Wed·Sep 4, 2024Wednesday·September 4, 2024

1. 01*

   Prompt photon production with two jets in POWHEG

   Tomáš Ježo🇩🇪 · Michael Klasen🇩🇪 · Alexander Neuwirth🇩🇪

   Prompt photon production is highly sensitive to the distribution of quarks and gluons in free protons and nuclei and an important baseline for phenomenological studies of the properties of the quark-gluon plasma. In this paper, we present a new calculation of the production of prompt photons in association with two jets at next-to-leading order in quantum chromodynamics matched to parton showers with the POWHEG method. This calculation extends our previous analysis of prompt photon production in association with one jet using \texttt{POWHEG+PYTHIA}. We investigate the role of the parton shower as an alternative description of the parton-to-photon fragmentation process and analyse correlations between the photon and the jets. In addition, we compare \texttt{POWHEG+PYTHIA} with \texttt{POWHEG+HERWIG} predictions, experimental ATLAS data for isolated photons, and a perturbative calculation at next-to-next-to-leading order. Both parton shower models bring the next-to-leading order prediction into good agreement with the experimental data and the next-to-next-to-leading order calculation.

   hep-phJHEP(2025)·5 citations
2. 02*

   Parton distribution functions and transverse momentum dependence of heavy mesons

   Fernando E. Serna🇨🇴 · Bruno El-Bennich🇧🇷 · Gastão Krein🇧🇷

   The leading Fock state light-front wave functions of heavy quarkonia and $D$ and $B$ mesons are obtained from the projections of their Bethe-Salpeter wave functions on the light front. We compute therefrom their leading-twist time-reversal even transverse momentum distributions and parton distribution functions. Mirroring the behavior of parton distribution amplitudes, the support of both distributions is increasingly narrower and shifted towards larger $x$ as a function of the meson mass. The dependence of $x$ and ${\text{k}}_{\perp }^2$ of the transverse distributions does not factorize into separate functions, and their fall-off with ${\text{k}}_{\perp }^2$ is much slower than that of light mesons.

   hep-phnucl-thPRD(2024)·14 citations
3. 03*

   Shedding Light on Mirror Dark Matter Using CDEX

   M. Tousif Raza🇺🇸

   Mirror dark matter, a hidden-sector counterpart to the Standard Model with identical particle content, could be detectable through photon-mirror-photon kinetic mixing $(ϵ)$. We present new constraints from CDEX-10 low-energy recoil data, establishing $ϵ<2\times 10^{-10}$ for mirror nuclear dark matter in the 10--56 GeV mass range. Projections for CDEX-300 (with 95 days of exposure) show significantly improved sensitivity, reaching $ϵ<3.75\times 10^{-11}$ for a local mirror halo temperature below 0.3 keV, surpassing existing constraints from LUX and positronium decays. These results demonstrate CDEX-300's unique capability to probe kinetic-mixing parameter space, providing stringent constraints on mirror dark matter models.

   hep-ph0 citations
4. 04*

   Probing $|V_{cs}|$ and lepton flavor universality through $D\to K_0^{\ast }(1430)\ell {\nu }_{\ell }$ decay

   Yin-Long Yang🇨🇳 · Hai-Jiang Tian🇨🇳 · Ya-Xiong Wang🇨🇳 · Hai-Bing Fu🇨🇳 · Tao Zhong🇨🇳 · Sheng-Quan Wang🇨🇳 · Dong Huang🇨🇳

   In this paper, we calculate the semileptonic decays $D\to K_0^{\ast }(1430)\ell {\nu }_{\ell }$ with $\ell =(e,\mu )$ induced by $c\to s\ell {\nu }_{\ell }$ transition. For the key component, $D\to K_0^{\ast }(1430)$ transition form factors (TFFs) $f_{\pm }(q^2)$ are calculated within the framework of QCD light cone sum rule. Then, we consider two scenarios for $K_0^{\ast }(1430)$-meson twist-2 distribution amplitude. For the scenario 1 (S1), we take the truncated form based on Gegenbauer polynomial series. Meanwhile, we also consider the scenario 2 (S2) constructed by light cone harmonic oscillator model, where the model parameters are fixed by the $K_0^{\ast }(1430)$-meson twist-2 distribution amplitude tenth-order $\xi$ moments calculated by using the background field theory. For the TFFs at a large recoil point, we have $f_{+}^{(S1)}(0)=0.597_{-0.121}^{+0.122}$ and $f_{-}^{(S1)}(0)=-0.136_{-0.035}^{+0.023}$, $f_{+}^{(S2)}(0)=0.663_{-0.134}^{+0.135}$, and $f_{-}^{(S2)}(0)=-0.202_{-0.046}^{+0.026}$. After extrapolating TFFs to the whole physical $q^2$ region, we calculate the branching fractions of $D^0\to K_0^{\ast +}(1430){\ell }^{-}{\bar{\nu }}_{\ell }$ and $D^{+}\to K_0^{\ast 0}(1430){\ell }^{+}{\nu }_{\ell }$, which at $10^{-4}$-order level for the S1 and S2 cases. Meanwhile, we predict the CKM matrix $|V_{cs}{|}^{(S1)}=0.973_{-0.183}^{+0.259},|V_{cs}{|}^{(S2)}=0.880_{-0.165}^{+0.234}$, and lepton flavor universality ${\mathcal{R}}_{K_0^{\ast }}^{(S1)}=0.768_{-0.368}^{+0.560},{\mathcal{R}}_{K_0^{\ast }}^{(S2)}=0.764_{-0.365}^{+0.555}$. Finally, we discuss the angular observables of forward-backward asymmetries, lepton polarization asymmetries, and $q^2$-differential flat terms for this decay.

   hep-phPRD(2024)·10 citations
5. 05*

   Next-to-soft threshold effects on Higgs boson production via bottom quark annihilation

   Goutam Das🇩🇪 · Aparna Sankar🇩🇪

   We examine the behavior of singular leading and sub-leading logarithms, commonly referred to as the soft-virtual (SV) and next-to-soft-virtual (NSV) terms, in the production of the Higgs boson via the bottom quark annihilation channel. We derive analytic expressions at the SV+NSV resummed level, up to next-to-next-to-next-to-leading logarithmic (N3LL) accuracy in perturbative QCD, applicable to both the inclusive production cross-section and rapidity distribution. This has been achieved using an existing resummation formalism based on factorization and renormalization group (RG) invariance. A phenomenological analysis of our resummed results is performed for the 13 TeV Large Hadron Collider. Furthermore, we present the SV coefficients at the fourth order in the strong coupling and explore the impact of next-to-next-to-next-to-next-to-leading logarithmic (N4LL) resummation on the total cross-section.

   hep-phPRD(2025)·10 citations
6. 06*

   Entropy in Toy Regge models

   M.A.Braun🇷🇺

   The probabilistic interpretation of the standard Regge-Gribov model with triple pomeron interactions is discussed. It is stated that introduction of probabilities within this model is not unique and depends on what is meant under the relevant substructures, The traditional interpretation in terms of partons (quarks and gluons) is shown to be external to the model, imported from the QCD, and actually referring to the single pomeron exchange without interactions. So this interpretation actually forgets the model as such. Alternative probabilities based on the pomerons as basic quantities within the model are discussed. Two different approaches are considered, based either on the pomerons in Fock's expansion of the wave function or on pomeron propagators in Feynman diagrams. These pomeron probabilities and entropy turn out to be very different from the mentioned standard ones in the purelyp obabilistic treatment. The entropy, in particular, either rises with the rapidity and saturates at a certain fixed value or first rises, reaches some maximum and goes down to zero afterwards. Possible observable manifestations of these probabilities and entropy are to be seen in the distributions of the cross-section in powers of the coupling constants to the participants. 23

   hep-phnucl-thEur.Phys.J.Plus(2025)·3 citations
7. 07*

   Various Illustrative Brief Glances at the Flavour-Cryptoexotic Tetraquark States

   Wolfgang Lucha🇦🇹

   Constituting the largest subset of multiquark states so far observed by experiment, tetraquark mesons carrying overall quark flavour quantum numbers identical to those of the (conventional) quark-antiquark mesons necessitate their particularly deliberate phenomenological analyses. A collection of (more or less recent) insights specific to the latter subclass of exotic hadrons bears the promise to enable even significant improvement in the understanding of these hadrons by theoretical approaches such as, among others, the framework of QCD sum rules.

   hep-phhep-exnucl-thEPJ Web Conf.(2024)·0 citations
8. 08*

   Peculiarities of Regge cuts in QCD

   V.S. Fadin🇷🇺

   As is known from the classical theory of complex angular momenta, along with the Regge poles in the complex $j$ - plane should be cuts that are generated by the poles. In QCD, the cuts are generated by exchanges of the Reggeized gluons, whose properties are strikingly different from the properties of Reggeons in classical theory, which leads to peculiarities of the formation of the cuts. The talk is devoted to the discussion of these peculiarities.

   hep-phPhys.Part.Nucl.Lett.(2025)·3 citations
9. 09*

   Application of Kolmogorov-Arnold Networks in high energy physics

   E. Abasov🇷🇺 · P. Volkov🇷🇺 · G. Vorotnikov🇷🇺 · L. Dudko🇷🇺 · A. Zaborenko🇷🇺 · E. Iudin🇷🇺 · A. Markina🇷🇺 · M. Perfilov🇷🇺

   Kolmogorov-Arnold Networks represent a recent advancement in machine learning, with the potential to outperform traditional perceptron-based neural networks across various domains as well as provide more interpretability with the use of symbolic formulas and pruning. This study explores the application of KANs to specific tasks in high-energy physics. We evaluate the performance of KANs in distinguishing multijet processes in proton-proton collisions and in reconstructing missing transverse momentum in events involving dark matter.

   hep-phMoscow Univ.Phys.Bull.(2024)·3 citations
10. 10*

    Inclusive photoproduction of vector quarkonium in ultra-peripheral collisions at the LHC

    Jean-Philippe Lansberg🇫🇷 · Kate Lynch🇮🇪 · Charlotte Van Hulse🇪🇸 · Ronan McNulty🇮🇪

    We explore the possibility of using ultra-peripheral proton-lead collisions at the LHC to study inclusive vector-quarkonium photoproduction, that occurs when a quasi-real photon emitted by a fully stripped lead ion breaks a proton to produce a vector quarkonium. Owing to the extremely large energies of the colliding hadrons circulating in the LHC, the range of accessible photon-nucleon centre-of-mass energies, W_gamma+p, largely exceeds what has been and will be studied at lepton-hadron colliders, HERA and the EIC. We perform a tune to HERA photoproduction data, use this tune to predict the yields of photoproduced J/psi, and estimate the corresponding transverse-momentum reach at LHC experiments. We also model the hadroproduction background and demonstrate that inclusive photoproduction can be isolated at the LHC from such background by imposing constraints on the hadronic activity in the lead-going direction at mid, forward, or far-forward rapidities depending on the capability of the detector under consideration. We find that the resulting cross sections are large enough to be measured by ALICE, ATLAS, CMS, and LHCb. We estimate the background-to-signal ratio after isolation to be of the order of 0.001 and 0.1 in the low and large transverse-momentum regions, respectively. In addition, we propose and assess the Jacquet-Blondel method to reconstruct the photon-nucleon centre-of-mass energy and the fractional energy of the quarkonium with respect to the photon.

    hep-phhep-exnucl-exnucl-thEPJC(2025)·10 citations
11. 11*

    Inclusive $\mathrm{J}/\psi$ production in forward proton-proton and proton-lead collisions at high energy

    Patricia Gimeno-Estivill🇫🇮 · Tuomas Lappi🇫🇮 · Heikki Mäntysaari🇫🇮

    We calculate the cross section for forward $\mathrm{J}/\psi$ production in proton-proton and minimum bias proton-lead collisions using the Color Glass Condensate (CGC) and Non-Relativistic QCD (NRQCD) formalism consistently with Deep Inelastic Scattering data. The cross section for color singlet states is sensitive to a 4-point correlator of Wilson lines for which we describe in the Gaussian approximation in the large-$N_c$ limit. Furthermore, we quantify the importance of finite-$N_c$ corrections to have a small $\sim 12\%$ effect. In contrast with the generic NRQCD expectation, we show that the color singlet contribution is only $15\%$ to the total cross section. We also compare our predictions for $\mathrm{J}/\psi$ production as well as for the nuclear modification ratio $R_{pPb}$ to LHCb and ALICE data. We find a good agreement at forward rapidities, except at low transverse momenta where the cross sections are overestimated.

    hep-phPRD(2024)·4 citations
12. 12*

    Constraining neutrinophilic mediators at FASER$\nu$, FLArE and FASER$\nu$2

    Weidong Bai🇨🇳 · Jiajun Liao🇨🇳 · Hongkai Liu🇮🇱

    High energy collider neutrinos have been observed for the first time by the FASER$\nu$ experiment. The detected spectrum of collider neutrinos scattering off nucleons can be used to probe neutrinophilic mediators with GeV-scale masses. We find that constraints on the pseudoscalar (axial vector) neutrinophilic mediator are close to the scalar (vector) case since they have similar cross section in the neutrino massless limit. We perform an analysis on the measured muon spectra at FASER$\nu$, and find that the bounds on the vector mediator from the current FASER$\nu$ data are comparable to the existing bounds at $m_{Z^{\prime }}\approx 0.2$ GeV. We also study the sensitivities to a neutrinophilic mediator at future Forward Physics Facilities including FLArE and FASER$\nu$2 by using both the missing transverse momentum and the charge identification information. We find that FLArE and FASER$\nu$2 can impose stronger bounds on both the scalar and vector neutrinophilic mediators than the existing bounds. The constraints on the scalar mediator can reach 0.08 (0.1) for $m_{\varphi }\lesssim 1$ GeV with (without) muon charge identification at FASER$\nu$2.

    hep-phhep-exhep-thPRD(2024)·5 citations
13. 13*

    Aspects of holographic Langevin diffusion in the presence of anisotropic magnetic field

    Qi Zhou🇨🇳 · Ben-Wei Zhang🇨🇳

    We study the holographic Langevin diffusion coefficients of a heavy quark, when traveling through a strongly coupled anisotropic plasma in the presence of magnetic field~$\mathcal{B}$. In particular, we clarified how motion velocities shape momentum broadening and its directional dependence. It is observed that the transverse Langevin diffusion coefficients depend more on the direction of motion rather than the directions of momentum diffusion at the ultra-fast limit, while an opposite conclusion is found when the moving speed is sufficiently low. For the Longitudinal Langevin diffusion coefficient, we find that motion perpendicular to~$\mathcal{B}$ affects the Langevin coefficients stronger at any fixed velocity. We should also emphasize that all five Langevin coefficients are becoming larger with increasing velocity. We find that the universal relation~${\kappa }^{\parallel }>{\kappa }^{\perp }$ in the isotropic background, is broken in a different new case that a quark moving paralleled to~$\mathcal{B}$. This is one more particular example where the violation of the universal relation occurs for the anisotropic background. Further, we find the critical velocity of the violation will become larger with increasing~$\mathcal{B}$.

    hep-phPLB(2025)·2 citations
14. 14*

    Manifestation of $a_1(1260)$ meson in the process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0$

    I.V. Obraztsov🇷🇺 · A.S. Rudenko🇷🇺 · A.I. Milstein🇷🇺

    The charge asymmetry in the process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0$ is studied taking into account a longitudinal polarization of electrons (positrons). The asymmetry arises due to interference of amplitudes corresponding to production of pions in C-odd and C-even states. It is a manifestation of $a_1(1260)$ meson in the intermediate state. Polarization leads to additional correlations in the differential cross section, which simplifies the experimental study of the process. It is shown that the charge asymmetry can reach several percent.

    hep-phhep-exPRD(2024)·1 citation
15. 15*

    Experimental measurements outlasting MSSM-30 spectra

    S. AbdusSalam🇮🇷 · S.S. Barzani🇮🇷 · M. Mohammadidoust🇮🇷 · S.A. Ojaghi🇮🇷 · L. Velasco-Sevilla🇰🇷

    Benchmarks for beyond the Standard Model (BSM) searches are mostly constructed around particular features of interest related to the experiment under consideration without giving due address to the results from other experiments. In this article, we present a 30-parameter MSSM phenomenological framework and benchmark points relevant for the long-lived particles and Higgs boson decays to BSM particle studies. These are extracted via scans of the model parameter space compatible with low-energy constraints from electroweak physics, B-physics, the dipole moment of the electron, and cold dark matter relic density measurements. We present four benchmark points that are illustrative on how light values of supersymmetric particles can still be. Neutralinos and charginos can be lighter than W-boson mass in sharp contrast to the expectations by conclusions derived based on simplified supersymmetric models.

    hep-ph0 citations
16. 16*

    Comment on "Excluding Primordial Black Holes as Dark Matter Based on Solar System Ephemeris"

    James M. Cline🇨🇦

    It was recently claimed (arXiv:2408.10799) that solar system ephemeris data can exclude primordial black hole (PBH) dark matter in the mass range $10^{18}$-$10^{22}$g. We show that this conclusion is based on an implausible, implicit assumption; namely the uncertainty on the solar system mass within 50 au is as small as the uncertainty on the mass of the sun. Correcting for this error, we find that ephemeris data can only constrain PBH's with mass below $10^{16}$g, which is already excluded by constraints on their evaporation via Hawking radiation. Correcting a further error concerning the time-averaged rate of such fluctuations nullifies even this weaker constraint.

    hep-phastro-ph.COgr-qcRes.Notes AAS(2024)·2 citations
17. 17*

    Implications of first neutrino-induced nuclear recoil measurements in direct detection experiments

    D. Aristizabal Sierra🇨🇱 · N. Mishra🇺🇸 · L. Strigari🇺🇸

    PandaX-4T and XENONnT have recently reported the first measurement of nuclear recoils induced by the ${}^8$B solar neutrino flux, through the coherent elastic neutrino-nucleus scattering (CE$\nu$NS) channel. As long anticipated, this is an important milestone for dark matter searches as well as for neutrino physics. This measurement means that these detectors have reached exposures such that searches for low mass, $\lesssim 10$ GeV dark matter cannot be analyzed using the background-free paradigm going forward. It also opens a new era for these detectors to be used as neutrino observatories. In this paper we assess the sensitivity of these new measurements to new physics in the neutrino sector. We focus on neutrino non-standard interactions (NSI) and show that -- despite the still moderately low statistical significance of the signals -- these data already provide valuable information. We find that limits on NSI from PandaX-4T and XENONnT measurements are comparable to those derived using combined COHERENT CsI and LAr data, as well as those including the latest Ge measurement. Furthermore, they provide sensitivity to pure $\tau$ flavor parameters that are not accessible using stopped-pion or reactor sources. With further improvements of statistical uncertainties as well as larger exposures, forthcoming data from these experiments will provide important, novel results for CE$\nu$NS-related physics.

    hep-phastro-ph.COhep-exnucl-ex+1PRD(2025)·37 citations
18. 18*

    FPF@FCC: Neutrino, QCD, and BSM Physics Opportunities with Far-Forward Experiments at a 100 TeV Proton Collider

    Roshan Mammen Abraham🇺🇸 · Jyotismita Adhikary🇵🇱 · Jonathan L. Feng🇺🇸 · Max Fieg🇺🇸 · Felix Kling🇩🇪 · Jinmian Li🇨🇳 · Junle Pei🇨🇳 · Tanjona R. Rabemananjara🇳🇱 · Juan Rojo🇳🇱 · Sebastian Trojanowski🇵🇱

    Proton-proton collisions at energy-frontier facilities produce an intense flux of high-energy light particles, including neutrinos, in the forward direction. At the LHC, these particles are currently being studied with the far-forward experiments FASER/FASER$\nu$ and SND@LHC, while new dedicated experiments have been proposed in the context of a Forward Physics Facility (FPF) operating at the HL-LHC. Here we present a first quantitative exploration of the reach for neutrino, QCD, and BSM physics of far-forward experiments integrated within the proposed Future Circular Collider (FCC) project as part of its proton-proton collision program (FCC-hh) at $\sqrt{s}\simeq 100$ TeV. We find that $10^9$ electron/muon neutrinos and $10^7$ tau neutrinos could be detected, an increase of several orders of magnitude compared to (HL-)LHC yields. We study the impact of neutrino DIS measurements at the FPF@FCC to constrain the unpolarised and spin partonic structure of the nucleon and assess their sensitivity to nuclear dynamics down to $x\sim 10^{-9}$ with neutrinos produced in proton-lead collisions. We demonstrate that the FPF@FCC could measure the neutrino charge radius for ${\nu }_e$ and ${\nu }_{\mu }$ and reach down to five times the SM value for ${\nu }_{\tau }$. We fingerprint the BSM sensitivity of the FPF@FCC for a variety of models, including dark Higgs bosons, relaxion-type scenarios, quirks, and millicharged particles, finding that these experiments would be able to discover LLPs with masses as large as 50 GeV and couplings as small as $10^{-8}$, and quirks with masses up to 10 TeV. Our study highlights the remarkable opportunities made possible by integrating far-forward experiments into the FCC project, and it provides new motivation for the FPF at the HL-LHC as an essential precedent to optimize the forward physics experiments that will enable the FCC to achieve its full physics potential.

    hep-phhep-exnucl-exJHEP(2025)·37 citations
19. 19*

    Primordial Black Hole Hot Spots and Out-of-Equilibrium Dynamics

    Jacob Gunn🇮🇹 · Lucien Heurtier🇬🇧 · Yuber F. Perez-Gonzalez🇬🇧 · Jessica Turner🇬🇧

    When light primordial black holes (PBHs) evaporate in the early Universe, they locally reheat the surrounding plasma, creating hot spots with temperatures that can be significantly higher than the average plasma temperature. In this work, we provide a general framework for calculating the probability that a particle interacting with the Standard Model can escape the hot spot. More specifically, we consider how these hot spots influence the generation of the baryon asymmetry of the Universe (BAU) in leptogenesis scenarios, as well as the production of dark matter (DM). For leptogenesis, we find that PBH-produced right-handed neutrinos can contribute to the BAU even if the temperature of the Universe is below the electroweak phase transition temperature, since sphaleron processes may still be active within the hot spot. For DM, particles emitted by PBHs may thermalise with the heated plasma within the hot spot, effectively preventing them from contributing to the observed relic abundance. Our work highlights the importance of including hot spots in the interplay of PBHs and early Universe observables

    hep-phastro-ph.COastro-ph.HEJCAP(2025)·22 citations
20. 20*

    Modular flavored dark matter

    Alexander Baur🇲🇽 · Mu-Chun Chen🇺🇸 · V. Knapp-Perez🇺🇸 · Saul Ramos-Sanchez🇲🇽

    Discrete flavor symmetries have been an appealing approach for explaining the observed flavor structure, which is not justified in the Standard Model (SM). Typically, these models require a so-called flavon field in order to give rise to the flavor structure upon the breaking of the flavor symmetry by the vacuum expectation value (VEV) of the flavon. Generally, in order to obtain the desired vacuum alignment, a flavon potential that includes additional so-called driving fields is required. On the other hand, allowing the flavor symmetry to be modular leads to a structure where the couplings are all holomorphic functions that depend only on a complex modulus, thus greatly reducing the number of parameters in the model. We show that these elements can be combined to simultaneously explain the flavor structure and dark matter (DM) relic abundance. We present a modular model with flavon vacuum alignment that allows for realistic flavor predictions while providing a successful fermionic DM candidate.

    hep-phhep-thJHEP(2024)·3 citations
21. 21*

    Enhanced Dark Matter Abundance in First-Order Phase Transitions

    Rouzbeh Allahverdi🇺🇸 · Cash Hauptmann🇺🇸 · Peisi Huang🇺🇸

    We propose a novel scenario to obtain the correct relic abundance for thermally under-produced dark matter. This scenario utilizes a strongly first-order phase transition at temperature $T_{\mathrm{PT}}$ that gives rise to dark matter mass $m$. Freeze-out in the broken phase can yield the desired abundance in the entire region currently allowed by observational bounds and theoretical constraints for $10^2{T}_{\mathrm{PT}}\lesssim m\lesssim 10^4{T}_{\mathrm{PT}}$. We show that the accompanying gravitational waves are strong enough to be detected by many upcoming and proposed experiments. This, in tandem with dark matter indirect searches, provides a multi-messenger probe of such models. Positive signals in the future can help reconstruct the potential governing the phase transition and shed light on an underlying particle physics realization.

    hep-phastro-ph.COastro-ph.HEhep-thPRD(2024)·8 citations
22. 22*

    The Dark Dimension and the Grand Unification of Forces

    Jonathan J. Heckman🇺🇸 · Cumrun Vafa🇺🇸 · Timo Weigand🇩🇪 · Fengjun Xu🇨🇳

    The dark dimension scenario, predicting one extra mesoscopic dimension in the micron range, has emerged by applying various Swampland principles to the dark energy. In this note we find that realizing the grand unification of gauge forces is highly constraining in this context. Without actually constructing any GUT models, we argue that the mere assumption of grand unification of forces in this scenario, together with the experimental bounds on massive replicas of the Standard Model gauge bosons, predicts an upper bound for the GUT scale, $M_{GUT}\lesssim 10^{16}\mathrm{GeV}$. Combined with the experimental bound on the proton lifetime, this predicts that the $X$ gauge boson mediating proton decay is a 5d solitonic string of Planckian tension stretched across a length scale $L\sim (1-10\mathrm{TeV}{)}^{-1}$ ending on gauge branes of the same diameter $\sim L$. This leads to a mass of $M_X\sim 10^{15}-10^{16}\mathrm{GeV}$. In particular assuming grand unification in the dark dimension scenario results in a tower of Kaluza-Klein excitations of Standard Model gauge bosons on the gauge branes in the 1-10 TeV range. This suggests that the diameter/separation $L$ of the gauge branes correlates with both the weak scale $\sim 1/L$ near a TeV {\it and} the GUT scale $\sim M_5^{2}L$ at $10^{16}\mathrm{GeV}$.

    ↳ hep-thhep-phPRD(2025)·18 citations
23. 23*

    Measuring the Time Variation of the Fine-structure Constant with Quasars Detected by LAMOST

    Jin-Nan Wei🇨🇳 · Rui-Jie Chen🇨🇳 · Jun-Jie Wei · Martín López-Corredoira🇨🇳 · Xue-Feng Wu🇨🇳

    The [O III] $\lambda \lambda 4960,5008$ emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constant $\alpha$ over cosmic time. In this work, we utilize the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) quasar survey, for the first time, to measure the relative $\alpha$ variation $\Delta \alpha /\alpha$ in time through the [O III] doublet method. From the LAMOST Data Release 9 quasar catalog, we refine a sample of 209 quasar spectra with strong and narrow [O III] emission lines over a redshift range of $0<z<0.8$. Analysis on all of the 209 spectra obtains $\Delta \alpha /\alpha =(0.5\pm 3.7)\times 10^{-4}$, which suggests that there is no evidence of varying $\alpha$ on the explored cosmological timescales. Assuming a linear variation, the mean rate of change in $\Delta \alpha /\alpha$ is limited to be $(-3.4\pm 2.4)\times 10^{-13}$ $\mathrm{y}{\mathrm{r}}^{-1}$ in the last 7.0 Gyr. While our LAMOST-based constraint on $\Delta \alpha /\alpha$ is not competitive with those of the Sloan Digital Sky Survey (SDSS) quasar observations, our analysis serves to corroborate the results of SDSS with another independent survey.

    ↳ astro-ph.COgr-qchep-phhep-thRes.Astron.Astrophys.(2024)·5 citations
24. 24*

    Implications of cosmologically coupled black holes for pulsar timing arrays

    Marco Calzà🇮🇹 · Francesco Gianesello🇮🇹 · Massimiliano Rinaldi🇮🇹 · Sunny Vagnozzi🇮🇹

    It has been argued that realistic models of (singularity-free) black holes (BHs) embedded within an expanding Universe are coupled to the large-scale cosmological dynamics, with striking consequences, including pure cosmological growth of BH masses. In this pilot study, we examine the consequences of this growth for the stochastic gravitational wave background (SGWB) produced by inspiraling supermassive cosmologically coupled BHs. We show that the predicted SGWB amplitude is enhanced relative to the standard uncoupled case, while maintaining the ${\Omega }_{\text{gw}}\propto f^{2/3}$ frequency scaling of the spectral energy density. For the case where BH masses grow with scale factor as $M_{\text{bh}}\propto a^3$, thus contributing as a dark energy component to the cosmological dynamics, ${\Omega }_{\text{gw}}$ can be enhanced by more than an order of magnitude. This has important consequences for the SGWB signal detected by pulsar timing arrays, whose measured amplitude is slightly larger than most theoretical predictions for the spectrum from inspiraling binary BHs, a discrepancy which can be alleviated by the cosmological mass growth mechanism.

    ↳ gr-qcastro-ph.COhep-phhep-thSci.Rep.(2024)·38 citations
25. 25*

    Extreme softening of QCD phase transition under weak acceleration: first principle Monte Carlo results for gluon plasma

    M. N. Chernodub🇫🇷 · V. A. Goy🇷🇺 · A. V. Molochkov🇷🇺 · D. V. Stepanov🇷🇺 · A. S. Pochinok🇷🇺

    We study the properties of gluon plasma subjected to a weak acceleration using first-principle numerical Monte Carlo simulations. We use the Luttinger (Tolman-Ehrenfest) correspondence between temperature gradient and gravitational field to impose acceleration in imaginary time formalism. Under acceleration, the system resides in global thermal equilibrium. Our results indicate that even the weakest acceleration up to $a\simeq 16$ MeV drastically softens the deconfinement phase transition, converting the first-order phase transition of a static system to a soft crossover for accelerating gluons. The accelerating environment can be relevant to the first moments of the early Universe and the initial glasma regime of relativistic heavy ion collisions. In particular, our results imply that the acceleration, if present, may also inhibit the detection of the thermodynamic phase transition from quark-gluon plasma to the hadronic phase.

    ↳ hep-lathep-phhep-thPRL(2025)·19 citations
26. 26*

    Primordial black holes: formation, spin and type II

    Tomohiro Harada🇯🇵

    Primordial black holes (PBHs) may have formed through the gravitational collapse of cosmological perturbations that were generated and stretched during the inflationary era, later entering the cosmological horizon during the decelerating phase, if their amplitudes were sufficiently large. In this review paper, we will briefly introduce the basic concept of PBHs and review the formation dynamics through this mechanism, the estimation of the initial spins of PBHs and the time evolution of type II fluctuations, with a focus on the radiation-dominated and (early) matter-dominated phases.

    ↳ gr-qcastro-ph.COhep-phUniverse(2024)·14 citations
27. 27*

    Fragments of harmony amid apparent chaos: a closer look at the X-ray quasi-periodic eruptions of the galaxy RX J1301.9+2747

    Margherita Giustini🇪🇸 · Giovanni Miniutti🇪🇸 · Riccardo Arcodia🇺🇸 · Adelle Goodwin🇦🇺 · Kate D. Alexander🇺🇸 · Joheen Chakraborty🇺🇸 · Johannes Buchner🇩🇪 · Peter Kosec🇺🇸 · Richard Saxton🇫🇷 · Matteo Bonetti🇮🇹 · Alessia Franchini🇮🇹 · Taeho Ryu🇩🇪 and 8 other authors

    Quasi-periodic eruptions (QPEs) are an extreme X-ray variability phenomenon associated with low-mass supermassive black holes. First discovered in the nucleus of the galaxy GSN 069, they have been so far securely detected in five other galaxies, including RX J1301.9+2747. When detected, the out-of-QPE emission (quiescence) is consistent with the high-energy tail of thermal emission from an accretion disk. We present the X-ray and radio properties of RX J1301.9+2747, both in quiescence and during QPEs. We analyse X-ray data taken during five XMM-Newton observations between 2000 and 2022. The last three observations were taken in coordination with radio observations with the Karl G. Jansky Very Large Array. We also make use of EXOSAT, ROSAT, and Chandra archival observations taken between 1983 and 2009. XMM-Newton detected 34 QPEs of which 8 have significantly lower amplitudes than the others. No correlated radio/X-ray variability was observed during QPEs. In terms of timing properties, the QPEs in RX J1301.9+2747 do not exhibit the striking regularity observed in the discovery source GSN 069. In fact there is no clear repetition pattern between QPEs: the average time separation between their peaks is about four hours, but it can be as short as one, and as long as six hours. The QPE spectral properties of RX J1301.9+2747 as a function of energy are however very similar to those of GSN 069 and of other QPE sources. The quiescent emission of RX J1301.9+2747 is more complex than that of GSN 069, as it requires a soft X-ray excess-like component in addition to the thermal emission from the accretion disk. Its long-term X-ray quiescent flux variations are of low-amplitude and not strictly monotonic, with a general decay over $\sim 22$ years. We discuss our observational results in terms of some of the ideas and models that have been proposed so far for the physical origin of QPEs.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phAstron.Astrophys.(2024)·31 citations
28. 28*

    Symmetric Mass Generation with four SU(2) doublet fermions

    Nouman Butt🇺🇸 · Simon Catterall🇺🇸 · Anna Hasenfratz🇺🇸

    We study a single exactly massless staggered fermion in the fundamental representation of an $SU(2)$ gauge group. We utilize an nHYP-smeared fermion action supplemented with additional heavy Pauli-Villars fields which serve to decrease lattice artifacts. The phase diagram exhibits a clear two-phase structure with a conformal phase at weak coupling and a novel new phase, the Symmetric Mass Generation (SMG) phase, appearing at strong coupling. The SMG phase is confining with all states gapped and chiral symmetry unbroken. Our finite size scaling analysis provides strong evidence that the phase transition between these two phases is continuous, which would allow for the existence of a continuum SMG phase. Furthermore, the RG flows are consistent with a $\beta$-function that vanishes quadratically at the new fixed point suggesting that the $N_f=4$ flavor SU(2) gauge theory lies at the opening of the conformal window.

    ↳ hep-lathep-phhep-thPRL(2025)·19 citations
29. 29*

    Primordial black holes from an interrupted phase transition

    Wen-Yuan Ai🇬🇧 · Lucien Heurtier🇬🇧 · Tae Hyun Jung🇰🇷

    We propose a new mechanism of primordial black hole formation via an interrupted phase transition during the early matter-dominated stage of reheating after inflation. In reheating, induced by the decay of a pressureless fluid dominating the Universe at the end of inflation, dubbed as reheaton, the temperature of the radiation bath typically increases, reaching a maximum temperature $T_{\max }$, and then decreases. We consider a first-order phase transition induced by the increase of the temperature that is aborted as $T_{\max }$ is higher than the critical temperature but not sufficiently high for the bubble nucleation rate to overcome the expansion of the Universe. Although bubbles never fully occupy the space, some may be nucleated and expand until the temperature once again decreases to the critical temperature. We argue that these bubbles shrink and disappear as the temperature drops further, leaving behind macroscopic spherical regions with positive density perturbations. These perturbed regions accrete the surrounding matter (reheatons) and eventually collapse into primordial black holes whose mass continues to grow until the onset of radiation domination. We estimate the abundance of these primordial black holes in terms of the bubble nucleation rate at $T_{\max }$, and demonstrate that the abundance can be significantly large from a phenomenological perspective.

    ↳ astro-ph.COgr-qchep-phPRD(2026)·42 citations
30. 30*

    The Axion is Going Dark

    Markus Dierigl🇩🇪 · Dušan Novičić🇩🇪

    In this work we explore the effect of a non-Abelian dark sector gauge group that couples to the axion field. In particular, we analyze effects that arise if the dark sector gauge group mixes topologically with the Standard Model. This is achieved by gauging a subgroup of the global center 1-form symmetries which embeds non-trivially in both the visible as well as the dark sector gauge groups. Leaving the local dynamics unchanged, this effect modifies the quantization conditions for the topological couplings of the axion, which enter the estimate of a lower bound on the axion-photon coupling. In the presence of a dark sector this lower bound can be reduced significantly, which might open up interesting new parameter regions for axion physics. We further determine the allowed exotic matter representations in the presence of topological mixing with a dark sector, explore the generalized categorical symmetries of such axion theories, and comment on other model-independent phenomenological consequences.

    ↳ hep-thhep-phJHEP(2024)·10 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.