Thu·Jan 30, 2025Thursday·January 30, 2025

1. 01*

   Exploring Dimuon Higgs Decay in an Extended Scotogenic Model

   Pablo Escribano🇪🇸 · Víctor Martín Lozano🇪🇸 · Sebastián Norero🇨🇱 · Avelino Vicente🇪🇸

   We investigate the dimuon Higgs decay $h\to {\mu }^{+}{\mu }^{-}$ in the context of an extended Scotogenic model. The model introduces a singlet complex scalar in addition to the standard Scotogenic scalar doublet and singlet fermions, charged under a dark ${\mathbb{Z}}_2$ symmetry. By exploring the one-loop contributions, we show that the model allows for sizable deviations in the Higgs dimuon decay rate, quantified by the quotient $R_{\mu \mu }=\text{Br}(h\to {\mu }^{+}{\mu }^{-})/\text{Br}(h\to {\mu }^{+}{\mu }^{-}{)}_{\text{SM}}$. Crucially, these deviations comply with experimental limits, including those on $\text{Br}({\mu }^{+}\to e^{+}\gamma )$ and $\text{Br}(h\to \gamma \gamma )$. Such deviations can be tested and constrained by future precision measurements at the LHC.

   hep-phJHEP(2025)·1 citation
2. 02*

   Transverse momentum distributions at large-$x$

   Oscar del Rio🇪🇸 · Alexei Prokudin🇺🇸 · Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇪🇸

   We investigate the collinear matching of transverse momentum dependent (TMD) distributions at large values of $x$, computing and resumming the leading large-$x$ asymptotics for matching coefficients. The large-$x$ resummation is done directly within TMD distributions, ensuring the process-independence of the result. The derived resummation formulas are valid for all TMD distributions (except the pretzelosity). Their application improves perturbative convergence, provides practical estimation for unknown higher-order contributions, and sets restrictions for the nonperturbative part of models. Using the known anomalous dimensions, resummation can reach N${}^3$LL, often exceeding the accuracy of known coefficient functions.

   hep-phhep-thJHEP(2025)·6 citations
3. 03*

   The highest energy cosmic rays from superheavy dark matter particles

   E.V. Arbuzova🇷🇺

   It is commonly accepted that high energy cosmic rays up to $10^{19}$ eV can be produced in catastrophic astrophysical processes. However the source of a few observed events with higher energies remains mysterious. We propose that they may originate from decay or annihilation of ultra heavy particles of dark matter. Such particles naturally appear in some models of modified gravity related to Starobinsky inflation.

   hep-phastro-ph.HEPoS(2025)·1 citation
4. 04*

   Particle number diffusion in second-order relativistic dissipative hydrodynamics with momentum-dependent relaxation time

   Sunny Kumar Singh🇮🇳 · Samapan Bhadury🇵🇱 · Manu Kurian🇮🇳 · Vinod Chandra🇮🇳

   This article explores particle number diffusion in relativistic hydrodynamics using kinetic theory with a modified collision kernel that incorporates the momentum dependence of the particle relaxation time. Starting from the Boltzmann equation within the extended relaxation time approximation (ERTA), we derive second-order evolution equations for the dissipative number current and calculate the associated transport coefficients. The sensitivity of transport coefficients to the particle momentum dependence of the collision time scale of the microscopic interactions in the hot QCD medium is analyzed. For a conformal, number-conserving system, we compare the ERTA-modified transport coefficients for particle diffusion with exact results derived from scalar field theory. With an appropriate parameterization of the relaxation time, we demonstrate the consistency of our analysis and assess the degree of agreement of the results with the exact solutions from scalar field theory. The relaxation times for the shear and number diffusion evolution equations are seen to be distinct in general when the momentum dependence of the relaxation time is taken into consideration.

   hep-phnucl-thPRD(2025)·6 citations
5. 05*

   Light Higgs in the Georgi Machacek Model: neutral or charged?

   Swagata Ghosh🇮🇳

   The ATLAS and CMS experiments at the LHC, as well as the LEP and Tevatron, observed the existence of a light SM-like Higgs boson with mass about 95 GeV. These experiments also record the evidences of a light charged Higgs boson with mass less than the top-quark mass. The Georgi-Machacek (GM) model consists of six charged Higgs, one CP-odd and one CP-even Higgs besides the SM Higgs and the SM-like Higgs bosons. Considering the theoretical constraints along with the $\sqrt{s}=13$ TeV Higgs signal strengths, this paper shows that the presence of the 95 GeV SM-like Higgs boson disfavours the presence of the other eight low-mass (below $160$ GeV) Higgs. This also triggers a high triplet vev above $40$ GeV.

   hep-ph6 citations
6. 06*

   Updated constraints on triplet vev in the Georgi Machacek model

   Swagata Ghosh🇮🇳

   The Georgi-Machacek model containing singly as well as doubly charged Higgs bosons besides more than one neutral Higgs bosons preserves the custodial symmetry at the tree level. In addition to the doublet vacuum expectation value (vev) $v_1$ this model has one triplet vev $v_2$, which was most strongly bounded from the above as a function of the custodial triplet mass $m_3$ previously by the $b\to s\gamma$ data. The observed data from the ATLAS and CMS experiments at the LHC for $\sqrt{s}=13$ TeV for the channels $pp\to t\bar{t}$, $t\to H^{+}b$, $H^{+}\to c\bar{s}$, ${\tau }^{+}{\nu }_{\tau }$ for the low mass charged Higgs set new limits on the triplet vev as a function of light charged Higgs boson afterward. Subsequent ATLAS data for the decay $H^{\pm }\to {\tau }^{\pm }{\nu }_{\tau }$ updates the limit on $v_2$ from the above as a function of $m_3$. The present above limits on $v_2$ is now updated to $6.3-13.1$ GeV from the previous value of $7.8-17.4$ GeV for the light custodial triplet mass $m_3$ ranging from $130$ to $160$ GeV.

   hep-ph4 citations
7. 07*

   Multi-Lepton Jets from Quadruple $Z^{\prime }$ via the Higgs Decay at LHC

   Jinmian Li🇨🇳 · Takaaki Nomura🇨🇳 · Kei Yagyu🇯🇵

   We investigate multi-lepton jet events from the decay of the 125 GeV Higgs boson ($h$) into quadruple new gauge bosons $(Z^{\prime })$ at the LHC. Such an exotic decay is realized via the process of $h\to \varphi \varphi \to Z^{\prime }{Z}^{\prime }{Z}^{\prime }{Z}^{\prime }$ with new scalar boson $\varphi$ in models with an additional $U(1)$ gauge symmetry. Charged leptons coming from the $Z^{\prime }$ decay tend to be observed as lepton-jets rather than isolated leptons when the masses of $Z^{\prime }$ and $\varphi$ are smaller than $\mathcal{O}$(10) GeV, because of the highly-boosted effects. Performing the signal and background analyses, we find that the branching ratio of $h\to 4Z^{\prime }$ is maximally constrained to be smaller than of order $10^{-6}$ ($10^{-7}$) by using the muonic-lepton jets assuming the integrated luminosity of 140 fb${}^{-1}$ (3000 fb${}^{-1}$) at LHC. For lighter $Z^{\prime }$ ($<2m_{\mu }$), we can use the electronic-lepton jets instead of the muon-jets, by which the upper limit on the branching ratio is obtained to be of order $10^{-6}$-$10^{-5}$. These bounds can be converted into the constraint on model parameters such as a mixing angle between $h$ and $\varphi$. It is shown that stronger bounds on the mixing angle are obtained in the dark photon case as compared with the previous constraints given by flavor experiments and the Higgs decay $h\to Z^{\prime }{Z}^{\prime }$ in the mass range of $m_{Z^{\prime }}\lesssim 10$ GeV.

   hep-phJHEP(2025)·3 citations
8. 08*

   Heavy-hadron production based on $k_t$-factorization with scale-dependent fragmentation functions

   F. E. Barattini🇨🇱 · C. O. Dib🇨🇱 · B. Guiot🇨🇱

   We present a comprehensive study of heavy-hadron production, including $D$ and $B$ mesons, heavy baryons, and the $B_c$ meson. Our calculations are based on the $k_t$-factorization and scale-dependent fragmentation functions, completing the program of implementing this formalism within a variable-flavor-number scheme, as initiated in Ref. Phys.Rev.D 104 (2021) 9. Special emphasis is placed on the gluon-to-heavy-hadron contribution, which improves the description of data at small transverse momenta. Finally, we explore and compare different factorization schemes. We achieve the non-trivial task of providing a reasonable description of all the data considered in this study with a factorization scheme fixed once and for all.

   hep-phJHEP(2025)·7 citations
9. 09*

   Bottom quark forward-backward asymmetry at the future electron-positron collider FCC-ee

   Marina Cobal🇮🇹 · Giovanni Guerrieri🇮🇹 · Hamzeh Khanpour🇮🇷 · Giancarlo Panizzo🇮🇹 · Michele Pinamonti🇮🇹 · Laura Pintucci🇮🇹 · Leonardo Toffolin🇮🇹

   The Standard Model (SM) prediction for the \PZ-boson pole $b$-quark forward-backward (FB) asymmetry is: $(A_{FB}^{0,b}{)}_{th}=0.1030\pm 0.0002$. The LEP electron-positron collider measured instead $A_{FB}^{0,b}=0.0992\pm 0.0016$, value which presents the largest discrepancy with any of the SM predictions as of today. All the $A_{FB}^b$ measurements performed at LEP suffered however of an important statistical uncertainty and of different sources of systematic uncertainties. This study shows that the proposed high-luminosity electron-positron collider FCC-ee, collecting orders of magnitude more data at the \PZ-pole than LEP, will significantly reduce the statistical uncertainties on the measurement of $A_{FB}^{0,b}$, thus allowing us to shed further light on this tension.

   hep-phhep-ex3 citations
10. 10*

    Self-consistent analysis for the ${\eta }_c\to \gamma \gamma$ process

    Sheng-Quan Wang🇨🇳 · Zhu-Yu Ren🇨🇳 · Jian-Ming Shen🇨🇳 · Xing-Gang Wu🇨🇳 · Leonardo Di Giustino🇮🇹 · Stanley J. Brodsky🇺🇸

    The next-to-next-to-leading-order (NNLO) pQCD predictions for both the decay width and the transition form factor in the ${\eta }_c\to \gamma \gamma$ process, based on nonrelativistic QCD (NRQCD), deviate from precise experimental measurements. These significant discrepancies have cast doubt on the applicability of NRQCD to charmonium processes. In this paper, we analyze the ${\eta }_c\to \gamma \gamma$ process by applying the Principle of Maximum Conformality (PMC), a systematic method for eliminating renormalization scheme and scale ambiguities. The PMC renormalization scales are determined by absorbing the non-conformal $\beta$ terms which govern the behavior of the QCD running coupling via the Renormalization Group Equation. We obtain the PMC scale $Q_{\star }=4.49m_c$ for the ${\eta }_c\to \gamma \gamma$ decay width. Even after using the PMC method, the convergence of the pQCD series is still poor, which indicates the importance of uncalculated NNNLO and higher-order terms. The resulting value for ${\Gamma }_{{\eta }_c\to \gamma \gamma }$ is in agreement with the Particle Data Group's reported value of ${\Gamma }_{{\eta }_c\to \gamma \gamma }=5.1\pm 0.4$ keV within the bounds of uncertainties. Moreover, the transition form factor obtained using the PMC is also in good agreement with precise experimental measurements. The application of the PMC suggests a potential resolution to ${\eta }_c\to \gamma \gamma$ puzzle and supports the applicability of NRQCD to charmonium processes.

    hep-phhep-exPRD(2025)·4 citations
11. 11*

    Feasibility study of true muonium observation with the existing Belle-II dataset

    Ruben Gargiulo🇮🇹 · Elisa Di Meco🇮🇹 · Stefano Palmisano🇮🇹

    True muonium (${\mu }^{+}{\mu }^{-}$) is one of the cleanest bound states, being composed only of leptons, along with true tauonium and positronium. Unlike the latter, true muonium and true tauonium have not been observed so far. This article shows that the spin-0 state of true muonium (para-TM), decaying into two photons, can be observed at a discovery level of significance in the dataset already collected by the Belle-II experiment at the ${\rm Y}(4S)$ peak, with certain assumptions on systematic uncertainties. Para-TM is produced via photon-photon fusion, and its observation is based on the detection of the photon pair resulting from its decay, on top of the continuum background due predominantly to light-by-light scattering. Trigger, acceptance and isolation cuts, along with calorimeter resolution and reconstruction efficiency, are taken into account during the Monte Carlo simulation of both signal and background. In order to separate signal and background, a machine learning method, based on extremely randomized trees, is trained on simulated events. Finally, the expected statistical significance of TM observation is evaluated, taking into account systematic uncertainties in a parametric fashion.

    hep-phhep-exPRD(2025)·8 citations
12. 12*

    Bayesian Inference of the Critical Endpoint in 2+1-Flavor System from Holographic QCD

    Liqiang Zhu🇨🇳 · Xun Chen🇨🇳 · Kai Zhou🇩🇪 · Hanzhong Zhang🇨🇳 · Mei Huang🇨🇳

    We present a Bayesian holographic model constructed by integrating the equation of state and baryon number susceptibility at zero chemical potential from lattice QCD. The model incorporates error estimates derived from lattice data. With this model, we systematically investigate the thermodynamic properties of the 2+1-flavor QCD system. Using Bayesian Inference, we perform precise calibration of the model parameters and determined the critical endpoint (CEP) position under the maximum a posterior (MAP) estimation to be $(T^c,{\mu }_B^c)=(0.0859\mathrm{GeV},0.742\mathrm{GeV})$. Additionally, we predict the CEP positions within 68\% and 95\% confidence levels, yielding $(T^c,{\mu }_B^c{)}_{68\%}$=$(0.0820\text{–}0.0889,0.71\text{–}0.77)\mathrm{GeV}$ and $(T^c,{\mu }_B^c{)}_{95\%}$=$(0.0816\text{–}0.0898,0.71\text{–}0.79)\mathrm{GeV}$, respectively. Moreover, to validate the reliability and predictive power of our approach, we conduct a comprehensive comparison between our predictions and potential CEP locations proposed by other theoretical models. This work not only establishes a novel Bayesian framework for holographic modeling but also provides valuable insights and theoretical support for exploring phase transitions in strongly-interacting matter under extreme conditions.

    hep-phPRD(2025)·28 citations
13. 13*

    Implications of the first CONUS+ measurement of coherent elastic neutrino-nucleus scattering

    Valentina De Romeri🇪🇸 · Dimitrios K. Papoulias🇪🇸 · Gonzalo Sanchez Garcia🇪🇸

    The CONUS+ collaboration has reported their first observation of coherent elastic neutrino-nucleus scattering (CE$\nu$NS). The experiment uses reactor electron antineutrinos and germanium detectors with recoil thresholds as low as $160\mathrm{e}{\mathrm{V}}_{\text{ee}}$. With an exposure of $327$ kg $\times$ d, the measurement was made with a statistical significance of $3.7\sigma$. We explore several physics implications of this observation, both within the standard model and in the context of new physics. We focus on a determination of the weak mixing angle, nonstandard and generalized neutrino interactions both with heavy and light mediators, neutrino magnetic moments, and the up-scattering of neutrinos into sterile fermions through the sterile dipole portal and new mediators. Our results highlight the role of reactor-based \cevns~experiments in probing a vast array of neutrino properties and new physics models.

    hep-phPRD(2025)·36 citations
14. 14*

    Direct Search signal of two-component Dark Matter

    Subhaditya Bhattacharya🇮🇳 · Dipankar Pradhan🇮🇳

    How do we know if the dark sector consists of more than one dark matter (DM) component is an important question, for which the answer is not very definite. In this article we study such a possibility in context of direct DM search. It was pointed out earlier in a model independent analysis that a kink in the nuclear recoil energy spectrum may indicate to the presence of two DM components. However, realising one such model was difficult due to experimental constraints. Here we propose and study a model containing a vector boson DM and a scalar DM, aided by a light scalar mediator, where a kink in the nuclear recoil spectrum arises after addressing individual relic densities, direct search limits, collider constraints and theoretical limits. We find out the allowed parameter space of the model and those regions likely to show such distinctive signal.

    hep-ph2 citations
15. 15*

    Dark matter in the scale-invariant 3-3-1-1 model

    Alex G. Dias🇧🇷 · Kristjan Kannike🇪🇪 · Niko Koivunen🇪🇪 · Júlio Leite🇪🇸 · Vinícius Padovani🇧🇷 · B. L. Sánchez-Vega🇧🇷

    We propose a scale-invariant model with the 3-3-1-1 gauge symmetry that features universal seesaw for all fermion masses. The discrete remnant of the gauge group, the matter parity, stabilizes a fermionic dark matter candidate. The scalar sector contains two triplets, the minimum number to break the 3-3-1 symmetry, and two scalar singlets. With the help of additional vector-like quarks, the universal implementation of the see-saw mechanism across all fermion sectors provides a partial explanation for the observed hierarchy of masses for charged leptons, neutrinos, and quarks. We identify the lightest $P_M$-odd fermion, $f_{\mathrm{d}}$, as a viable dark matter candidate. This fermion satisfies the relic density constraint and the spin-independent constraints within the mass range $160\text{GeV}\lesssim m_{f_{\mathrm{d}}}\lesssim 520$ GeV . This range depends on the symmetry-breaking scale $v_{\chi }$ with a lower bound $v_{\chi }\gtrsim 3.6$ TeV due to LEP bounds on the ${\rho }_0$ parameter. Spin-independent scattering cross-sections for $f_{\mathrm{d}}$ align with experimental limits from LZ and PandaX-4T, with some regions of the parameter space nearing the sensitivity of upcoming experiments, such as XLZD and PandaX-xT, which offers promising opportunities for detection.

    hep-phPRD(2025)·5 citations
16. 16*

    The Fermi function and the neutron's lifetime

    Peter Vander Griend🇺🇸 · Zehua Cao🇺🇸 · Richard Hill🇺🇸 · Ryan Plestid🇺🇸

    The traditional Fermi function ansatz for nuclear beta decay describes enhanced perturbative effects in the limit of large nuclear charge $Z$ and/or small electron velocity $\beta$. We define and compute the quantum field theory object that replaces this ansatz for neutron beta decay, where neither of these limits hold. We present a new factorization formula that applies in the limit of small electron mass, analyze the components of this formula through two loop order, and resum perturbative corrections that are enhanced by large logarithms. We apply our results to the neutron lifetime, supplying the first two-loop input to the long-distance corrections. Our result can be summarized as \begin{equation*} \tau_n \times |V_{ud}|^2\big[1+3\lambda^2\big]\big[1+\Delta_R\big] = \frac{5263.284(17)\,{\rm s}} {1 + 27.04(7)\times 10^{-3} }~, \end{equation*} with $|V_{ud}|$ the up-down quark mixing parameter, ${\tau }_n$ the neutron's lifetime, $\lambda$ the ratio of axial to vector charge, and ${\Delta }_R$ the short-distance matching correction. We find a shift in the long-distance radiative corrections compared to previous work, and discuss implications for extractions of $|V_{ud}|$ and tests of the Standard Model.

    hep-phnucl-exnucl-thPLB(2025)·15 citations
17. 17*

    Analytic next-to-leading order Yukawa and Higgs boson self-coupling corrections to $gg\to HH$ at high energies

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

    We consider electroweak corrections to Higgs boson pair production, taking into account the top quark Yukawa and Higgs boson self couplings. Using differential equations we compute a deep expansion of all master integrals in the high-energy limit and present analytic results for the two-loop box-type form factors. We show that precise numerical results can be obtained even for relatively small values of the Higgs boson transverse momentum. We compare against recent numerical results and find good agreement.

    hep-phJHEP(2025)·22 citations
18. 18*

    Quark matter at four loops: hardships and how to overcome them

    A. Kärkkäinen🇫🇮 · P. Navarrete🇫🇮 · M. Nurmela🇫🇮 · R. Paatelainen🇫🇮 · K. Seppänen🇫🇮 · A. Vuorinen🇫🇮

    Knowledge of the pressure of cold and dense quark matter (QM) is known to significantly constrain the equation of state of neutron-star matter, a quantity playing a key role in deciphering the stars' internal structure. In this work, we make important progress towards determining the last unknown contribution to the pressure at Next-to-Next-to-Next-to-Leading Order (N3LO) in the strong coupling constant ${\alpha }_s$, available through the sum of all four-loop vacuum diagrams of dense Quantum Chromodynamics. We demonstrate the cancellation of both the covariant gauge parameter and all infrared (IR) divergences in the sum, showcasing the effective-field-theory paradigm in action. For the remaining IR-finite four-loop integrals, we demonstrate the efficacy of the dense Loop Tree Duality method -- a novel numerical framework for multiloop calculations in thermal field theory. Together, our results show that completing the N3LO pressure of cold QM is no longer merely possible but for the first time concretely within reach.

    hep-phPRL(2025)·19 citations
19. 19*

    $\Lambda$(1405) in the flavor SU(3) limit using a separable potential in the HAL QCD method

    Kotaro Murakami🇯🇵 · Sinya Aoki🇯🇵

    Using the HAL QCD method, we investigate S-wave meson-baryon interactions in singlet and two octet channels in the flavor SU(3) limit, where the chiral unitary model predicts that a combination of bound-state poles in these channels corresponds to $\Lambda (1405)$. To avoid the singular behavior of the leading-order potentials of these channels in the derivative expansion, we instead employ a separable potential in the time-dependent HAL QCD method. To calculate all-to-all propagators in the three-point correlation functions including $\Lambda$-baryon source operators with zero momentum, we employ the conventional stochastic estimation combined with the covariant approximation averaging. Separable potentials both in the singlet and octet channels show attraction without singular behavior. Our results of the corresponding phase shifts indicate that the attractive interaction in the singlet channel is stronger than that in the octet. Binding energies are consistent with the estimates from the two-point correlation function within one (two) sigma for the singlet (octet) channel, and this ordering of binding energies is consistent with the mass hierarchy suggested by the chiral unitary model.

    ↳ hep-lathep-phnucl-thPoS(2025)·2 citations
20. 20*

    Resolving the critical bubble in SU(8) deconfinement transition

    Kari Rummukainen🇫🇮 · Riikka Seppä🇫🇮 · David J. Weir🇫🇮

    Strongly coupled confining models with a first order phase transition present an interesting DM candidate. Near the critical temperature these models are strongly non-perturbative, and the critical bubble nucleation rate has so far only been estimated via approximative methods. As a model of a strong first order deconfinement transition, we simulate 4D SU(8) pure gauge model with multicanonical Monte Carlo. We demonstrate that resolving the critical bubble is possible in a strongly coupled model. We calculate the free energy of a critical bubble, which gives a rough upper limit for the nucleation rate. For the parameter points we investigated, the thin-wall approximation for the critial bubble free energy is off by a factor of 2, overestimating the rate at least by a factor of $e^{10}$.

    ↳ hep-lathep-phPoS(2025)·8 citations
21. 21*

    Exploring the Effects of Mass Dependence in Spontaneous Collapse Models

    Nicolò Piccione · Angelo Bassi🇮🇹

    Spontaneous collapse models aim to solve the long-standing measurement problem in quantum mechanics by modifying the theory's dynamics to include objective wave function collapses. These collapses occur randomly in space, bridging the gap between quantum and classical behavior. A central feature of these models is their dependence on mass density, which directly influences how and when collapse events occur. In this work, we explore a generalized framework in which the collapse dynamics depend on arbitrary functions of the mass density, extending previous models. We analyze the theoretical consistency of these generalizations, investigate their predictions, and compare them with experimental data. Our findings show that only a limited range of mass-dependence functions are viable, with significant implications for the future development and empirical testability of collapse-based models. Importantly, they also indicate that a well-justified model denoted here as PSL shows much more resilience to experimental falsification than standard collapse models.

    ↳ quant-phhep-phPRA(2025)·7 citations
22. 22*

    The four-gluon vertex from lattice QCD

    Manuel Colaço🇵🇹 · Orlando Oliveira🇵🇹 · Paulo J. Silva🇵🇹

    The four-gluon one-particle irreducible Green function contributes to various quantities with phenomenological relevance. An example where the four-gluon plays a role is the determination of the gluon propagator, a basic building block for QCD, using continuum methods. This four leg Green function is poorly known and we are only starting to grasp its non-perturbative structure. Here, we report on the computation of the one-particle irreducible four-gluon Green function, in the Landau gauge, with lattice simulations. Besides stating the problems associated with the computation, several form factors that characterise this Green function are measured.

    ↳ hep-lathep-phPoS(2025)·1 citation
23. 23*

    Two-Step Procedure to Detect Cosmological Gravitational Wave Backgrounds with Next-Generation Terrestrial Gravitational-Wave Detectors

    Haowen Zhong🇺🇸 · Luca Reali🇺🇸 · Bei Zhou🇺🇸 · Emanuele Berti🇺🇸 · Vuk Mandic🇺🇸

    Cosmological gravitational-wave backgrounds are an exciting science target for next-generation ground-based detectors, as they encode invaluable information about the primordial Universe. However, any such background is expected to be obscured by the astrophysical foreground from compact-binary coalescences. We propose a novel framework to detect a cosmological gravitational-wave background in the presence of binary black holes and binary neutron star signals with next-generation ground-based detectors, including Cosmic Explorer and the Einstein Telescope. Our procedure involves first removing all the individually resolved binary black hole signals by notching them out in the time-frequency domain. Then, we perform joint Bayesian inference on the individually resolved binary neutron star signals, the unresolved binary neutron star foreground, and the cosmological background. For a flat cosmological background, we find that we can claim detection at $5\sigma$ level when ${\Omega }_{\mathrm{ref}}⩾2.7\times 10^{-12}/\sqrt{T_{\mathrm{obs}}/\mathrm{yr}}$, where $T_{\mathrm{obs}}$ is the observation time (in years), which is within a factor of $\lesssim 2$ from the sensitivity reached in absence of these astrophysical foregrounds.

    ↳ gr-qcastro-ph.COastro-ph.HEastro-ph.IM+1PRL(2025)·16 citations
24. 24*

    Single versus multifield scalar potentials from string theory

    David Andriot🇫🇷 · Muthusamy Rajaguru🇺🇸 · George Tringas🇺🇸

    In this work, we investigate the properties of string effective theories with scalar field(s) and a scalar potential. We first claim that in most examples known, such theories are multifield, with at least 2 non-compact field directions; the few counter-examples appear to be very specific and isolated. Such a systematic multifield situation has important implications for cosmology. Characterising properties of the scalar potential $V$ is also more delicate in a multifield setting. We provide several examples of string effective theories with $V>0$, where the latter admits an asymptotically flat direction along an off-shell field trajectory: in other words, there exists a limit $\phi \to \infty$ for which $\frac{|{\partial }_{\phi }V|}{V}\to 0$. It is thus meaningless to look for a lower bound to this single field quantity in a multifield setting; the complete gradient $\nabla V$ is then better suited. Restricting to on-shell trajectories, this question remains open, especially when following the steepest descent or more generally a gradient flow evolution. Interestingly, single field statements in multifield theories seem less problematic for $V<0$.

    ↳ hep-thastro-ph.COgr-qchep-ph+2JHEP(2025)·6 citations
25. 25*

    Inequivalence between the Euclidean and Lorentzian versions of the type IIB matrix model from Lefschetz thimble calculations

    Chien-Yu Chou🇯🇵 · Jun Nishimura🇯🇵 · Ashutosh Tripathi🇯🇵

    The type IIB matrix model is conjectured to describe superstring theory nonperturbatively in terms of ten $N\times N$ bosonic traceless Hermitian matrices $A_{\mu }$ ($\mu =0,\dots ,9$), whose eigenvalues correspond to $(9+1)$-dimensional space-time. Quite often, this model has been investigated in its Euclidean version, which is well defined although the $\mathrm{SO}(9,1)$ Lorentz symmetry of the original model is replaced by the $\mathrm{SO}(10)$ rotational symmetry. Recently, a well-defined model respecting the Lorentz symmetry has been proposed by gauge-fixing the Lorentz symmetry nonperturbatively using the Faddeev-Popov procedure. Here we investigate the two models by Monte Carlo simulations, overcoming the severe sign problem by the Lefschetz thimble method, in the case of matrix size $N=2$ omitting fermionic contributions. We add a quadratic term $\gamma \mathrm{tr}(A_{\mu }{A}^{\mu })$ in the action and calculate the expectation values of rotationally symmetric (or Lorentz symmetric) observables as a function of the coefficient $\gamma$. Our results exhibit striking differences between the two models around $\gamma =0$ and in the $\gamma >0$ region, associated with the appearance of different saddle points, clearly demonstrating their inequivalence against naive expectations from quantum field theory.

    ↳ hep-thgr-qchep-lathep-phPRL(2025)·20 citations
26. 26*

    Predicting the spectrum and decay constants of positive-parity heavy-strange mesons using domain-wall fermions

    Forrest Guyton🇺🇸 · Stefan Meinel🇺🇸

    We present a lattice-QCD calculation of the masses and decay constants of the positive-parity heavy-strange mesons $D_{s0}^{\ast }$, $D_{s1}$, $B_{s0}^{\ast }$, and $B_{s1}$. The calculations are performed with domain-wall fermions for the light and strange quarks and an anisotropic clover action for the charm and bottom quarks. We use seven different RBC/UKQCD ensembles with pion masses ranging from a near-physical 139 MeV up to 431 MeV. We consider two different analysis types, with or without two-meson operators at the source. We observe the expected below-threshold ground states. The fits without the two-meson operators appear to be more stable, but may overestimate the ground-state energies, while preliminary fits with two-meson operators at the source only appear to underestimate the ground-state energies.

    ↳ hep-lathep-phPoS(2025)·0 citations
27. 27*

    Zubarev response approach to polarization phenomena in local equilibrium

    Youyu Li🇨🇳 · Shuai Y. F. Liu🇨🇳

    Using the expansion of Zubarev's density operator, we develop a linear response approach to study various spin physics in a locally equilibrated medium, particularly focusing on various polarization phenomena in heavy-ion collisions. Specifically, we connect familiar correlation functions and diagrammatic methods to the Zubarev formalism, enabling the use of established techniques like the Matsubara/imaginary time formalism to facilitate calculations. For a spin-1/2 particle, we re-derive its vector polarization using this Zubarev response approach, which exactly reproduces with our previous results based on Luttinger's method. For a spin-1 particle, we calculate the vector polarization and find the expected contributions from vorticity, temperature gradients, and shear, which are identical to those for spin-1/2 particles except for a factor of 4/3 as expected. For the tensor polarization and spin alignment of a spin-1 boson, we explicitly prove that the non-dissipative contribution is zero at leading order in gradients, and briefly reiterate our previous findings for the dissipative contribution with further discussions on several concerns. Additionally, we discuss several relevant subtleties and questions, including an alternative derivation for Zubarev response approach, the covariance issues of different spin density matrix definitions, a further explanation of slow and fast modes, the mode selection scheme, etc. We also discuss skeleton expansions, higher-order contributions, and non-perturbative methods, particularly their potential connection to lattice field theory. In summary, this work discusses the foundations and subtleties of Zubarev response approach, with specific examples from spin physics in heavy-ion collisions.

    ↳ nucl-thhep-phhep-thnucl-exPRC(2026)·12 citations
28. 28*

    Coulomb interacting Bose-Einstein correlations in Fourier space

    Aletta Purzsa🇭🇺

    In high-energy heavy-ion physics experiments, a state of matter is created that existed in the early Universe: the quark-gluon plasma. This strongly interacting matter exists in today's experiments only within a range of a few femtometers and for a duration of a few femtometers per speed of light, making its resolution with optical tools impossible. However, there is a method that allows for a closer look into the structure of the quark-gluon plasma: femtoscopy. Initially used in astronomy, femtoscopy is based on the quantum mechanical indistinguishability of identical particles, which causes them to arrive at detectors in a correlated manner. The measurable correlation is related to the spacetime structure of the particle-emitting source, which in heavy-ion physics is the quark-gluon plasma created in collisions. For free particles, a relatively simple relationship exists between the source and the correlation (essentially a Fourier transform). However, this relationship becomes complex when accurately accounting for the repulsive Coulomb interaction between final-state electrically charged particles. Our paper presents a new method that is more precise than previously used ones, yet less computationally demanding, especially for the exotic source function shapes. Mathematically, the method is interesting because it exactly handles many emerging integrals and limits. Practically, it is ready for use in experimental analyses.

    ↳ nucl-thhep-phhep-thInt.J.Mod.Phys.A(2025)·0 citations
29. 29*

    Aspects of Spatially-Correlated Random Fields: Extreme-Value Statistics and Clustering Properties

    Ka Hei Choi · James Creswell · Florian Kuhnel🇩🇪 · Dominik J. Schwarz

    Rare events of large-scale spatially-correlated exponential random fields are studied. The influence of spatial correlations on clustering and non-sphericity is investigated. The size of the performed simulations permits to study beyond-$7.5$-sigma events (one in $10^{13}$). As an application, this allows to resolve individual Hubble patches which fulfil the condition for primordial black hole formation. It is argued that their mass spectrum is drastically altered due to co-collapse of clustered overdensities as well as the mutual threshold-lowering through the latter. Furthermore, the corresponding non-sphericities may imply possibly large changes in the initial black hole spin distribution.

    ↳ astro-ph.COgr-qchep-phphysics.data-anPRD(2026)·4 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.