Thu·Apr 4, 2024Thursday·April 4, 2024

1. 01*

   A Scotogenic Model as a Prototype for Leptogenesis with One Single Gauge Singlet

   Björn Garbrecht🇩🇪 · Edward Wang🇩🇪

   We investigate the potential of a minimal Scotogenic model with two additional scalar doublets and a single heavy Majorana fermion to explain neutrino masses, dark matter, and the baryon asymmetry of the Universe. In this minimal setup, Leptogenesis is purely flavored, and a second Majorana neutrino is not necessary because the Yukawa couplings of the extra doublets yield the necessary $CP$-odd phases. The mechanism we employ can also be applied to a wide range of scenarios with at least one singlet and two gauge multiplets. Despite stringent limits from the dark matter abundance, direct detection experiments, and the baryon asymmetry of the Universe, we find a parametric region consistent with all bounds which could resolve the above shortcomings of the Standard Model of particle physics. Methodically, we improve on the calculation of correlations between the mixing scalar fields given their finite width. We also present an argument to justify the kinetic equilibrium approximation for out-of-equilibrium distribution functions often used in calculations of Baryogenesis and Leptogenesis.

   hep-phastro-ph.COhep-thPRD(2024)·4 citations
2. 02*

   Avenues for a number density interpretation of dihadron fragmentation functions

   T. Rogers🇺🇸 · A. Courtoy🇲🇽

   In this comment, we reassess the underlying physics of the number sum rule for dihadron fragmentation functions. We will argue that, currently, there are no settled constraints on what constitutes a valid number density interpretation for multihadron fragmentation functions. Imposing overly restrictive criteria might lead to misinterpretating the data. Most importantly, and on the basis of phenomenological analyses, the slightly varying definitions used in previous work are not excluded from possessing legitimate number density interpretations (up to the usual issues with ultraviolet divergences and renormalization), so long as they are paired with appropriate factorization theorems. We advocate for further theoretical analyses to be challenged with experimental data, available at JLab or at the future EIC.

   hep-phnucl-exnucl-thRev.Mex.Fis.(2025)·2 citations
3. 03*

   Muon g-2 and lepton flavor violation in supersymmetric GUTs

   Mario E. Gomez🇪🇸 · Smaragda Lola🇬🇷 · Qaisar Shafi🇺🇸 · Cem Salih Un🇹🇷

   We present a class of supersymmetric (SUSY) GUT models that can explain the apparent discrepancy between the SM predictions and experimental values of muon g-2 while providing testable signals for lepton flavor violation in charged lepton decays. Moreover, these models predict LSP neutralino abundance that is compatible with the Planck dark matter bounds. We find that scenarios in the framework of $SU(4{)}_c\times SU(2{)}_L\times SU(2{)}_R$ unification, with additional symmetries to explain fermion masses and neutrino oscillations, provide interesting benchmarks for the search of SUSY by correlating a possible manifestation of it in dark matter, rare lepton decays and LHC signals.

   hep-phPRD(2024)·5 citations
4. 04*

   Net proton number cumulants from viscous hydro with equation of state including a critical end point

   Yi-fan Shen🇨🇳 · Wei Chen🇨🇳 · Xiang-yu Wu🇨🇦 · Kun Xu🇨🇳 · Mei Huang🇨🇳

   In the SMASH-CLVisc-hybrid framework, including SMASH for the initial conditions and the hadronic rescattering stage, and CLVisc for the quark gluon plasma (QGP) evolution, we investigate net baryon number fluctuations via considering the equation of state (EoS) with and without a critical end point (CEP) in the QCD phase transition. Specifically, two distinct QCD EoS are utilized: one with smooth crossover derived from NEOS and another with a critical end point sourced from the rPNJL model. Our results show that non-monotonic behavior of $\kappa {\sigma }^2$ is not observed above the collision energy $7.7\mathrm{GeV}$, nor are there explicit differences between the EoS characterized by crossover and that by CEP. This could be attributed to the significant deviation of the freeze-out line from the location of CEP. It is also found that the pure SMASH result of $\kappa {\sigma }^2$ is positive and close to zero at 3 GeV, which is different from the negative value observed from STAR.

   hep-phnucl-thPRC(2025)·3 citations
5. 05*

   One-loop contributions for $A^0\to \ell \bar{\ell }V$ with $\ell \equiv e,\mu$ and $V\equiv \gamma ,Z$ in Higgs Extensions of the Standard Model

   Khiem Hong Phan (DTU)🇩🇰 · Dzung Tri Tran (DTU)🇩🇰 · Thanh Huy Nguyen (HCMUS)🇻🇳

   We present one-loop formulas for the decay of CP-odd Higgs $A^0\to \ell \bar{\ell }V$ with $\ell \equiv e,\mu$ and $V\equiv \gamma ,Z$ in Higgs Extensions of the Standard Model, considering two higgs doublet model with a complex (and real) scalar, two higgs doublet model as well as triplet higgs model. Analytic results for one-loop amplitudes are expressed in terms of Passarino-Veltman functions following the standard notations of {\tt LoopTools}. As a result, physical results can be generated numerically by using the package. In phenomenological results, the total decay widths and the differential decay rates with respect to the invariant mass of lepton pair are analyzed for two typical models such as two higgs doublet model and triplet higgs model.

   hep-phPTEP(2024)·5 citations
6. 06*

   Automatic generation of orthogonal multiplet bases in $\mathrm{SU}(N_c)$ color space

   Bakar Chargeishvili🇩🇪

   We present a software that automatically generates a multiplet color basis for general $2\to n$ processes in quantum chromodynamics (QCD). The construction process is guided by the decomposition of the corresponding $\mathrm{SU}(N_c)$ representation into a direct sum of irreducible representations. The projectors of these irreducible multiplet states are then used to construct a minimal, linearly independent basis. The software achieves highest efficiency through a combination of the Z3 satisfiability modulo theories solver and the symbolic manipulation program FORM. The resulting color basis enables the analytical execution of involved QCD calculations that require color decomposition.

   hep-ph2 citations
7. 07*

   Deep learning for flow observables in high energy heavy-ion collisions

   H. Hirvonen🇫🇮 · K.J. Eskola🇫🇮 · H. Niemi🇫🇮

   We demonstrate how deep convolutional neural networks can be trained to predict 2+1 D hydrodynamic simulation results for flow coefficients, mean-transverse-momentum and charged particle multiplicity from the initial energy density profile. We show that this method provides results that are accurate enough, so that one can use neural networks to reliably estimate multi-particle flow correlators. Additionally, we train networks that can take any model parameter as an additional input and demonstrate with a few examples that the accuracy remains good. The usage of neural networks can reduce the computation time needed in performing Bayesian analyses with multi-particle flow correlators by many orders of magnitude.

   hep-phnucl-thEPJ Web Conf.(2024)·3 citations
8. 08*

   Chiral symmetry restoration at finite temperature in a model with manifest confinement

   L. Ya. Glozman🇦🇹 · A. V. Nefediev🇸🇮 · R. Wagenbrunn🇦🇹

   Multiple lattice evidences support the existence of a confining but chirally symmetric regime of QCD above the chiral symmetry restoration crossover at Tch ~ 155 MeV. This regime is characterised by an approximate chiral spin symmetry of the partition function, which is a symmetry of the colour charge and the confining electric part of the QCD Lagrangian. It is traditionally believed that confinement should automatically induce spontaneous breaking of chiral symmetry, which would preclude the existence of a confining but chirally symmetric regime of QCD at high temperatures. We employ a well-known solvable quark model for QCD in 3+1 dimensions that is chirally symmetric and manifestly confining and argue that while confinement indeed induces dynamical breaking of chiral symmetry at T=0, a chiral restoration phase transition takes place at some critical temperature Tch. Above this temperature, the spectrum of the model consists of chirally symmetric hadrons with approximate chiral spin symmetry.

   hep-phhep-lathep-thnucl-thPLB(2024)·13 citations
9. 09*

   Sibyll${}^{★}$

   Felix Riehn🇪🇸 · Anatoli Fedynitch🇹🇼 · Ralph Engel🇩🇪

   In the last decade, an increasing number of datasets have revealed a consistent discrepancy between the number of muons measured in ultra-high-energy extensive air showers (EAS) and the numbers predicted by simulations. This gap persists despite incorporating Large Hadron Collider (LHC) data into the tuning of current hadronic interaction models, leading to the phenomenon often termed the ''muon puzzle''. To gain a deeper understanding of the potential origins of this muon puzzle, we have developed Sibyll${}^{★}$, a series of phenomenologically modified versions of Sibyll 2.3d. In these models, we have increased muon production by altering ${\rho }^0$, baryon-antibaryon pair, or kaon production in hadronic multiparticle production processes. These variants remain within bounds from provided by accelerator measurements, including those from the LHC and fixed-target experiments, notably NA49 and NA61, showing a level of consistency comparable to Sibyll 2.3d. Our findings show that these modifications can increase the muon count in EAS by up to 35%, while minimally affecting the depth of shower maximum ($X_{\max }$) and other shower variables. Additionally, we assess the impact of these modifications on various observables, including inclusive muon and neutrino fluxes and the multiplicities of muon bundles in deep underground and water/ice Cherenkov detectors. We aim for at least one of these model variants to offer a more accurate representation of EAS data at the highest energies, thereby enhancing the quality of Monte Carlo predictions used in training neural networks. This improvement is crucial for achieving more reliable data analyses and interpretations.

   hep-phastro-ph.HEAstropart.Phys.(2024)·25 citations
10. 10*

    Probing intractable beyond-standard-model parameter spaces armed with Machine Learning

    Rajneil Baruah🇮🇳 · Subhadeep Mondal🇮🇳 · Sunando Kumar Patra🇮🇳 · Satyajit Roy🇮🇳

    This article attempts to summarize the effort by the particle physics community in addressing the tedious work of determining the parameter spaces of beyond-the-standard-model (BSM) scenarios, allowed by data. These spaces, typically associated with a large number of dimensions, especially in the presence of nuisance parameters, suffer from the curse of dimensionality and thus render naive sampling of any kind -- even the computationally inexpensive ones -- ineffective. Over the years, various new sampling (from variations of Markov Chain Monte Carlo (MCMC) to dynamic nested sampling) and machine learning (ML) algorithms have been adopted by the community to alleviate this issue. If not all, we discuss potentially the most important among them and the significance of their results, in detail.

    hep-phEur.Phys.J.ST(2024)·12 citations
11. 11*

    Light-quark mass dependence of the $\Lambda (1405)$ resonance

    Xiu-Lei Ren🇩🇪

    We present the light-quark mass dependence of the $\Lambda (1405)$ resonance at leading order in a renormalizable framework of covariant chiral effective field theory. The meson-baryon scattering amplitudes, which are obtained by solving the scattering equation within time-ordered perturbation theory, follow the quark mass trajectory of the Coordinated Lattice Simulations consortium. At $M_{\pi }\approx 200$ MeV and $M_K\approx 487$ MeV, our parameter-free prediction of $\Lambda (1405)$ poles is consistent with the recent lattice results of BaSc Collaboration [Phys. Rev. Lett. 132, 051901 (2024)]. Varying the pion mass from $135$ MeV to $400$ MeV, we present the evolution of double-pole positions of $\Lambda (1405)$: the higher pole remains a resonance around the $\bar{K}N$ threshold; whereas the lower pole undergoes a transition from resonance to a virtual state, and ultimately to a bound state of the $\pi \Sigma$ system, which could be verified by the forthcoming lattice QCD simulations.

    hep-phnucl-thPLB(2024)·11 citations
12. 12*

    Probing the spatial distribution of gluons within the proton in the coherent vector meson production at large $|t|$

    Victor P. Goncalves🇧🇷 · Bruno D. Moreira🇧🇷 · Luana Santana🇧🇷

    The coherent production of vector mesons in photon - hadron interactions is considered one of the most promising observables to probe the QCD dynamics at high energies and the transverse spatial distribution of the gluons in the hadron wave function. In this paper, we perform an exploratory study about the dependence of the transverse momentum distributions, $d\sigma /dt$, on the model assumed for the proton density profile. We consider a set of non-Gaussian profiles and include them in the forward dipole - proton scattering amplitude associated with the IP-sat model. We demonstrate that the predictions for $d\sigma /dt$ are similar in the HERA kinematical range, but are very distinct for values of $t$ that will be probed in future colliders. In particular, the presence of diffractive dips in the $t$-distributions associated with the production of $J/\Psi$ and $\rho$ mesons is strongly dependent on the model assumed for the density profile. Similar conclusions are also derived when the non-linear effects on the dipole - target interaction are disregarded. Our results indicate that a future study of the coherent vector meson production at large - $t$ will be useful to constrain the spatial distribution of gluons within the proton.

    hep-phhep-exEPJC(2024)·6 citations
13. 13*

    A plethora of long-range neutrino interactions probed by DUNE and T2HK

    Sanjib Kumar Agarwalla🇮🇳 · Mauricio Bustamante🇩🇰 · Masoom Singh🇮🇳 · Pragyanprasu Swain🇮🇳

    Upcoming neutrino experiments will soon search for new neutrino interactions more thoroughly than ever before, boosting the prospects of extending the Standard Model. In anticipation of this, we forecast the capability of two of the leading long-baseline neutrino oscillation experiments, DUNE and T2HK, to look for new flavor-dependent neutrino interactions with electrons, protons, and neutrons that could affect the transitions between different flavors. We interpret their sensitivity in the context of long-range neutrino interactions, mediated by a new neutral boson lighter than $10^{-10}$ eV, and sourced by the vast amount of nearby and distant matter in the Earth, Moon, Sun, Milky Way, and beyond. For the first time, we explore the sensitivity of DUNE and T2HK to a wide variety of $U(1{)}^{\prime }$ symmetries, built from combinations of lepton and baryon numbers, each of which induces new interactions that affect oscillations differently. We find ample sensitivity: in all cases, DUNE and T2HK may constrain the existence of the new interaction even if it is supremely feeble, may discover it, and, in some cases, may identify the symmetry responsible for it.

    hep-phastro-ph.HEhep-exhep-thJHEP(2024)·13 citations
14. 14*

    Pre-equilibrium Photon and Dilepton Production

    Oscar Garcia-Montero🇩🇪 · Aleksas Mazeliauskas🇩🇪 · Philip Plaschke🇩🇪 · Sören Schlichting🇩🇪

    We use QCD kinetic theory to compute photon and dilepton production in the chemically equilibrating out-of-equilibrium quark-gluon plasma created in the early stages of high-energy heavy-ion collisions. We derive universal scaling functions for the pre-equilibrium spectra of photons and dileptons. These scaling functions can be used to make realistic predictions for the pre-equilibrium emission and consequently establish the significance of the pre-equilibrium phase for the production of electromagnetic probes in heavy-ion collisions.

    hep-phnucl-thEPJ Web Conf.(2024)·3 citations
15. 15*

    Pair production in rotating electric fields via quantum kinetic equations: Resolving helicity states

    I. A. Aleksandrov🇷🇺 · A. Kudlis🇮🇸

    We investigate the phenomenon of electron-positron pair production from vacuum in the presence of a strong electric field of circular polarization. By means of a nonperturbative approach based on the quantum kinetic equations (QKEs), we numerically calculate helicity-resolved momentum distributions of the particles produced and analyze the corresponding helicity asymmetry. It is demonstrated that the external rotating field tends to generate left-handed and right-handed particles traveling in opposite directions. Generic symmetry properties of the momentum spectra are examined analytically by means of the QKEs and also confirmed and illustrated by direct numerical computations. The helicity signatures revealed in our study are expected to provide a firmer basis for possible experimental investigations of the fundamental phenomenon of vacuum pair production in strong fields.

    hep-phPRD(2024)·16 citations
16. 16*

    Hitting the Thermal Target for Leptophilic Dark Matter

    Cari Cesarotti🇺🇸 · Gordan Krnjaic🇺🇸

    We study future lepton collider prospects for testing predictive models of leptophilic dark matter candidates with a thermal origin. We calculate experimental milestones for testing the parameter space compatible with freeze-out and the associated collider signals at past, present, and future facilities. This analysis places new limits on such models by leveraging the utility of lepton colliders. At $e^{+}{e}^{-}$ machines, we make projections using precision $Z$-pole observables from $e^{+}{e}^{-}\to l^{+}{l}^{-}+$ missing energy signatures at LEP and future projections for FCC-ee in these channels. Additionally, a muon collider could also probe new thermal relic parameter space in this scenario via ${\mu }^{+}{\mu }^{-}\to X+$ missing energy where $X$ is any easy identifiable SM object. Collectively, these processes can probe much all of the parameter space for which DM direct annihilation to $l^{+}{l}^{-}$ yields the observed relic density in Higgs-like models with mass-proportional couplings to charged leptons.

    hep-phPRL(2025)·12 citations
17. 17*

    Sledgehamr: Simulating Scalar Fields with Adaptive Mesh Refinement

    Malte Buschmann🇳🇱

    Understanding the nonlinear dynamics of coupled scalar fields often necessitates simulations on a 3D mesh. These simulations can be computationally expensive if a large scale separation is involved. A common solution is adaptive mesh refinement which, however, greatly increases a simulation's complexity. In this work, we present sledgehamr, an AMReX-based code package to make the simulation of coupled scalar fields on an adaptive mesh more accessible. Compatible with both GPU and CPU clusters, sledgehamr offers a flexible and customizable framework. While the code had been primarily developed to evolve axion string networks, this framework enables various other applications, such as the study of gravitational waves sourced by the dynamics of scalar fields.

    hep-phastro-ph.COgr-qcApJ(2025)·13 citations
18. 18*

    Multi-messenger Probes of Asteroid Mass Primordial Black Holes: Superradiance Spectroscopy, Hawking Radiation, and Microlensing

    James B. Dent🇺🇸 · Bhaskar Dutta🇺🇸 · Tao Xu🇺🇸

    Superradiance provides a unique opportunity for investigating dark sectors as well as primordial black holes, which themselves are candidates for dark matter over a wide mass range. Using axion-like particles as an example, we show that line signals emerging from a superradiated axion cloud combined with black hole Hawking radiation in extragalactic and galactic halos, along with microlensing observations lead to complementary constraints on parameter space combinations including the axion-photon coupling, axion mass, black hole mass, and its dark matter fraction, $f_{\mathrm{PBH}}$. For the asteroid mass range $\sim 10^{16}-10^{22}\mathrm{g}$, where primordial black holes can provide the totality of dark matter, we demonstrate that ongoing and upcoming observations such as SXI, JWST, and AMEGO-X will be sensitive to possible line and continuum signals, respectively, providing probes of previously inaccessible regions of $f_{\mathrm{PBH}}$ parameter space. Further complementarity from a stochastic gravitational-wave background emerging from the black hole formation mechanism is also considered.

    hep-phastro-ph.COPLB(2025)·24 citations
19. 19*

    A first determination of the strong coupling ${\alpha }_S$ at approximate N${}^3$LO order in a global PDF fit

    T. Cridge🇩🇪 · L.A. Harland-Lang🇬🇧 · R.S. Thorne🇬🇧

    We present the first determination of the value of the strong coupling via a simultaneous global fit of the proton parton distribution functions (PDFs) at approximate N${}^3$LO (aN${}^3$LO) order in QCD. This makes use of the MSHT global PDF fitting framework, and in particular the recent theoretical advances that allow a PDF fit to now be performed at this order. The value of the strong coupling is found to be ${\alpha }_S(M_Z^2)$(aN${}^3$LO)$=0.1170\pm 0.0016$. This is in excellent agreement with the NNLO value of ${\alpha }_S(M_Z^2)$(NNLO) $=0.1171\pm 0.0014$, indicating that good perturbative convergence has been found. The resulting uncertainties, calculated using the MSHT dynamic tolerance procedure, are somewhat larger, but more accurate, at aN${}^3$LO, due to the missing higher order theoretical uncertainties that are included at this order, but not at NNLO. We in addition present a detailed breakdown of the individual dataset sensitivity to the value of the strong coupling, with special focus on the impact of fitting dijet rather than inclusive jet data. This choice is found to have a non-negligible impact, but with overall good consistency found, especially at aN${}^3$LO.

    hep-phEPJC(2024)·23 citations
20. 20*

    Re-assessing special aspects of Dirac fermions in presence of Lorentz-symmetry violation

    João Paulo S. Melo🇧🇷 · José A. Helayël-Neto🇧🇷

    This paper focuses on additional inspections concerning the fermionic sector of the Standard Model Extension (SME). In this context, our main effort in this contribution is to investigate effects of Lorentz-symmetry violation (LSV) on the Klein Paradox, the Zitterbewegung and its phenomenology in connection to Condensed Matter Physics, Atomic Physics, and Astrophysics. Finally, we discuss a particular realization of LSV in the Dirac equation, considering an asymmetry between space and time due to a scale factor present in the linear momentum of the fermion, but which does not touch its time derivative. We go further and extend the implications of this asymmetry in the situation the scale factor becomes space-time dependent to compute its influence on the kinematics of the Compton effect with the extended dispersion relation for the fermion that scatters the photon.

    hep-phhep-thAnnals Phys.(2024)·7 citations
21. 21*

    Kaon mixing beyond the standard model with physical masses

    Peter A. Boyle🇺🇸 · Felix Erben🇨🇭 · Jonathan M. Flynn🇬🇧 · Nicolas Garron🇬🇧 · Julia Kettle🇬🇧 · Rajnandini Mukherjee🇬🇧 · J. Tobias Tsang🇨🇭

    We present non-perturbative results for beyond the standard model kaon mixing matrix elements in the isospin symmetric limit ($m_u=m_d$) of QCD, including a complete estimate of all dominant sources of systematic error. Our results are obtained from numerical simulations of lattice QCD with $N_f=2+1$ flavours of dynamical domain wall fermions. For the first time, these quantities are simulated directly at the physical pion mass $m_{\pi }$~$\sim$~$139\mathrm{MeV}$ for two different lattice spacings. We include data at three lattice spacings in the range $a=0.11$ - $0.07\mathrm{fm}$ and with pion masses ranging from the physical value up to 450$\mathrm{MeV}$. Compared to our earlier work, we have added both direct calculations at physical quark masses and a third lattice spacing making the removal of discretisation effects significantly more precise and eliminating the need for any significant mass extrapolation beyond the range of simulated data. We renormalise the lattice operators non-perturbatively using RI-SMOM off-shell schemes. These schemes eliminate the need to model and subtract non-perturbative pion poles that arises in the RI-MOM scheme and, since the calculations are performed with domain wall fermions, the unphysical mixing between chirality sectors is suppressed. Our results for the bag parameters in the $\overline{\mathrm{MS}}$ scheme at $3\mathrm{GeV}$ are $B_K\equiv {\mathcal{B}}_1=0.5240(17)(54)$, ${\mathcal{B}}_2=0.4794(25)(35)$, ${\mathcal{B}}_3=0.746(13)(17)$, ${\mathcal{B}}_4=0.897(02)(10)$ and ${\mathcal{B}}_5=0.6882(78)(94)$, where the first error is from lattice uncertainties and the second is the uncertainty due to the perturbative matching to $\overline{\mathrm{MS}}$.

    ↳ hep-lathep-phPRD(2024)·21 citations
22. 22*

    Replica Wormholes and Quantum Hair

    Xavier Calmet🇬🇧 · Stephen D.H. Hsu🇺🇸

    We discuss recent applications of Euclidean path integrals to the black hole information problem. In calculations with replica wormholes as the next-to-leading order correction to the Gibbons-Hawking saddlepoint, the radiation density matrix approaches a pure state at late times, following the Page curve. We compare unitary evaporation of black holes (in real time), mediated by calculable quantum hair effects, with the replica wormhole results. Both replica wormhole and quantum hair approaches imply that radiation states are macroscopic superpositions of spacetime backgrounds, invalidating firewall and monogamy of entanglement constructions. Importantly, identification of modes inside the horizon with radiation modes (i.e., large scale nonlocality across the horizon) is not required to provide a physical picture of unitary evaporation. Radiation modes can encode the interior information while still remaining independent degrees of freedom.

    ↳ hep-thhep-phFortsch.Phys.(2026)·7 citations
23. 23*

    Thermodynamic formulation of vacuum energy density in flat spacetime and potential implications for the cosmological constant

    André LeClair🇺🇸

    We propose a thermodynamical definition of the vacuum energy density ${\rho }_{\mathrm{vac}}$, defined as $⟨0|T_{\mu \nu }|0⟩=-{\rho }_{\mathrm{vac}}{g}_{\mu \nu }$, in quantum field theory in flat Minkowski space in $D$ spacetime dimensions, which can be computed in the limit of high temperature, namely in the limit $\beta =1/T\to 0$. It takes the form ${\rho }_{\mathrm{vac}}=\mathrm{const}\cdot m^D$ where $m$ is a fundamental mass scale and $"const"$ is a computable constant which can be positive or negative. Due to modular invariance ${\rho }_{\mathrm{vac}}$ can also be computed in a different non-thermodynamic channel where one spatial dimension is compactifed on a circle of circumference $\beta$ and we confirm this modularity for free massive theories for both bosons and fermions for $D=2,3,4$. We list various properties of ${\rho }_{\mathrm{vac}}$ that are generally required, for instance ${\rho }_{\mathrm{vac}}=0$ for conformal field theories, and others, such as the constraint that ${\rho }_{\mathrm{vac}}$ has opposite signs for free bosons verses fermions of the same mass, which is related to constraints from supersymmetry. Using the Thermodynamic Bethe Ansatz we compute ${\rho }_{\mathrm{vac}}$ exactly for 2 classes of integrable QFT's in $2D$ and interpreting some previously known results. We apply our definition of ${\rho }_{\mathrm{vac}}$ to Lattice QCD data with two light quarks (up and down) and one additional massive flavor (the strange quark), and find it is negative, ${\rho }_{\mathrm{vac}}\approx -(200\mathrm{MeV}{)}^4$. Finally we make some remarks on the Cosmological Constant Problem since ${\rho }_{\mathrm{vac}}$ is central to any discussion of it.

    ↳ hep-thhep-lathep-phmath-ph+1JHEP(2024)·2 citations
24. 24*

    Enhanced Curvature Perturbation and Primordial Black Hole Formation in Two-stage Inflation with a break

    Xinpeng Wang🇨🇳 · Ying-li Zhang🇨🇳 · Misao Sasaki🇯🇵

    We investigate a model of $R^2$-gravity with a non-minimally coupled scalar field that gives rise to two-stage inflation with a break, that is, with an intermediate stage where inflation momentarily halts. We find that the power spectrum of the primordial curvature perturbation is significantly enhanced at the break scale, which can account for the primordial black hole (PBH) formation, without affecting the CMB constraint on large scales. The behavior of the curvature perturbation is carefully analyzed and we find a few notable new features in the spectrum. In particular, we find that the $k^3$ growth of the spectrum of toward the end of the first stage of inflation. We argue that this is a universal feature common to all two-stage models where the field dominating the second stage is heavy during the first stage. By appropriately tuning the model parameters, we find that our model can realize the scenario of PBHs as the cold dark matter of the Universe. We also find that we can choose the parameters so that the spectrum of the induced gravitational waves from the enhanced curvature perturbation fits the NANOGrav-15yr data of pulsar timing array observation.

    ↳ astro-ph.COgr-qchep-phJCAP(2024)·54 citations
25. 25*

    Searches for multi-Z boson productions and anomalous gauge boson couplings at a muon collider

    Ruobing Jiang🇨🇳 · Chuqiao Jiang🇨🇳 · Alim Ruzi🇨🇳 · Tianyi Yang🇨🇳 · Yong Ban🇨🇳 · Qiang Li🇨🇳

    Multi-boson productions can be exploited as novel probes either for standard model precision tests or new physics searches, and have become one of those popular topics in the ongoing LHC experiments, and in future collider studies, including those for electron-positron and muon-muon colliders. Here we focus on two examples, i.e., ZZZ direct productions through ${\mu }^{+}{\mu }^{-}$ annihilation at a 1 TeV muon collider, and ZZ productions through vector boson scattering at a 10 TeV muon collider, with an integrated luminosity of $10{\text{ab}}^{-1}$. Various channels are considered, including, such as $ZZZ\to 4l2\nu$ and $ZZZ\to 4l+2\text{ jets}$, etc. Expected significance on these multi-Z boson production processes are provided based on a detailed Monte Carlo study and signal background analysis. Sensitives on anomalous gauge boson couplings are also presented.

    ↳ hep-exhep-phCPC(2024)·5 citations
26. 26*

    Softening of the Hypertriton Transverse Momentum Spectrum in Heavy-Ion Collisions

    Dai-Neng Liu🇨🇳 · Che Ming Ko🇺🇸 · Yu-Gang Ma🇨🇳 · Francesco Mazzaschi🇮🇹 · Maximiliano Puccio🇨🇭 · Qi-Ye Shou🇨🇳 · Kai-Jia Sun🇨🇳 · Yuan-Zhe Wang🇨🇳

    Understanding the properties of hypernuclei helps to constrain the interaction between hyperon and nucleon, which is known to play an essential role in determining the properties of neutron stars. Experimental measurements have suggested that the hypertriton (${}_{\Lambda }^3\text{H}$), the lightest hypernucleus, exhibits a halo structure with a deuteron core encircled by a $\Lambda$ hyperon at a distance of about 10 fm. This large $\Lambda -d$ distance in ${}_{\Lambda }^3\text{H}$ wave function is found to cause a suppressed ${}_{\Lambda }^3\text{H}$ yield and a softening of its transverse momentum ($p_T$) spectrum in relativistic heavy-ion collisions. Within the coalescence model based on nucleons and $\Lambda$ hyperons from a microscopic hybrid hydro model with a hadronic afterburner for nuclear cluster production in Pb-Pb collisions at $\sqrt{s_{NN}}$= 5.02 TeV, we show how this softening of the hypertriton $p_T$ spectrum appears and leads to a smaller mean $p_T$ for ${}_{\Lambda }^3\text{H}$ than for helium-3 (${}^3$He). The latter is opposite to the predictions from the blast-wave model which assumes that ${}_{\Lambda }^3\text{H}$ and ${}^3$He are thermally produced at the kinetic freeze-out of heavy-ion collisions. The discovered quantum mechanical softening of the (anti-)hypertriton spectrum can be experimentally tested in relativistic heavy-ion collisions at different collision energies and centralities and used to obtain valuable insights into the mechanisms for light (hyper-)nuclei production in these collisions.

    ↳ nucl-thhep-phPLB(2024)·23 citations
27. 27*

    Revised bounds on local cosmic strings from NANOGrav observations

    Jun'ya Kume🇮🇹 · Mark Hindmarsh🇫🇮

    In a recent paper, the NANOGrav collaboration studied new physics explanations of the observed pulsar timing residuals consistent with a stochastic gravitational wave background (SGWB), including cosmic strings in the Nambu-Goto (NG) approximation. Analysing one of current models for the loop distribution, it was found that the cosmic string model is disfavored compared to other sources, for example, super massive black hole binaries (SMBHBs). When both SMBHB and cosmic string models are included in the analysis, an upper bound on a string tension $G\mu \lesssim 10^{-10}$ was derived. However, the analysis did not accommodate results from cosmic string simulations in an underlying field theory, which indicate that at most a small fraction of string loops survive long enough to emit GW. Following and extending our previous study, we suppose that a fraction $f_{\mathrm{NG}}$ of string loops follow NG dynamics and emit only GWs, and study the three different models of the loop distribution discussed in the LIGO-Virgo-KAGRA (LVK) collaboration analyses. We re-analyze the NANOGrav 15yrs data with our signal models by using the NANOGrav $\text{ENTERPRISE}$ analysis code via the wrapper $\text{PTArcade}$. We find that loop distributions similar to LVK Model B and C yield higher Bayes factor than Model A analyzed in the NANOGrav paper, as they can more easily accommodate a blue-tilted spectrum of the observed amplitude. Furthermore, because of the degeneracy of $G\mu$ and $f_{\mathrm{NG}}$ in determining the signal amplitude, our posterior distribution extends to higher values of $G\mu$, and in some cases the uppermost value of credible intervals is close to the Cosmic Microwave Background limit $G\mu \lesssim 10^{-7}$. Hence, in addition to the pulsar timing array data, further information about the fraction of long-lived loops in a cosmic string network is required to constrain the string tension.

    ↳ astro-ph.COgr-qchep-phJCAP(2024)·35 citations
28. 28*

    Renormalization of Scalar and Fermion Interacting Field Theory for Arbitrary Loop: Heat-Kernel Approach

    Upalaparna Banerjee🇮🇳 · Joydeep Chakrabortty🇮🇳 · Kaanapuli Ramkumar🇮🇳

    We outline a proposal, based on the Heat-Kernel method, to compute 1PI effective action up to any loop order for quantum field theory with scalar and fermion fields. We algebraically extract the divergences associated with the composite operators without explicitly performing any momentum loop integral. We perform this analysis explicitly for one and two-loop cases and pave the way for three-loop as well. Using our prescription we compute the two-loop counter terms for a theory containing higher mass dimensional effective operators that are polynomial in fields for two different cases: (i) real singlet scalar, and (ii) complex fermion-scalar interacting theories. We also discuss how the minimal Heat-Kernel fails to deal with the effective operators involving derivatives. We explicitly compute the one-loop counter terms for such a case within an $O(n)$ symmetric scalar theory employing a non-minimal Heat-Kernel. Our method computes the counter terms of the composite operators directly and is also useful for extracting infrared divergence in massless limits.

    ↳ hep-thhep-exhep-phEur.Phys.J.Plus(2024)·9 citations
29. 29*

    Precise Omega baryons from lattice QCD

    Renwick J. Hudspith🇩🇪 · Matthias F.M. Lutz🇩🇪 · Daniel Mohler🇩🇪

    In this paper we determine the masses of $I(J^P)=0\left(3/2^{+}\right)$ and $0\left(3/2^{-}\right)$ $\Omega$-baryon ground states using lattice QCD. We utilise Wilson-clover ensembles with $2+1$ dynamical quark flavours generated by the CLS consortium along a trajectory with a constant trace of the quark-mass matrix. We show that N${}^3$LO $\text{SU}(3{)}_f$ chiral perturbation theory expressions describe the ground-state masses with positive-parity well, and we use them to set the lattice scale. Methodologically, our combination of gauge-fixed wall sources and the generalized Pencil of Functions allows for high-precision determinations of the lattice spacing at a relative error of around $0.3\%$ with controlled excited-state contamination. The fit we perform allows for the continuum value of $t_0$ to vary, thereby determining this quantity with a comparable level of precision to that of the lattice scale. Using the resulting scales our measurement of the negative-parity ${\Omega }^{3/2^{-}}$ state is found to be consistent with the recently-discovered $\Omega (2012{)}^{-}$, which can therefore be assigned the quantum numbers $I(J^P)=0\left(3/2^{-}\right)$.

    ↳ hep-lathep-ph21 citations
30. 30*

    The Black Hole Formation -- Null Geodesic Correspondence

    Andrea Ianniccari🇨🇭 · Antonio J. Iovino🇮🇹 · Alex Kehagias🇬🇷 · Davide Perrone🇨🇭 · Antonio Riotto🇨🇭

    We provide evidence for a correspondence between the formation of black holes and the stability of circular null geodesics around the collapsing perturbation. We first show that the critical threshold of the compaction function to form a black hole in radiation is well approximated by the critical threshold for the appearance of the first unstable circular orbit in a spherically symmetric background. We also show that the critical exponent in the scaling law of the primordial black hole mass close to the threshold is set by the inverse of the Lyapunov coefficient of the unstable orbits when a self-similar stage is developed close to criticality.

    ↳ astro-ph.COgr-qchep-phhep-thPRL(2024)·30 citations
31. 31*

    Spin alignment of $K^{\ast }$ induced by strange-baryon density inhomogeneity

    Feng Li🇨🇳

    The difference between the spin alignments of $K^{\ast }$ and those of $\varphi$ at the low collision energies is a puzzle raised by the recent experiments. Unlike $\varphi$ meson, $K^{\ast }$, carrying a unit strange charge, should react to strange chemical potential ${\mu }_S$. In this paper, we shall first convince you that ${\mu }_S$ is not small in a brayon-rich medium for keeping strange neutrality, and then derive the spin alignment induced by the gradient of ${\mu }_S$, and hence of baryon chemical potential ${\mu }_B$, using linear response theory, with the transport coefficients expressed, without any approximation, in terms of the $K^{\ast }$'s in-medium spectral properties by employing Ward-Takahashi identity. It turns out that such an effect applies mainly to the particles whose longitudinal and transverse modes diverge, and induces only the local spin alignment in a static medium. The magnitudes of these coefficients will be further estimated under the quasi-particle approximation.

    ↳ nucl-thhep-phPRC(2024)·5 citations
32. 32*

    Forecasting the sensitivity of Pulsar Timing Arrays to gravitational wave backgrounds

    Stanislav Babak🇫🇷 · Mikel Falxa🇫🇷 · Gabriele Franciolini🇨🇭 · Mauro Pieroni🇨🇭

    Pulsar Timing Array (PTA) observations hinted towards the existence of a stochastic gravitational wave background (SGWB) in the nHz frequency band. Still, the nature of the SGWB signal cannot be confidently inferred from current data, and the leading explanation invokes mergers of supermassive black holes. If confirmed, such discovery would not only represent a turning point in our understanding of astrophysics, but it may severely limit the capability of searching for additional cosmological sources in the nHz frequency range. In this work, we build a simple framework to forecast the sensitivity of future PTA configurations and assess the parameter estimation of SGWB, which could consist of several contributions. We release the python code fastPTA implementing this framework and ready to use.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2024)·56 citations
33. 33*

    The cosmological constant and the weak gravity conjecture

    Yang Liu🇬🇧 · Antonio Padilla🇬🇧 · Francisco G. Pedro🇮🇹

    We examine the descent via membrane nucleation through a landscape of vacua where the cosmological constant is given by a combination of four-form fluxes. It has been shown that this descent can be slowed exponentially for very low curvature vacua close to Minkowski space in a wide class of models satisfying certain parametric conditions, providing a possible solution to the cosmological constant problem. We explore in detail whether or not those parametric conditions are compatible with the membrane weak gravity conjecture. Whilst it is true that there is often tension, we show that this is not always the case and present an explicit model where Minkowski space is absolutely stable and the weak gravity conjecture is satisfied. This corresponds to an extension of the Bousso-Polchinski model into a generalised DBI action for four-forms. We also clarify how the landscape should be populated in a consistent model.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2024)·6 citations
34. 34*

    Quantum thermodynamics of nonequilibrium processes in lattice gauge theories

    Zohreh Davoudi🇺🇸 · Christopher Jarzynski🇺🇸 · Niklas Mueller🇺🇸 · Greeshma Oruganti🇺🇸 · Connor Powers🇺🇸 · Nicole Yunger Halpern🇺🇸

    A key objective in nuclear and high-energy physics is to describe nonequilibrium dynamics of matter, e.g., in the early universe and in particle colliders, starting from the Standard Model. Classical-computing methods, via the framework of lattice gauge theory, have experienced limited success in this mission. Quantum simulation of lattice gauge theories holds promise for overcoming computational limitations. Because of local constraints (Gauss's laws), lattice gauge theories have an intricate Hilbert-space structure. This structure complicates the definition of thermodynamic properties of systems coupled to reservoirs during equilibrium and nonequilibrium processes. We show how to define thermodynamic quantities such as work and heat using strong-coupling thermodynamics, a framework that has recently burgeoned within the field of quantum thermodynamics. Our definitions suit instantaneous quenches, simple nonequilibrium processes undertaken in quantum simulators. To illustrate our framework, we compute the work and heat exchanged during a quench in a ${\mathbb{Z}}_2$ lattice gauge theory coupled to matter in 1+1 dimensions. The thermodynamic quantities, as functions of the quench parameter, evidence a phase transition. For general thermal states, we derive a simple relation between a quantum many-body system's entanglement Hamiltonian, measurable with quantum-information-processing tools, and the Hamiltonian of mean force, used to define strong-coupling thermodynamic quantities.

    ↳ quant-phcond-mat.stat-mechhep-lathep-ph+1PRL(2024)·25 citations
35. 35*

    A novel strategy to prove chiral symmetry breaking in QCD-like theories

    Luca Ciambriello🇮🇹 · Roberto Contino🇮🇹 · Andrea Luzio🇮🇹 · Marcello Romano🇫🇷 · Ling-Xiao Xu🇮🇹

    We demonstrate that chiral symmetry breaking occurs in the confining regime of QCD-like theories with $N_c$ colors and $N_f$ flavors. Our proof is based on a novel strategy, called `downlifting', by which solutions of the 't Hooft anomaly matching and persistent mass conditions for a theory with $N_f-1$ flavors are constructed from those of a theory with $N_f$ flavors, while $N_c$ is fixed. By induction, chiral symmetry breaking is proven for any $N_f\ge p_{min}$ in the confining regime, where $p_{min}$ is the smallest prime factor of $N_c$. The proof can be extended to $N_f<p_{min}$ under the additional assumption on the absence of phase transitions when quark masses are sent to infinity. Our results do not rely on assumptions on the spectrum of massless bound states other than the fact that they are color-singlet hadrons.

    ↳ hep-thhep-lathep-phPLB(2025)·10 citations
36. 36*

    On the Proof of Chiral Symmetry Breaking through Anomaly Matching in QCD-like Theories: An Exemplification

    Luca Ciambriello🇮🇹 · Roberto Contino🇮🇹 · Ling-Xiao Xu🇮🇹

    Our recent works revisit the proof of chiral symmetry breaking in the confining phase of four-dimensional QCD-like theories, i.e. $SU(N_c)$ gauge theories with $N_f$ flavors of vectorlike quarks in the fundamental representation. The analysis relies on the structure of 't Hooft anomaly matching and persistent mass conditions for theories with same $N_c$ and different $N_f$. In this paper, we work out concrete examples with $N_c=3$ and $N_c=5$ to support and elucidate the results in the companion papers. Within the same examples, we also test some claims made in earlier works.

    ↳ hep-thhep-lathep-phNPB(2025)·6 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.