Fri·Aug 16, 2024Friday·August 16, 2024

1. 01*

   Exploring the Hidden Valley at MATHUSLA

   Samuel Liebersbach🇺🇸 · Pearl Sandick🇺🇸 · Abel Shiferaw🇺🇸 · Yue Zhao🇺🇸

   Hidden valley models naturally predict numerous long-lived particles, the distinctive signatures of which would be compelling evidence for a hidden valley scenario. As these are typically low energy particles, they pose a challenge in terms of passing energy triggers in traditional searches at the Large Hadron Collider. The MATHUSLA experiment is specifically designed for the purpose of detecting long-lived particles. It also has the capability of detecting lower energy particles relative to ATLAS and CMS. In this paper, we assess MATHUSLA's potential for effectively probing hidden valley models. As a benchmark, we assume the hidden valley sector communicates with Standard Model sectors via a heavy vector propagator that couples to Standard Model quarks as well as hidden valley quarks. We model the showering and hadronization in the hidden valley sector using PYTHIA, and study the detector acceptance as a function of the hidden valley meson's lifetime. We find that MATHUSLA possesses significant capabilities to explore previously uncharted parameter space within hidden valley models.

   hep-phNPB(2025)·4 citations
2. 02*

   Collision Energy Dependence of Particle Ratios and Freeze-out Parameters in Ultra Relativistic Nucleus Nucleus Collisions

   Iqbal Mohi Ud Din (1)🇮🇳 · Sameer Ahmad Mir (1)🇮🇳 · Nasir Ahmad Rather (1)🇮🇳 · Saeed Uddin (1)🇮🇳 · Rameez Ahmad Parra (2) ((1) Jamia Millia Islamia (2) University of Kashmir)🇮🇳

   This work investigates the thermo-chemical freeze-out condition of the multi-component hot and dense hadron resonance gas (HRG) formed in the ultra-relativistic nucleus-nucleus collisions (URNNC). The van der Waals (VDW) type model used in the present analysis incorporates the repulsive as well as attractive interactions among the hadrons. The baryons (antibaryons) are treated as incompressible objects. Using this theoretical approach the values of the model freeze-out parameters of the system are extracted over a wide range of collision energy by analyzing experimental data on like-mass antibaryon to baryon ratios. The same set of parameters is found to explain the energy dependence of several other particle ratios quite satisfactorily. We find that the horn-like structures seen in the ratios of strange particles to pions as a function of the collision energy cannot be explained by the VDW-HRG model alone without considering the strangeness imbalance effect in the system. We have compared our freeze-out line with those obtained earlier. The correlation between the $\bar{p}/p$ and $K^{-}/K^{+}$ ratios is also examined.

   hep-phnucl-thNPA(2025)·9 citations
3. 03*

   Mixing angle between ${}^3{P}_1$ and ${}^1{P}_1$ states in heavy axial vector mesons within the QCD sum rules framework

   T.M.Aliev🇹🇷 · S.Bilmis🇹🇷 · M.Savci🇹🇷

   In this study, we calculate the mixing angles between the axial-vector mesons $D_{1(s1)}-D_{1(s1)}^{\prime }$ and $B_{1(s1)}-B_{1(s1)}^{\prime }$ using the QCD sum rules approach. Our results are ${\theta }_1=28.2\pm 0.6^{\circ }$, ${\theta }_2=26.6\pm 0.6^{\circ }$, ${\theta }_3=38.6\pm 0.1^{\circ }$, and ${\theta }_4=38.5\pm 0.1^{\circ }$. These values are in good agreement with the predictions of Heavy Quark Effective Theory, particularly for the mixing angle $\theta =35.3^{\circ }$, and are compatible with several existing results in the literature. The predicted mixing angles can be tested through the analysis of semileptonic decays such as $B_c\to B_1\ell \nu$, $B_c\to B_{s1}^0\ell \nu$, $B_s\to D_{s1}\ell \nu$, and $B_s\to D_{s1}^{\prime }\ell \nu$, which can be investigated at experimental facilities such as LHCb and Belle II.

   hep-phPRD(2025)·2 citations
4. 04*

   New renormalization scheme in the two Higgs doublet models

   Shinya Kanemura🇯🇵 · Mariko Kikuchi🇯🇵 · Kei Yagyu🇯🇵

   We propose a new renormalization scheme in the two Higgs doublet models with a softly-broken $Z_2$ symmetry and CP-conservation in the Higgs sector. In this scheme, counterterms for mixing angles of the Higgs bosons are determined by using the decay rates of the discovered Higgs boson $h$, $i.e.$, $h\to {\tau }^{+}{\tau }^{-}$ and $h\to Z{Z}^{\ast }\to Z{\ell }^{+}{\ell }^{-}$ at next leading order (NLO) instead of using the renormalized two-point functions which are adopted in the previous scheme. We require that the decay rates at NLO are determined to be the corresponding predictions at NLO in the Standard Model (SM) times square of the scaling factor which describes the deviation of $h$ couplings at tree level from the SM value. The mixing angles then maintain the meaning of the ``alignmentness", $i.e.$, how the properties of $h$ are close to the SM predictions, while they lose such meaning in the previous scheme. We compare the predictions of the decay rates at NLO given in the new scheme and those in the previous scheme.

   hep-phPLB(2024)·4 citations
5. 05*

   Double and Triple Higgs Production to probe the Electroweak Phase Transition

   Lisa Biermann🇩🇪 · Christoph Borschensky🇩🇪 · Christoph Englert🇬🇧 · Margarete Mühlleitner🇩🇪 · Wrishik Naskar🇬🇧

   The production of three Higgs bosons could be a stretch goal for the LHC and a strategic case for future colliders. In this work, we analyse the phenomenological prospects of (neutral) triple Higgs compared to di-Higgs boson production, for a range of Higgs-sector extensions from a strong first-order electroweak phase transition perspective. In parallel, we include constraints from existing exotics and Higgs boson measurements that further limit the parameter space of such models. Resonance contributions offer large modifications in particular for triple Higgs production, albeit starting from a small SM expectation. With enhancements of order 40 over the SM, however, experimental efforts to obtain limits at the HL-LHC are well-motivated and well-placed. This is further highlighted by the potential of these processes to inform the investigation of the thermal history of our universe.

   hep-phhep-exPRD(2024)·14 citations
6. 06*

   Multi-Jet Merging in Deep Inelastic Scattering with Pythia

   Joni Laulainen🇫🇮 · Ilkka Helenius🇫🇮 · Christian T. Preuss🇩🇪

   We aim to improve the modelling of deep inelastic scattering by implementing multi-jet merging capabilities in Vincia parton shower in the general-purpose Monte Carlo event generator, Pythia. Merging allows to combine event samples of different parton multiplicities with logarithmically enhanced radiation from parton shower algorithms, without double-counting. Here we consider events up to five outgoing partons and present results for jet analyses compared to experimental data provided by the ZEUS and H1 collaborations of the HERA collider. The analyses span a wide range in photon virtuality, and the results show that the multi-jet merging improves jet modelling especially for low virtuality events.

   hep-phPoS(2025)·1 citation
7. 07*

   Bayesian Inference analysis of jet quenching using inclusive jet and hadron suppression measurements

   R. Ehlers🇺🇸 · Y. Chen🇺🇸 · J. Mulligan🇺🇸 · Y. Ji🇺🇸 · A. Kumar🇨🇦 · S. Mak🇺🇸 · P. M. Jacobs🇺🇸 · A. Majumder🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. A. Bass🇺🇸 · R. Datta🇺🇸 and 41 other authors

   The JETSCAPE Collaboration reports a new determination of the jet transport parameter $\hat{q}$ in the Quark-Gluon Plasma (QGP) using Bayesian Inference, incorporating all available inclusive hadron and jet yield suppression data measured in heavy-ion collisions at RHIC and the LHC. This multi-observable analysis extends the previously published JETSCAPE Bayesian Inference determination of $\hat{q}$, which was based solely on a selection of inclusive hadron suppression data. JETSCAPE is a modular framework incorporating detailed dynamical models of QGP formation and evolution, and jet propagation and interaction in the QGP. Virtuality-dependent partonic energy loss in the QGP is modeled as a thermalized weakly-coupled plasma, with parameters determined from Bayesian calibration using soft-sector observables. This Bayesian calibration of $\hat{q}$ utilizes Active Learning, a machine--learning approach, for efficient exploitation of computing resources. The experimental data included in this analysis span a broad range in collision energy and centrality, and in transverse momentum. In order to explore the systematic dependence of the extracted parameter posterior distributions, several different calibrations are reported, based on combined jet and hadron data; on jet or hadron data separately; and on restricted kinematic or centrality ranges of the jet and hadron data. Tension is observed in comparison of these variations, providing new insights into the physics of jet transport in the QGP and its theoretical formulation.

   hep-phnucl-exnucl-thPRC(2025)·56 citations
8. 08*

   Photon Frequency Conversion in High-$Q$ Superconducting Resonators: Axion Electrodynamics, QED & Nonlinear Meissner Radiation

   Hikaru Ueki🇺🇸 · J. A. Sauls🇺🇸

   High-Q superconducting resonators have been proposed and developed as detectors of light-by-light scattering mediated by the hypothesized axion or virtual electron-positron pairs in quantum electrodynamics - the Euler-Heisenberg (EH) interaction. Photon frequency and mode conversion is central to the scheme for detecting such rare events. Superconducting resonators are nonlinear devices. The Meissner screening currents that confine the electromagnetic fields to the vacuum region of a superconducting RF cavity are nonlinear functions of the EM field at the vacuum-superconducting interface, and as a result can generate source currents and frequency conversion of microwave photons in the cavity. In this report we consider photon frequency and mode conversion in superconducting resonators with high quality factors from Meissner currents in single and dual cavity setups proposed for axion and QED searches based on light-by-light scattering. In a single cavity with two pump modes photon frequency conversion by the Meissner screening current dominates photon generation by the EH interaction for cavities with $Q\lesssim 10^{12}$. The Meissner currents also generate background photons that limits the operation of the resonator for axion detection in three-mode, single cavity setups. We also consider the leakage of photons from pump modes into the signal mode for both axion and EH mediated light-by-light scattering. Photon frequency conversion by the EH interaction can compete with Meissner and leakage radiation in \emph{ultra-high-Q} cavities that are beyond current state of the art. Meissner radiation and leakage backgrounds can be suppressed in dual cavity setups with appropriate choices for pump and spectator modes, as well as the single-cavity setup proposed for heterodyne detection of galactic axion dark matter.

   hep-phcond-mat.supr-conPTEP(2024)·5 citations
9. 09*

   Model implementations of axion dark matter from kinetic misalignment

   Cem Eröncel🇹🇷 · Ryosuke Sato🇯🇵 · Géraldine Servant🇩🇪 · Philip Sørensen🇮🇹

   The axion kinetic misalignment mechanism (KMM) opens the possibility of explaining dark matter for almost any axion mass and decay constant that are not accessible by the standard misalignment mechanism, in particular at low values of the axion decay constant (i.e. large coupling). This is a new opportunity for most axion experiments which could be sensitive to dark matter and probe new regimes of axion cosmology. We scrutinise UV completions that lead to the KMM mechanism. These mainly rely on the early dynamics of the axion partner, the radial mode of the complex scalar field, from which the axion inherits kinetic energy. The damping of the radial-mode energy density is then a necessary ingredient. We study in detail thermal damping from interactions in the plasma. A minimal and rather natural implementation consists of a KSVZ-type model with a nearly-quadratic potential for the radial mode extended by U(1)-breaking higher-dimensional operators. Furthermore, we study Higgs portal interactions as an alternative damping mechanism and improve upon previously proposed implementations based on quartic potentials. These implementations can lead to the QCD axion being dark matter and in the reach of IAXO, while MADMAX, IAXO and ALPS II can be sensitive to a generic Axion-Like-Particle (ALP) as dark matter. Such models typically feature a kination era. We also show that ALP dark matter from KMM points to a particular realization of inflation.

   hep-phastro-ph.COJCAP(2025)·21 citations
10. 10*

    Cold Dark Matter Based on an Analogy with Superconductivity

    Guanming Liang🇺🇸 · Robert R. Caldwell (Dartmouth College)🇺🇸

    We present a novel candidate for cold dark matter consisting of condensed Cooper pairs in a theory of interacting fermions with broken chiral symmetry. Establishing the thermal history from the early radiation era to the present, the fermions are shown to behave like standard radiation at high temperatures, but then experience a critical era decaying faster than radiation, akin to freeze-out, which sets the relic abundance. Through a second-order phase transition, fermion-antifermion pairs condense and the system asymptotes toward zero temperature and pressure. By the present era, the nonrelativistic, massive condensate decays slightly faster than in the standard scenario--a unique prediction that may be tested by combined measurements of the cosmic microwave background and large scale structure. We also show that in the case of massive fermions, the phase transition is frustrated, and instead leaves a residual, long-lived source of dark energy.

    hep-phastro-ph.COPRL(2025)·5 citations
11. 11*

    Probing a nonminimal coupling through superhorizon instability and secondary gravitational waves

    Ayan Chakraborty🇮🇳 · Subhasis Maiti🇮🇳 · Debaprasad Maity🇮🇳

    In this paper, we investigate the impact of scalar fluctuations ($\chi$) non-minimally coupled to gravity, $\xi {\chi }^{2}R$, as a potential source of secondary gravitational waves (SGWs). Our study reveals that when reheating EoS $\text{wre}<1/3$ and $\xi \lesssim 1/6$ or $\text{wre}>1/3$ and $\xi \gtrsim 1/6$, the super-horizon modes of scalar field experience a \textit{Tachyonic instability} during the reheating phase. Such instability causes a substantial growth in the scalar field amplitude leading to pronounced production of SGWs in the low and intermediate-frequency ranges that are strong enough to be detected by Planck and future gravitational wave detectors. Such growth in super-horizon modes of the scalar field and associated GW production may have a significant effect on the strength of the tensor fluctuation at the Cosmic Microwave Background (CMB) scales (parametrized by $r$) and the number of relativistic degrees of freedom (parametrized by $\text{dneff}$) at the time of CMB decoupling. To prevent such overproduction, the PLANCK constraints on tensor-to-scalar ratio $r\le 0.036$ and $\text{dneff}\le 0.284$ yield a strong lower bound on $\xi$ for $\text{wre}<1/3$, and upper bound on the value of $\xi$ for $\text{wre}>1/3$. Taking into account all the observational constraints we found the value of $\xi$ should be $\gtrsim 0.02$ for $\text{wre}=0$, and $\lesssim 4.0$ for $\text{wre}\ge 1/2$ for a wide range of reheating temperature within $10^{-2}\lesssim \text{Tre}\lesssim 10^{14}$ GeV, and for a wide range of inflationary energy scales. Further, as one approaches $\text{wre}$ towards $1/3$, the value of $\xi$ remains unconstrained. Finally, we identify the parameter regions in $(\text{Tre},\xi )$ plane which can be probed by the upcoming GW experiments namely BBO, DECIGO, LISA, and ET.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·17 citations
12. 12*

    Collective behaviour in proton number fluctuations seen in $\sqrt{s_{NN}}=$ 2.4 GeV Au+Au collisions

    Ali Bazgir🇵🇱 · Maciej Rybczynski🇵🇱 · Uzair A. Shah🇵🇱 · Zbigniew Wlodarczyk🇵🇱

    At energies of a few GeV per nucleon, nuclear collisions exhibit phenomena more complex than the individualistic nucleon interactions observed at much higher energies. From recent results on proton number fluctuations in Au + Au collisions at $\sqrt{s_{NN}}=2.4$~GeV obtained by the HADES experiment at GSI, we suggest that measuring the multiplicity distributions heavy-ion collisions can be used to probe density fluctuations associated with correlation phenomena. By using the combinant analysis, one can obtain new information contained in them and otherwise unavailable, which may broaden our knowledge of the particle interactions mechanism.

    ↳ nucl-thhep-phnucl-exPLB(2024)·0 citations
13. 13*

    Self-interacting axion clouds around rotating black holes in binary systems

    Takuya Takahashi🇯🇵 · Hidetoshi Omiya🇯🇵 · Takahiro Tanaka🇯🇵

    Superradiant instability can form clouds around rotating black holes (BHs) composed of ultralight bosonic fields, such as axions. A BH with such a cloud in a binary system exhibits rich phenomena, and gravitational waves (GWs) from the BH merger provide a means to probe axions. For the first time, we study the evolution of axion clouds in a binary system during the inspiral phase, including axion self-interaction effects. When the self-interaction is significant, unlike in the negligible case, two types of clouds coexist through mode coupling. We examine the evolution of the system considering the effects of dissipation caused by both self-interaction and tidal interaction. For tidal interaction, in addition to the processes of emission to infinity and absorption by the BH, indirect emission via transitions (both resonant and off-resonant) is also considered as a second-order perturbation. Our results demonstrate that the signatures of axion self-interaction are imprinted in the modification of the GW phase. Furthermore, we find the possibility of a dynamical instability called bosenova during the binary inspiral phase.

    ↳ gr-qcastro-ph.COhep-phPRD(2024)·39 citations
14. 14*

    Dark matter cooling during early matter-domination boosts sub-earth halos

    Avik Banerjee🇮🇳 · Debtosh Chowdhury🇮🇳 · Arpan Hait🇮🇳 · Md Sariful Islam🇮🇳

    The existence of an early matter-dominated epoch prior to the Big Bang Nucleosynthesis may lead to a scenario where the thermal dark matter cools faster than plasma before the radiation-dominated era begins. In the radiation-dominated epoch, dark matter free-streams after it decouples both chemically and kinetically from the plasma. In the presence of an early matter-dominated era, chemical decoupling of the dark matter may succeed by a partial kinetic decoupling before reheating ends, depending upon the contributions of different partial wave amplitudes in the elastic scattering rate of the dark matter. We show that the s-wave scattering is sufficient to partially decouple the dark matter from the plasma, if the entropy injection during the reheating era depends on the bath temperature, while p-wave scattering leads to full decoupling in such cosmological backdrop. The decoupling of dark matter before the end of reheating causes an additional amount of cooling, reducing its free-streaming horizon compared to the usual radiation-dominated cosmology. The enhanced matter perturbations for scales entering the horizon prior to the end of reheating, combined with the reduced free-steaming horizon, increase the number density of sub-earth mass halos. The resulting boost in the dark matter annihilation signatures could offer an intriguing probe to differentiate pre-BBN non-standard cosmological epochs. We show that the free-streaming horizon of the dark matter requires to be smaller than a cut-off to ensure a boost in the sub-earth halo populations. As case studies we present two examples: one for a scalar dark matter with $s$-wave elastic scattering and the other one featuring a fermionic dark matter with $p$-wave elastic scattering. We identify regions of parameter space in both models where the dark matter kinetically decouples during reheating, amplifying small-scale structure formation.

    ↳ astro-ph.COastro-ph.HEhep-phJCAP(2025)·8 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.