymmetric Standard Model (MSSM) and its local gauge group is extended to $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y\times U(1{)}_X$. To obtain this model, three singlet new Higgs superfields and right-handed neutrinos are added to the MSSM, which can explain the results of neutrino oscillation experiments. The neutrino transition magnetic moment is induced by electroweak radiative corrections. By applying effective Lagrangian method and on-shell scheme, we study the associated Feynman diagrams and the transition magnetic moment of neutrinos in the model. We fit experimental data for neutrino mass variances and mixing angle. Based on the range of data selection, the influences of different sensitive parameters on the results are analysed. The numerical analysis shows that many parameters have an effect on the neutrino transition moment, such as $g_X$, $M_2$, ${\lambda }_H$ and $g_{YX}$. For our numerical results, the order of magnitude of ${\mu }_{ij}^M/{\mu }_B$ is around $10^{-20}$ $\sim$ $10^{-19}$.

    hep-phCPC(2025)·1 citation
19. 19*

    $P_c(4457)$ interpreted as a $J^P=1/2^{+}$ state by ${\bar{D}}^0{\Lambda }_c^{+}(2595)$-${\pi }^0{P}_c(4312)$ interaction

    Jin-Zi Wu🇨🇳 · Jin-Yi Pang🇨🇳 · Jia-Jun Wu🇨🇳

    $P_c(4457)$ has been discovered over five years, but the parity of this particle remains undetermined. In this letter we propose a new interpretation for $P_c(4457)$, which is the state generated from the coupled-channel ${\bar{D}}^0{\Lambda }_c^{+}(2595)$ and ${\pi }^0{P}_c(4312)$ since they can exchange an almost on-shell ${\Sigma }_c^{+}$. In this scenario, the parity of $P_c(4457)$ will be positive, which is different from the candidate of the bound state of ${\bar{D}}^{\ast }{\Sigma }_c$. The main decay channel of $P_c(4457)$ in this model is $P_c(4312)\pi$. We propose three processes ${\Lambda }_b^0\to J/\psi K_{s}p{\pi }^{-}$, ${\Lambda }_b^0\to J/\psi K^{-}p{\pi }^0$, and ${\Lambda }_b^0\to J/\psi p{\pi }^{-}{\pi }^{+}{K}^{-}$ to verify $P_c(4457)\to P_c(4312)\pi$.

    hep-phChin.Phys.Lett.(2024)·7 citations
20. 20*

    Dark Sector Tunneling Field Potentials for a Dark Big Bang

    Richard Casey🇺🇸 · Cosmin Ilie🇺🇸

    All of the significant evidence for dark matter observed thus far has been through its gravitational interactions. After 40 years of direct detection experiments, the parameter space for Weakly Interacting Massive Particles (WIMPs) as dark matter candidates is rapidly approaching the neutrino floor. In this light, we consider a dark sector that is strongly decoupled from the visible sector, interacting exclusively through gravity. In this model, proposed by Freese and Winkler (arXiv:2302.11579), dark matter can be produced through a first-order phase transition in the dark sector dubbed the Dark Big Bang. In this study we fully determine the allowed region of parameter space for the tunneling potential that leads to the realization of a Dark Big Bang and is consistent with all experimental bounds available.

    hep-phastro-ph.COPRD(2024)·3 citations
21. 21*

    Relic Abundance of Dark Matter with $\Delta$(54) Flavor Symmetry

    Hrishi Bora🇮🇳 · Ng. K. Francis🇮🇳 · Shawan Kumar Jha🇮🇳

    In this work we discuss the neutrino phenomenology in a $\Delta (54)$ discrete flavor symmetry and evaluate the relic abundance of dark matter (DM) and active neutrino-DM mixing angle considering various cosmological constraints. We introduced two Standard Model Higgs particles along with vector-like fermions and a new particle (S) which is a gauge singlet in the Standard Model. This modification leads to a mass matrix that diverges from the tribimaximal neutrino mixing pattern resulting in a non-zero reactor angle (${\theta }_{13}$). We also incorporated a $Z_2\otimes Z_3\otimes Z_4$ symmetry for the specific interactions in our model. The additional particle S is a sterile neutrino which is considered to be a probable dark matter candidate with mass in keV range.

    hep-phhep-thJ.Subatomic Part.Cosmol.(2024)·1 citation
22. 22*

    Electroweak corrections to $gg\to HH$: Factorizable contributions

    Joshua Davies🇬🇧 · Kay Schönwald🇨🇭 · Matthias Steinhauser🇩🇪 · Hantian Zhang🇩🇪

    In these proceedings, we consider the factorizable contributions of the two-loop electroweak corrections to Higgs boson pair production at the Large Hadron Collider. We discuss the classification of factorizable diagrams and their renormalization. Compact analytic results for the renormalized form factors are presented in a computer-readable form.

    hep-phPoS(2024)·16 citations
23. 23*

    T violation at a future neutrino factory

    Ryuichiro Kitano🇯🇵 · Joe Sato🇯🇵 · Sho Sugama🇯🇵

    We study the possibility of measuring T (time reversal) violation in a future long baseline neutrino oscillation experiment. By assuming a neutrino factory as a staging scenario of a muon collider at the J-PARC site, we find that the ${\nu }_e\to {\nu }_{\mu }$ oscillation probabilities can be measured with a good accuracy at the Hyper-Kamiokande detector. By comparing with the probability of the time-reversal process, ${\nu }_{\mu }\to {\nu }_e$, measured at the T2K/T2HK experiments, one can determine the CP phase $\delta$ in the neutrino mixing matrix if $|\sin (\delta )|$ is large enough. The determination of $\delta$ can be made with poor knowledge of the matter density of the earth as T violation is almost insensitive to the matter effects. The comparison of CP and T-violation measurements, $\grave{a}la$ the CPT theorem, provides us with a non-trivial check of the three neutrino paradigm based on the quantum field theory.

    hep-phhep-exJHEP(2024)·12 citations
24. 24*

    Revisiting for maximal flavor violating $Z_{e\mu }^{{}^{\prime }}$ and its phenomenology constraints

    Jia Liu🇨🇳 · Muyuan Song🇨🇳 · Haohao Zhang🇨🇳

    Lepton flavor violation (LFV), observed conclusively in neutrino oscillations, remains a pivotal area of investigation due to its absence in the Standard Model (SM). Beyond the Standard Model (BSM) physics explores charged lepton flavor violation (CLFV), particularly through new particle candidates such as the $Z^{\prime }$. This article focuses on maximal LFV interactions facilitated by the $Z^{\prime }$ boson, specifically targeting its off-diagonal interactions with the first and second generations of charged and neutral leptons. In our ultraviolet (UV) model for the origin of the $Z^{\prime }$, inspired by the work of [R.Foot \textit{et al.,}, Phys.Rev. D50 (1994) 4571-4580], we utilize the discrete $Z_2$ symmetry to investigate the maximal LFV mediated by the $Z^{\prime }$ between the muon ($\mu$) and electron ($e$) arising from the additional scalars. This symmetry prohibits flavor-conserving interactions between $Z^{\prime }$ and ${\mu }^{+}{\mu }^{-},e^{+}{e}^{-}$. In conjunction with collider, $(g-2{)}_{\mu },(g-2{)}_e$, inverse $\mu$ decay, Muonium-to-Antimuonium conversion and LFV decay constraints, we provide forecasts for anticipated limits derived from processes such as ${\nu }_{\mu }N\to {\nu }_e{\mu }^{+}{e}^{-}N$ in neutrino trident experiments like the DUNE search at the first time. These limits highlight the prospective scope and significance of LFV investigations within these experimental frameworks. Within the mass range of 0.01 GeV to 10 GeV, the most stringent limit arises from $B(\mu \to e+X+\gamma )$ when $M_{Z^{\prime }}<m_{\mu }$, while $\Delta a_e$ provides effective constraints as $M_{Z^{\prime }}$ approaches 10 GeV. Looking ahead, the proposed Muonium-to-Antimuonium Conversion Experiment (MACE) is expected to impose the most stringent constraints on Muonium-to-Antimuonium oscillation, improving sensitivity by about one order of magnitude against $\Delta a_e$.

    hep-phJHEP(2024)·5 citations
25. 25*

    Extraction of fissile isotope antineutrino spectra using feedforward neural network

    Jian Chen🇨🇳 · Jun Wang🇨🇳 · Wei Wang🇨🇳 · Yuehuan Wei🇨🇳

    The precise measurement of the antineutrino spectra produced by isotope fission in reactors is of great significance for studying neutrino oscillations, refining nuclear databases, and addressing the reactor antineutrino anomaly. In this paper, we report a method that utilizes a feedforward neural network (FNN) model to decompose the prompt energy spectrum observed in a short-baseline reactor neutrino experiment and extract the antineutrino spectra produced by the fission of major isotopes such as ${}^{235}$U, ${}^{238}$U, ${}^{239}$Pu, and ${}^{241}$Pu in the nuclear reactor. We present two training strategies for the model and compare them with the traditional ${\chi }^2$ minimization method by applying them to the same set of pseudo-data corresponding to a total exposure of $(2.9\times 5\times 1800)\mathrm{G}{\mathrm{W}}_{\mathrm{th}}\cdot \mathrm{tonnes}\cdot \mathrm{days}$. The results show that the FNN model not only converges faster and better during the fitting process but also achieves relative errors of less than 1\% in the $2-8$ MeV range in the extracted spectra, outperforming the ${\chi }^2$ minimization method. The feasibility and superiority of this method were validated in the study.

    hep-phNucl.Sci.Tech.(2025)·4 citations
26. 26*

    Maximum Entropy Method for Valence Quark Distributions in Exotic Hadrons: A Study of the $Z_c(3900)$ Case

    Chengdong Han🇨🇳 · Xiaopeng Wang🇨🇳 · Wei Kou🇨🇳 · Xurong Chen🇨🇳

    In this study we demonstrate the application of the Maximum Entropy Method (MEM) to determine the valence quark distribution of exotic hadrons. Our investigation yields three key findings. Firstly, we observe a significant shift towards smaller Bjorken scale $x$ in the peak position of the valence quark distribution for hadrons with an increasing number of valence quarks, consistent with previous results by Kawamura and Kumano. Secondly, assuming that the $Z_c(3900)$ initially consists of four valence quarks, we employ MEM to determine its initial valence quark distribution, estimating a radius of $r_c=1.276$ fm at an extremely low resolution scale $Q^2$. Furthermore, we identify a notable discrepancy between our computed charge form factor $G_c(q)$ at leading order and the outcomes of hadron molecular state calculations. We propose that this form factor can be extracted from the QCD counting rule cross-section, which is grounded in Generalized Distribution Amplitudes (GDA) linked to the multi-quark states.

    hep-phEPJC(2024)·1 citation
27. 27*

    Light nuclei photoproduction in relativistic heavy ion ultraperipheral collisions

    Jin-Yu Hu🇨🇳 · Shuo Lin🇨🇳 · Shi Pu🇨🇳 · Qun Wang🇨🇳

    We have investigated light nuclei pair photoproduction in relativistic heavy ion ultraperipheral collisions. As a first attempt, we employ our previously developed quantum electrodynamics model, which incorporates a wave-packet description of initial nuclei, to compute the cross section for proton-antiproton pair photoproduction. The effective vertex for the photon and proton interaction is chosen based on studies of two-photon exchange effects in hadron physics. We present the transverse momentum, invariant mass, and azimuthal angle distributions of proton-antiproton pairs at $\sqrt{s_{NN}}=200$ GeV in Au+Au ultraperipheral collisions. We observe a $\cos (2\varphi )$ modulation and an almost negligible $\cos (4\varphi )$ modulation in the azimuthal angle distribution. Our studies helps us better understand the matter generated by light.

    hep-phnucl-th4 citations
28. 28*

    Constraining $|V_{cs}|$ and physics beyond the Standard Model from exclusive (semi)leptonic charm decays

    Carolina Bolognani🇳🇱 · Méril Reboud🇫🇷 · Danny van Dyk🇬🇧 · K. Keri Vos🇳🇱

    We study the available data on exclusive leptonic and semileptonic $c\to s{\ell }^{+}\nu$ decays within the Standard Model and beyond. Our analysis accounts for theory correlations between the relevant hadronic matrix elements through application of dispersive bounds. We find that, within a global analysis, the dispersive bounds are generally well respected and only mildly affect the extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|V_{cs}|$. Assuming Standard Model dynamics, we obtain $$|V_{cs}|=0.957\pm 0.003,$$ which is compatible with the HFLAV/PDG reference value $|V_{cs}|=0.975\pm 0.006$ at the $2.7\sigma$ level. Our findings lead to significant deficits in the second-row and second-column unitarity relations of the CKM matrix. Allowing for beyond the SM contributions in the Weak Effective Theory, we find very strong constraints on potential (pseudo)scalar and tensor effects. However, the data still permits sizeable CP-violating right-handed currents.

    hep-phJHEP(2024)·11 citations
29. 29*

    Non-Standard Interactions of Supernova Neutrinos and Mass Ordering Ambiguity at DUNE

    Sudip Jana🇩🇪 · Yago Porto🇧🇷

    We show that non-standard neutrino interactions (NSI) can notably modify the pattern of resonant flavor conversion of neutrinos within supernovae and significantly impact the neutronization burst signal in forthcoming experiments such as the Deep Underground Neutrino Experiment (DUNE). The presence of NSI can invert the energy levels of neutrino matter eigenstates and even induce a new resonance in the inner parts close to the proto-neutron star. We demonstrate how DUNE can use these new configurations of energy levels to have sensitivity to NSIs down to $\mathcal{O}(0.1)$. We also elucidate how the effect may result in a puzzling confusion of normal and inverted mass orderings by highlighting the emergence or vanishing of the neutronization peak, which distinguishes between the two mass orderings. Potential implications are analyzed thoroughly.

    hep-phastro-ph.HEastro-ph.SRhep-ex+1JCAP(2025)·9 citations
30. 30*

    Spontaneous CP Breaking in a QCD-like Theory

    Csaba Csáki🇺🇸 · Maximilian Ruhdorfer🇺🇸 · Taewook Youn🇺🇸

    We examine the phase structure of a QCD-like theory at $\bar{\theta }=\pi$ obtained from supersymmetric $SU(N)$ QCD perturbed by a small amount of supersymmetry breaking via anomaly mediation (AMSB QCD). The spectrum of this theory matches that of QCD at the massless level, though the superpartners are not decoupled. In this theory it is possible to nail down the phase structure at $\bar{\theta }=\pi$ as a function of the quark masses and the number of flavors $F$. For one flavor we find that there is a critical quark mass, below which CP is unbroken, while above the critical mass CP is spontaneously broken. At the critical mass there is a second-order phase transition along with a massless ${\eta }^{\prime }$. We are able to analytically solve for the minima and the critical mass for $N=2,3$ as well as for the large $N$ limit, while for other $N$ one can find numerical results. For two flavors, we find that CP is always broken as long as the quark masses are equal and non-zero, however there is a non-trivial phase boundary for unequal quark masses, which we find numerically. For $F\ge 3$ we obtain an intricate phase boundary which reproduces the various quark mass limits. All our results are in agreement with the predictions for ordinary QCD that were based on anomaly matching arguments for generalized symmetries and the effective chiral Lagrangian. We also briefly comment on the domain wall solutions first discussed by Draper, and are able to present analytic results for the simplest case of $SU(2)$ with one flavor.

    hep-phhep-thJHEP(2024)·4 citations
31. 31*

    Indirect Searches for Ultraheavy Dark Matter in the Time Domain

    David E. Kaplan🇺🇸 · Xuheng Luo🇺🇸 · Ngan H. Nguyen🇺🇸 · Surjeet Rajendran🇺🇸 · Erwin H. Tanin🇺🇸

    Dark matter may exist today in the form of ultraheavy composite bound states. Collisions between such dark matter states can release intense bursts of radiation that includes gamma-rays among the final products. Thus, indirect-detection signals of dark matter may include unconventional gamma-ray bursts. Such bursts may have been missed not necessarily because of their low arriving gamma-ray fluxes, but rather their briefness and rareness. We point out that intense bursts whose non-detection thus far are due to the latter can be detected in the near future with existing and planned facilities. In particular, we propose that, with slight experimental adjustments and suitable data analyses, imaging atmospheric Cherenkov telescopes (IACTs) and Pulsed All-sky Near-infrared and Optical Search for Extra-Terrestrial Intelligence (PANOSETI) are promising tools for detecting such rare, brief, but intense bursts. We also show that if we assume these bursts originate from collisions of dark matter states, IACTs and PANOSETI can probe a large dark matter parameter space beyond existing limits. Additionally, we present a concrete model of dark matter that produces bursts potentially detectable in these instruments.

    hep-phastro-ph.COastro-ph.GAastro-ph.HEPRD(2025)·11 citations
32. 32*

    Explanation of the excesses in associated di-photon production at 152 GeV in 2HDM

    Sumit Banik🇨🇭 · Andreas Crivellin🇨🇭

    Statistically significant excesses exist at around 152 GeV in associated di-photon production ($\gamma \gamma +X$) in the sidebands of SM Higgs analyses of ATLAS (using the full run-2 dataset). They are most pronounced in the single-$\tau$, missing-transverse-energy, four-jet and $⩾1\ell +⩾1b$-jet channels ($\approx 3\sigma$) and can be explained by the Drell-Yan production of new Higgs bosons, i.e. $pp\to W^{\ast }\to H^{\pm }{H}^0$. We first examine the excesses in a simplified model approach, considering that $H^{\pm }$ decays to $\tau \nu$, $WZ$ or $tb$. Both the $\tau \nu$ and $tb$ decay modes individually lead to a significance of $⪅4\sigma$ while for $WZ$ one can obtain at most $3.5\sigma$. This is because the decays of $WZ$ lead to multiple leptons contributing to the two-lepton channel which does not show an excess at 152 GeV. Next, we consider two-Higgs-doublet models where the charged Higgs does not decay to $WZ$ at tree-level, finding a significance of $⪆4\sigma$ for a branching ratio of the new neutral Higgs to photons of $\approx$2%. Even though this branching fraction is quite sizable, it can be obtained in composite models or via the Lagrangian term ${\lambda }_6{H}_1^{†}{H}_1{H}_2^{†}{H}_1+h.c.$ breaking the commonly imposed $Z_2$ symmetry.

    hep-phhep-exnucl-thJHEP(2024)·14 citations
33. 33*

    Circularly polarized photon emission from magnetized chiral plasmas

    Xinyang Wang🇨🇳 · Igor A. Shovkovy🇺🇸

    We investigate the emission of circularly polarized photons from a magnetized quark-gluon plasma with nonzero quark-number and chiral charge chemical potentials. These chemical potentials qualitatively influence the differential emission rates of circularly polarized photons. A nonzero net electric charge density, induced by quark-number chemical potentials, enhances the overall emission of one circular polarization over the other, while a nonzero chiral charge density introduces a spatial asymmetry in the emission with respect to reflection in the transverse plane. The signs of the electrical and chiral charge densities determine which circular polarization dominates overall and whether the emission preferentially aligns with or opposes the magnetic field. Based on these findings, we propose that polarized photon emission is a promising observable for characterizing the quark-gluon plasma produced in heavy-ion collisions.

    hep-phnucl-thPRD(2024)·10 citations
34. 34*

    Angular distributions of Drell-Yan leptons in the TMD factorization approach

    Sara Piloneta🇪🇸 · Alexey Vladimirov🇪🇸

    We present a comprehensive study of the angular structure functions for Drell-Yan leptons in $Z/\gamma$-boson production within the framework of the transverse momentum dependent (TMD) factorization theorem, including kinematic power corrections (KPCs). We find good agreement with the data in the applicability region of the TMD factorization theorem. The inclusion of KPCs allows us to describe all angular coefficients in a frame-independent manner using only the leading-twist TMD distributions: the unpolarized and the Boer-Mulders functions. The value of the Boer-Mulders function is determined using the ATLAS measurement of the $A_2$ angular coefficient. The analysis is performed at N${}^4$LL perturbative order. Additionally, we discuss the technical implementation and impact of KPCs on the phenomenology of TMD distributions.

    hep-phJHEP(2024)·27 citations
35. 35*

    Chameleon Mechanism in Scalar Nonmetricity Cosmology

    Andronikos Paliathanasis🇿🇦

    We investigate the dynamics and the phase-space evolution for the scalar nonmetricity cosmology with a Chameleon mechanism. In particular, we consider a spatially flat Friedmann--Lema\^ıtre--Robertson--Walker geometry and within the framework of scalar nonmetricity theory, we consider a generalization of the Brans-Dicke theory in nonmetricity gravity. Introducing a pressureless gas as the matter source, we also incorporate a coupling function responsible for the interaction. Our findings reveal that the choice of connection in nonmetricity gravity significantly impacts the interaction between the scalar field and the matter source. For one particular connection, we discover the absence of asymptotic solutions with a nontrivial interacting component. More precisely, in this scenario, the matter source does not directly interact with the scalar field; however, there is an interaction with the dynamical degrees of freedom provided by the connection.

    ↳ gr-qcastro-ph.COhep-phAnnals Phys.(2024)·13 citations
36. 36*

    Statistical Production of $B_c$ Mesons in Heavy-Ion Collisions at the LHC Energy

    Shouxing Zhao🇨🇳 · Min He🇨🇳

    The recombination production of $B_c$ mesons in heavy-ion collisions at the LHC energy is facilitated by the abundant and highly thermalized charm ($c$) quarks transported in the deconfined medium created. We study the production of $B_c$ mesons via $c$ and bottom ($b$) quark recombination in a statistical fashion by placing $B_c$ in the position of a member of the family of open $b$ hadrons, which allows us to make quantitative predictions for the modifications of the production fraction ($f_c$) of $B_c$ mesons and its relative production to $B$ mesons in $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV Pb-Pb collisions with respect to proton-proton ($pp$) collisions at the same energy. The statistical production yield of $B_c$ mesons is converted into the transverse momentum ($p_T$) distribution with the shape computed from resonance recombination using the $c$- and $b$-quark phase space distributions that have been simulated via Langevin diffusion and constrained by open $c$- and $b$-hadron observables. Supplemented with the component fragmented from $b$-quark spectrum that dominates at high $p_T$, the total $p_T$ spectrum of $B_c$ mesons is obtained and converted into the $p_T$ dependent nuclear modification factor ($R_{\mathrm{AA}}$). Both $f_c$ and the integrated $R_{\mathrm{AA}}$ exhibit a $\sim 5$-fold enhancement in central Pb-Pb collisions relative to the $pp$ reference. Comparison with data measured by the CMS experiment shows decent agreement within theoretical and experimental uncertainties.

    ↳ nucl-thhep-phnucl-exPLB(2025)·6 citations
37. 37*

    Volume effect on the extraction of sound velocity in high-energy nucleus-nucleus collisions

    Jing-An Sun🇨🇳 · Li Yan🇨🇳

    The determination of the speed of sound in quark-gluon plasma is a crucial aspect of understanding the properties of strongly interacting matter created in relativistic heavy-ion collisions. In this study, we investigate the impact of initial-state fluctuations on the extraction of the speed of sound in a quark-gluon plasma in the ultra-central collisions. By employing the TRENTo model for simulating initial conditions, we demonstrate that these fluctuations lead to sizable volume effect, which in turn corrects the measured values of the sound velocity. With respect to realistic conditions of high-energy heavy-ion experiments, we provide quantitative estimate of these corrections.

    ↳ nucl-thhep-phnucl-exPLB(2025)·9 citations
38. 38*

    Surface and curvature tensions of cold dense quark matter: a term-by-term analysis within the Nambu-Jona-Lasinio model

    A. G. Grunfeld🇦🇷 · M. F. Izzo Villafañe🇦🇷 · G. Lugones🇧🇷

    In this paper, we conduct a thorough investigation of the surface and curvature tensions, $\sigma$ and $\gamma$, of three-flavor cold quark matter using the Nambu-Jona-Lasinio (NJL) model with vector interactions. Our approach ensures both local and global electric charge neutrality, as well as chemical equilibrium under weak interactions. By employing the multiple reflection expansion formalism to account for finite size effects, we explore the impact of specific input parameters, particularly the vector coupling constant ratio ${\eta }_V$, the radius $R$ of quark matter droplets, as well as charge-per-baryon ratio $\xi$ of the finite size configurations. We focus on the role of the contributions of each term of the NJL Lagrangian to the surface and curvature tensions in the mean field approximation. We find that the total surface tension exhibits two different density regimes: it remains roughly constant at around $100\mathrm{MeV}\mathrm{f}{\mathrm{m}}^{-2}$ up to approximately $2-4$ times the nuclear saturation density, and beyond this point, it becomes a steeply increasing function of $n_B$. The total surface and curvature tensions are relatively insensitive to variations in $R$ but are affected by changes in $\xi$ and ${\eta }_V$. We observe that the largest contribution to $\sigma$ and $\gamma$ comes from the regularized divergent term, making these quantities significantly higher than those obtained within the MIT bag model.

    ↳ nucl-thastro-ph.HEastro-ph.SRhep-phUniverse(2025)·3 citations
39. 39*

    Positivity properties of scattering amplitudes

    Johannes Henn🇩🇪 · Prashanth Raman🇩🇪

    We investigate positivity properties in quantum field theory (QFT). We provide evidence,and in some case proofs, that many building blocks of scattering amplitudes, and in some cases the full amplitudes, satisfy an infinite number of positivity conditions: the functions, as well as all their signed derivatives, are non-negative in a specified kinematic region. Such functions are known as completely monotonic(CM) in the mathematics literature. A powerful way to certify complete monotonicity is via integral representations. We thus show that it applies to planar and non-planar Feynman integrals possessing a Euclidean region,as well as to certain Euler integrals relevant to cosmological correlators and stringy integrals. This implies that in particular that many basic building blocks of perturbation theory, such as master integrals, can be chosen to be completely monotone. We also discuss two pathways for showing complete monotonicity for full amplitudes. One is related to properties of the analytic S-matrix. The other one is a close connection between the CM property and Positive Geometry. Motivated by this, we investigate positivity properties in planar maximally supersymmetric Yang-Mills theory. We present evidence, based on known analytic multi-loop results, that the CM property extends to several physical quantities in this theory. This includes the (suitably normalized) finite remainder function of the six-particle maximally-helicity-violating (MHV) amplitude, four-point scattering amplitudes on the Coulomb branch,four-point correlation functions, as well as the angle-dependent cusp anomalous dimension. Our findings are however not limited to supersymmetric theories. It is shown that the CM property holds for the QCD and QED cusp anomalous dimensions, to three and four loops, respectively. We comment on open questions, and on possible numerical applications of complete monotonicity.

    ↳ hep-thhep-phJHEP(2025)·26 citations
40. 40*

    Primordial acoustic turbulence: three-dimensional simulations and gravitational wave predictions

    Jani Dahl🇫🇮 · Mark Hindmarsh🇫🇮 · Kari Rummukainen🇫🇮 · David Weir🇫🇮

    Gravitational waves (GWs) generated by a first-order phase transition at the electroweak scale are detectable by future space-based detectors like LISA. The lifetime of the resulting shock waves plays an important role in determining the intensity of the generated GWs. We have simulated decaying primordial acoustic turbulence in three dimensions and make a prediction for the universal shape of the energy spectrum by using its self-similar decay properties and the shape of individual shock waves. The shape for the spectrum is used to determine the time dependence of the fluid kinetic energy and the energy containing length scale at late times. The inertial range power law is found to be close to the classically predicted $k^{-2}$ and approaches it with increasing Reynolds number. The resulting model for the velocity spectrum and its decay in time is combined with the sound shell model assumptions about the correlations of the velocity field to compute the GW power spectrum for flows that decay in less than the Hubble time. The decay is found to bring about a convergence in the spectral amplitude and the peak power law that leads to a power law shallower than the $k^9$ of the stationary case.

    ↳ gr-qchep-phphysics.flu-dynPRD(2024)·19 citations
41. 41*

    Primordial gravitational waves in horizon cosmology and constraints on entropic parameters

    Sergei D. Odintsov🇪🇸 · Simone D'Onofrio🇪🇸 · Tanmoy Paul🇮🇳

    The hallmark of the 4-parameter generalized entropy is that it can represent various known entropies proposed so far for suitable limits of the parameters, and thus the 4-parameter generalized entropy can be applied on additive as well as on non-additive systems. Thereafter the proposal of the generalized entropy, it becomes important to constrain the corresponding parameters. In the present work, we intend to do this from the perspective of primordial gravitational waves (GWs) generated during inflation. In the background level, the generalized entropy successfully drives a viable and smooth evolution of the universe, particularly from inflation to reheating followed by a radiation era, for certain ranges of the entropic parameters. Consequently we investigate whether such viable ranges of the entropic parameters (coming from the background level) allow the primordial GWs spectrum to pass through the sensitivity curves of various GWs observatories. Therefore, if the future observatories can detect the signal of primordial GWs, then our theoretical expectation carried in the present work may provide a possible tool for the measurement of the generalized entropic parameters.

    ↳ gr-qchep-phhep-thPRD(2024)·13 citations
42. 42*

    A generalized method of constraining Warm Inflation with CMB data

    Umang Kumar🇮🇳 · Suratna Das🇮🇳

    A thorough MCMC analysis of any inflationary model against the current cosmological data is essential for assessing the validity of such a model as a viable inflationary model. Warm Inflation, producing both thermal and quantum fluctuations, yield a complex form of scalar power spectrum, which, in general, cannot be directly written as a function of the comoving wavenumber $k$, an essential step to incorporate the primordial spectra into CAMB to do an MCMC analysis through CosmoMC/Cobaya. In this paper, we devised an efficient generalized methodology to mould the WI power spectra as a function of $k$, without the need of slow-roll approximation of the inflationary dynamics. The methodology is directly applicable to any Warm Inflation model, including the ones with complex forms of the dissipative coefficient and the inflaton potential.

    ↳ astro-ph.COgr-qchep-phJCAP(2024)·18 citations
43. 43*

    Revisiting the Ultraviolet Tail of the Primordial Gravitational Wave

    Shi Pi🇨🇳 · Misao Sasaki🇯🇵 · Ao Wang🇨🇳 · Jianing Wang🇨🇳

    High-frequency primordial gravitational waves (PGWs) with wave numbers larger than the Hubble parameter at the end of inflation are originated from the ultraviolet (UV) modes, which are never stretched out of the horizon. Such a UV tail of the PGW energy spectrum has a spurious logarithmic divergence. We study the origin of such a divergence, and find that it comes from the instantaneous inflation-to-post-inflation transition, which can be removed by considering a finite duration. For the first time, we obtain a semi-analytical expression for the PGW energy spectrum. We find that the UV tail decays exponentially, while the decay rate depends solely on the transition rate. When there is a stiff post-inflationary stage, the enhanced PGW displays a characteristic spectral shape of power-law increasing and exponential decaying. We propose a fitting formula which can be used for signal searching.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2024)·22 citations
44. 44*

    Exact Diffeomorphism in Warped Space

    Haiying Cai🇰🇷

    In this paper, we study the manifestation of exact diffeomorphism in warped extra dimension, with an emphasis on the Randall-Sundrum model. Utilizing the covariant form of variation $\delta g_{MN}={\nabla }_M{\xi }_N+{\nabla }_N{\xi }_M$, we derive the nonlinear transformation rules for the metric fields in the unitary gauge. As an off-shell symmetry, diffeomorphism governs the interaction structure by connecting the neighboring orders of bulk action expansions. Our analysis unveils that an on-shell diffeomorphism exists prior to radion stabilization, but is broken by the Goldberger-Wise mechanism. This on-shell symmetry enforces a mass-related equation $F^{\prime }-A^{\prime }G=0$ to eliminate one degree of freedom, while ensuring the 5D action invariant up to a surface term. Therefore, we conjecture that the on-shell diffeomorphism actually protects the radion field from acquiring mass.

    ↳ hep-thhep-ph0 citations
45. 45*

    Cosmological cutting rules for Bogoliubov initial states

    Diptimoy Ghosh🇮🇳 · Enrico Pajer🇬🇧 · Farman Ullah🇮🇳

    The field theoretic wavefunction in cosmological spacetimes has received much attention as a fundamental object underlying the generation of primordial perturbations in our universe. Assuming an initial Bunch-Davies state, unitary time evolution implies an infinite set of cutting rules for the wavefunction to all orders in perturbation theory, collectively known as the cosmological optical theorem. In this work, we generalise these results to the case of Bogoliubov initial states, accounting for both parity-even and parity-odd interactions. We confirm our findings in a few explicit examples, assuming IR-finite interactions. In these examples, we preserve scale invariance by adiabatically turning on interactions in the infinite past rather than imposing a Bogoliubov state at some finite initial time. Finally, we give a prescription for computing Bogoliubov wavefunction coefficients from the corresponding Bunch-Davies coefficients for both n-point contact and four-point exchange diagrams.

    ↳ hep-thgr-qchep-phSciPost Phys.(2025)·27 citations
46. 46*

    Thermal False Vacuum Decay Is More Than It Seems

    Dalila Pîrvu🇨🇦 · Andrey Shkerin🇨🇦 · Sergey Sibiryakov🇨🇦

    We study the decay of a thermally excited metastable vacuum in classical field theory using real-time numerical simulations. We find a significantly lower decay rate than predicted by standard thermal theory at moderate temperatures, $E_b/T\sim 10$, where $E_b$ is the critical bubble energy. The discrepancy is due to the violation of thermal equilibrium during the critical bubble nucleation and is reduced if thermalization is enhanced by introduction of dissipation and thermal noise. We formulate a condition for the system to remain in equilibrium during the nucleation process and show that it is generally violated in weakly coupled field theories. Nevertheless, we argue that the violation of thermal equilibrium becomes irrelevant for the false vacuum decay rate at sufficiently low temperatures and the standard thermal rate is recovered.

    ↳ hep-thastro-ph.COcond-mat.stat-mechhep-ph16 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.