Wed·Jul 10, 2024Wednesday·July 10, 2024

1. 01*

   Net-Proton Number Cumulants in Strongly and Weakly Coupled QGP

   Kiminad A. Mamo🇺🇸

   We provide a description of the QCD phase diagram across different energy regimes. Without any adjustable free parameters fitted to lattice or experimental data, we demonstrate that the net-proton number cumulant ratios from the Beam Energy Scan-I (BES-I) central ($0-5\%$) Au+Au collision experiments at RHIC, for center-of-mass energies $\sqrt{s}\ge 39\text{GeV}$, are well described by the $\text{dynamical soft-wall}$ AdS black hole model, indicating the formation of a strongly coupled quark-gluon plasma (sQGP) dominated by gluons in the large $N_c$ limit. We identify a critical point at ${\mu }_B=247\text{MeV}$ or $\sqrt{s}=16\text{GeV}$ in this model, where net-proton cumulant ratios show non-monotonic variation. However, for $\sqrt{s}<39\text{GeV}$, the recent BES-II data does not exhibit the expected variation due to the critical point, suggesting instead a transition to a nearly-cold (${\mu }_B\gg T$) weakly coupled QGP (wQGP), for $\sqrt{s}<7.7\text{GeV}$, dominated by valence quarks. This prediction can be tested by the upcoming STAR Fixed-Target experimental data.

   hep-phhep-thnucl-exnucl-th1 citation
2. 02*

   Electromagnetic and two-photon transition form factors of the pseudoscalar mesons: An algebraic model computation

   I. M. Higuera-Angulo🇲🇽 · R. J. Hernández-Pinto🇲🇽 · K. Raya🇪🇸 · A. Bashir🇲🇽

   We compute electromagnetic and two-photon transition form factors of ground-state pseudoscalar mesons: $\pi ,K,{\eta }_c,{\eta }_b$. To this end, we employ an algebraic model based upon the coupled formalism of Schwinger-Dyson and Bethe-Salpeter equations. Within this approach, the dressed quark propagator and the relevant Bethe-Salpeter amplitude encode the internal structure of the corresponding meson. Electromagnetic properties of the meson are probed via the quark-photon interaction. The algebraic model employed by us unifies the treatment of all ground-state pseudoscalar mesons. Its parameters are carefully fitted performing a global analysis of existing experimental data including the knowledge of the charge radii of the mesons studied. We then compute and predict electromagnetic and two-photon transition form factors for a wide range of probing photon momentum-squared which is of direct relevance to the experimental observations carried out thus far or planned at different hadron physics facilities such as the Thomas Jefferson National Accelerator Facility (JLab) and the forthcoming Electron-Ion Collider. We also present comparisons with other theoretical models and approaches and lattice quantum chromodynamics.

   hep-phhep-thnucl-thPRD(2024)·10 citations
3. 03*

   Vector meson's spin alignments in high energy reactions

   Jin-Hui Chen🇨🇳 · Zuo-Tang Liang🇨🇳 · Yu-Gang Ma🇨🇳 · Xin-Li Sheng🇮🇹 · Qun Wang🇨🇳

   The global spin alignment of vector mesons has been observed by the STAR collaboration at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). It provides a unique opportunity to probe the correlation between the polarized quark and antiquark in the strongly coupled quark-gluon plasma (sQGP) produced in relativistic heavy ion collisions, opening a new window to explore the properties of sQGP. In addition, spin alignments of vector mesons have also been observed in other high-energy particle collisions such as $e^{+}{e}^{-}$ annihilations at high energies where hadron production is dominated by quark fragmentation mechanism. The results obtained are quite different from those obtained in heavy ion collisions where quark coalescence/combination mechanism dominates suggesting strong dependence on hadronization mechanisms. So comprehensive studies in different hadronization processes are needed. In this article, we present a brief review of theoretical and experimental advances in the study of vector meson's spin alignments in a variety of high-energy particle collisions, with emphasis on hadronization mechanisms.

   hep-phSCPMA(2025)·39 citations
4. 04*

   Unveiling the Secrets of Vortex Neutron Decay

   Wei Kou🇨🇳 · Bing'ang Guo🇨🇳 · Xurong Chen🇨🇳

   Investigation of decay and scattering processes of particles in a vortex state offers a novel and promising approach for probing particle structure. Our study reveals distinct properties of vortex neutron decay, which deviate from those of classical plane-wave neutron decay. We present the energy-angle distributions of the final-state electron and antineutrino in unpolarized vortex neutrons, as well as angle distributions integrated over their energies. Notably, we provide theoretical calculations of the decay behavior of neutrons with varying vortex cone angles and initial energies. We propose that identifying the vortex state of the initial neutron can be achieved by analyzing the angular and energy distributions of the final-state particles, introducing new degrees of freedom for studying weak interactions and neutron decay kinematics that have been previously overlooked in particle physics. This timely investigation takes advantage of recent advancements in vortex neutron preparation and analysis, opening up new avenues for exploring the fundamental properties of matter.

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

   Lepton flavor of four-fermion operator and fermion portal dark matter

   Yuxuan He🇨🇳 · Gang Li🇨🇳 · Jia Liu🇨🇳 · Xiao-Ping Wang🇨🇳 · Xiang Zhao🇨🇳

   We study the ultraviolet realization of semileptonic four-fermion operator $O_{ledq}^{\alpha \beta 11}$ that incorporates Majorana dark matter (DM) in both lepton-flavor-conserving (LFC) and lepton-flavor-violating (LFV) scenarios at the one-loop level via box diagram, which effectively alleviates the lower bounds on the new physics scale. The interplay between the model-independent constraints on the Wilson coefficients and DM direct detection, relic density, and collider searches in the context of fermion portal DM model with two mediators is investigated. We find that both the projected future constraint on the LFC Wilson coefficient $C_{ledq}^{2211}/{\Lambda }^2<(12.3\text{TeV}{)}^{-2}$ from the measurements of neutrino non-standard interaction in the next-generation neutrino oscillation experiments, and LFV constraint $C_{ledq}^{1211}/{\Lambda }^2<{\left(2.2\times 10^3\text{TeV}\right)}^{-2}$ from ongoing charged-lepton-flavor-violation searches, provide a complementary exploration of the parameter space encompassing the DM mass and scalar mass. With the colored mediator mass typically around $2\text{TeV}$, the sensitivity of the indirect constraints on the four-fermion operator could surpass those of collider searches and DM direct detection, in scenarios where the masses of the DM and scalar are close. By ensuring the correct DM relic density, however, we obtain that the collider searches and DM direct detection are more sensitive to the electroweak scale DM and scalar compared to the indirect constraints.

   hep-phCPC(2026)·0 citations
6. 06*

   Modular Family Symmetry in Fluxed GUTs

   Vasileios Basiouris🇬🇷 · Miguel Crispim Romão🇬🇧 · Stephen F. King🇬🇧 · George K. Leontaris🇬🇷

   We discuss modular family symmetry in effective theories based on generic properties of bottom-up local F-theory inspired GUTs broken by fluxes, which we refer to as Fluxed GUTs. We argue that the Yukawa couplings will depend on the complex structure moduli of the matter curves in such a way that they can be modular forms associated with these symmetries. To illustrate the approach we analyse in detail a concrete local fluxed $SU(5)$ GUT with modular $S_4$ family symmetry.

   hep-phhep-thPRD(2025)·4 citations
7. 07*

   Higgs-like field interactions before symmetry breaking

   Jerzy Paczos🇮🇹 · Szymon Cedrowski🇵🇱 · Krzysztof Turzyński🇵🇱 · Andrzej Dragan🇵🇱

   We investigate the Brout-Englert-Higgs mechanism of spontaneous symmetry breaking and show that, before symmetry breaking, the interaction of Higgs fields with massless gauge fields leads to the production of particles with negative squared mass.

   hep-phgr-qcNPB(2026)·3 citations
8. 08*

   Deep-Inelastic Scattering with LHC Neutrinos

   Juan Rojo🇳🇱

   The observation of neutrinos produced in LHC collisions by the far-forward FASER and SND@LHC experiments in 2023 herald the new era of collider neutrino physics. These high-intensity forward neutrino fluxes from proton-proton LHC collisions enable novel opportunities in QCD, neutrino physics, BSM searches, and astroparticle physics. In this contribution, we briefly review the physics potential of neutrino deep-inelastic scattering (DIS) measurements at the LHC to shed light on proton and nuclear structure, both for ongoing far-forward experiments and for the proposed Forward Physics Facility (FPF) to operate concurrently with the HL-LHC. We consider the reach of LHC neutrino DIS to scrutinise the mechanisms of forward hadron production and constrain QCD in the ultra-small-$x$ region. We also discuss how neutrino DIS measurements at these far-forward detectors enhance direct and indirect BSM searches at the HL-LHC.

   hep-phPoS(2025)·8 citations
9. 09*

   Multipartite dark matter in a gauge theory of leptons

   Utkarsh Patel🇮🇳 · Avnish🇮🇳 · Sudhanwa Patra🇮🇳 · Kirtiman Ghosh🇮🇳

   The classical conservation of the lepton number is an accidental symmetry present in the Standard Model (SM). Thus, we consider here a scenario where the SM is extended with a U(1) gauge group, promoting the lepton number to a local symmetry. The gauge anomaly cancellations necessitate the extension of the particle spectrum with several beyond the SM (BSM) particle fields. The extended lepton gauge group breaks around the TeV scale via spontaneous symmetry breaking, and a $Z_2$ symmetry remains, which ensures the stability of the light $Z_2$ odd BSM particles. Interestingly, the particle spectrum of the model has two distinct dark sectors, with one having a Dirac-type DM and the other one containing a Majorana-type DM, thus resulting in a multipartite dark matter scenario. We have explored the available parameter space consistent with the observed dark matter relic density and direct detection measurements for both of the DM particles. Having a Majorana dark matter, we have also studied for the gamma line signatures to constrain the parameter space from the indirect dark matter detection experiments like FermiLAT and CTA.

   hep-phhep-thJHEP(2025)·4 citations
10. 10*

    Charged current weak production of $\Delta (1232)$ induced by electrons and positrons

    A. Fatima🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳

    The charged current weak production of $\Delta (1232)$ from the free proton target induced by the electron/positron in the intermediate energy range corresponding to the beam energy available at JLab and Mainz, has been studied. The results for the differential scattering cross section $\frac{d\sigma }{d{Q}^2}$, the angular distribution $\frac{d\sigma }{d{\Omega }_{\Delta }}$, and the total scattering cross section $\sigma (E_e)$ for both the electron and positron induced processes are presented, for the various energies in the range of 0.5--4~GeV. The cross section $\sigma (E_e)$ is found to be of the order of $10^{-39}$~cm${}^2$ for the electron/positron energies in the few GeV range. The availability of electron/positron beams having well defined energy and direction with very high luminosity of the order of $10^{38}-10^{39}$~cm${}^{-2}$~sec${}^{-1}$, makes it possible to observe the weak charged current production of $\Delta (1232)$ and determine the axial vector form factors $C_i^A(Q^2);(i=3-5)$. The sensitivity of the differential cross section $\frac{d\sigma }{d{Q}^2}$ to the subdominant form factors $C_3^A(Q^2)$ and $C_4^A(Q^2)$ is found to be strong enough, especially in the low $Q^2$ region, which can be used to determine them phenomenologically and to test the various theoretical models proposed to calculate them.

    hep-phhep-exnucl-thPRD(2024)·3 citations
11. 11*

    Searching Accretion-Enhanced Dark Matter Annihilation Signals in the Galactic Centre

    MeiWen Yang🇨🇳 · Zhi-Qi Guo🇨🇳 · Xiao-Yi Luo🇨🇳 · Zhao-Qiang Shen🇨🇳 · Zi-Qing Xia🇨🇳 · Chih-Ting Lu🇨🇳 · Yue-Lin Sming Tsai🇨🇳 · Yi-Zhong Fan🇨🇳

    This study reanalyzes the detection prospects of dark matter (DM) annihilation signals in the Galactic Center, focusing on velocity-dependent dynamics within a spike density near the supermassive black hole (Sgr~A${}^{\star }$). We investigate three annihilation processes -- $p$-wave, resonance, and forbidden annihilation -- under semi-relativistic velocities, leveraging gamma-ray data from Fermi and DAMPE telescopes. Our analysis integrates a fermionic DM model with an electroweak axion-like particle (ALP) portal, exploring annihilation into two or four photons. Employing a comprehensive six-dimensional integration, we precisely calculate DM-induced gamma-ray fluxes near Sgr~A${}^{\star }$, incorporating velocity and positional dependencies in the annihilation cross-section and photon yield spectra. Our findings highlight scenarios of resonance and forbidden annihilation, where the larger ALP-DM-DM coupling constant $C_{a\chi \chi }$ can affect spike density, potentially yielding detectable gamma-ray line spectra within Fermi and DAMPE energy resolution. We set upper limits for $C_{a\chi \chi }$ across these scenarios, offering insights into the detectability and spectral characteristics of DM annihilation signals from the Galactic Center.

    hep-phastro-ph.HEJHEP(2024)·12 citations
12. 12*

    Evaluating Parametric Integrals in the Minkowski Regime without Contour Deformation

    Stephen Jones🇬🇧 · Anton Olsson🇩🇪 · Thomas Stone🇬🇧

    We present selected examples demonstrating an alternative approach to contour deformation for numerically computing loop integrals in the Minkowski regime. This method focuses on identifying singular hypersurfaces (varieties of the $\mathcal{F}$ polynomial) and mapping them to known points which can then be resolved by employing blow-ups/sector decomposition techniques, thereby avoiding the need for contour deformation. Using this technique, we achieve improved convergence properties without the need for contour deformation, which is known to significantly increase the complexity of the integrand by introducing, for example, derivatives of the $\mathcal{F}$ polynomial and complicated Jacobians. We highlight that while we have only tested the approach on selected one-, two- and three-loop massless and one-loop massive examples, it shows promise for practical applications, offering potential benefits over the traditional approach. Evaluation times are compared with existing contour deformation implementations to illustrate the performance of this alternative method.

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

    Curved-spacetime dynamics of spin-$\frac{1}{2}$ particles in superposed states from a WKB approximation of the Dirac equation

    F. Hammad🇨🇦 · M. Simard🇨🇦 · R. Saadati🇨🇦 · A. Landry🇨🇦

    We investigate the dynamics of spin-$\frac{1}{2}$ particles that are freely propagating in superposed states in curved spacetime. We first make use of a Wentzel-Kramers-Brillouin approximation of the Dirac equation in curved spacetime to extract the corresponding Mathisson-Papapetrou-Dixon equations that describe the deviation from geodesic motion as well as the spin precession of such particles. We then discuss, in light of our results, the case of flavour neutrinos which are, by nature, a superposition of mass eigenstates.

    hep-phgr-qcPRD(2024)·8 citations
14. 14*

    Nuclear Spin Metrology with Nitrogen Vacancy Center in Diamond for Axion Dark Matter Detection

    So Chigusa🇺🇸 · Masashi Hazumi🇯🇵 · Ernst David Herbschleb🇯🇵 · Yuichiro Matsuzaki🇰🇷 · Norikazu Mizuochi🇯🇵 · Kazunori Nakayama🇯🇵

    We present a method to directly detect the axion dark matter using nitrogen vacancy centers in diamonds. In particular, we use metrology leveraging the nuclear spin of nitrogen to detect axion-nucleus couplings. This is achieved through protocols designed for dark matter searches, which introduce a novel approach of quantum sensing techniques based on the nitrogen vacancy center. Although the coupling strength of the magnetic fields with nuclear spins is three orders of magnitude smaller than that with electron spins for conventional magnetometry, the axion interaction strength with nuclear spins is the same order of magnitude as that with electron spins. Furthermore, we can take advantage of the long coherence time by using the nuclear spins for the axion dark matter detection. We show that our method is sensitive to a broad frequency range $\lesssim 100\mathrm{Hz}$ corresponding to the axion mass $m_a\lesssim 4\times 10^{-13}\mathrm{eV}$. We present the detection limit of our method for both the axion-neutron and the axion-proton couplings and discuss its significance in comparison with other proposed ideas.

    hep-phcond-mat.mes-hallhep-exquant-phPRD(2025)·17 citations
15. 15*

    LANSCE-mQ: Dedicated search for milli/fractionally charged particles at LANL

    Yu-Dai Tsai🇺🇸 · Insung Hwang🇰🇷 · Ryan Schmitz🇺🇸 · Matthew Citron🇺🇸 · Kranti Gunthoti🇺🇸 · Jacob Steenis🇺🇸 · Hoyong Jeong🇰🇷 · Hyunki Moon🇰🇷 · Jae Hyeok Yoo🇰🇷 · Ming Xiong Liu🇺🇸

    In this paper, we propose an experiment, LANSCE-mQ, aiming to detect fractionally charged and millicharged particles (mCP) using an 800 MeV proton beam fixed target at the Los Alamos Neutron Science Center (LANSCE) facility. This search can shed new light on numerous fundamental questions, including charge quantization, the predictions of string theories and grand unification theories, the gauge symmetry of the Standard Model, dark sector models, and the tests of cosmic reheating. We propose to install two-layer scintillation detectors made of plastic (such as EJ-200) or CeBr3 to search for mCPs. Dedicated Geant4 detector simulations and in situ measurements have been conducted to obtain a preliminary determination of the background rate. The dominant backgrounds are beam-induced neutrons and coincident dark current signals from the photomultiplier tubes, while beam-induced gammas and cosmic muons are subdominant. We determined that LANSCE-mQ, the dedicated mCP experiment, has the leading mCP sensitivity for mass between ~ 1 MeV to 300 MeV.

    hep-phastro-ph.COhep-exhep-thPRD(2026)·11 citations
16. 16*

    Analytical Insights on Hadronic Top Quark Polarimetry

    Zhongtian Dong🇺🇸 · Dorival Gonçalves🇺🇸 · Kyoungchul Kong🇺🇸 · Andrew J. Larkoski🇺🇸 · Alberto Navarro🇺🇸

    Top quark polarization provides an important tool for studying its production mechanisms, spin correlations, top quark properties, and new physics searches. Unlike lighter quarks, the top quark's polarization remains intact until its decay, enabling precise spin measurements. While the down-type fermions from $W$ boson decay are known to be effective spin analyzers, charged leptons have typically been the main target for most analyses. In this paper, we investigate the relevance of global jet dynamics -- considering kinematics, jet charges, and particle multiplicity -- for hadronic top quark polarimetry. The formalism used allows for analytical derivations obtained throughout the manuscript, offering deeper insights into the corresponding phenomenology.

    hep-phhep-exJHEP(2025)·10 citations
17. 17*

    Reducing Complex Phases and other Subtleties of CP Violation

    José Filipe Bastos🇵🇹 · J.I. Silva-Marcos🇵🇹

    When extending the SM, e.g. with vector-like quarks (VLQ), one inevitably encounters more than one CP violating complex phases. In this work, we develop a method useful in reducing the number of complex phases in scenarios with one and two VLQs. We show that these VLQ-models can be described with just one or two physical complex phases respectively and present an explicit alternative parametrization for the quark mixing matrix. Making use of this Reduction of Complex Phases in the case of the Bento-Branco-Parada (BBP) model, i.e. the simplest implementation of the Nelson-Barr solution to the strong CP problem, one also recovers the single phase formulation of BBP model. We comment on how this specific scenario can be distinguished from the general VLQ case with weak-basis invariants

    hep-ph4 citations
18. 18*

    Analysis of the hidden-charm-hidden-strange tetraquark mass spectrum via the QCD sum rules

    Zhi-Gang Wang🇨🇳

    In the present work, we construct the diquark-antidiquark type four-quark currents to investigate the mass spectrum of the ground state hidden-charm-hidden-strange tetraquark states with the quantum numbers $J^{PC}=0^{++}$, $1^{+-}$, $1^{++}$ and $2^{++}$ via the traditional QCD sum rules in a comprehensive way. We update old calculations, perform new calculations and analysis in a rigorous way, and take account of the net light-flavor $SU(3)$ breaking effects in a consistent way. And we make more reasonable identifications for the $X(3960)$, $X(4140)$, $X(4274)$, $X(4500)$, $X(4685)$ and $X(4700)$ and supersede some old identifications. Furthermore, we consider our previous theoretical predictions, and make reasonable/suitable identifications of the new LHCb states $h_c(4000)$ and ${\chi }_{c1}(4010)$.

    hep-phNPB(2024)·18 citations
19. 19*

    Higher-Dimensional MOG dark compact object: shadow behavior in the light of EHT observations

    Kourosh Nozari🇮🇷 · Sara Saghafi🇮🇷 · Ali Mohammadpour🇮🇷

    Consideration of extra spatial dimensions is motivated by the unification of gravity with other interactions, the achievement of the ultimate framework of quantum gravity, and fundamental problems in particle physics and cosmology. Much attention has been focused on the effect of these extra dimensions on the modified theories of gravity. Analytically examining astrophysical phenomena like black hole shadows is one approach to understand how extra dimensions would affect the modified gravitational theories. The purpose of this study is to derive a higher dimensional metric for a dark compact object in STVG theory and then examine the behavior of the shadow shapes for this solution in STVG theory in higher dimensions. We apply the Carter method to formulate the geodesic equations and the Hamilton Jacobi method to find photon orbits around this higher dimensional MOG dark compact object. We investigate the effects of extra dimensions and the STVG parameter alpha on the black hole shadow size. Next, we compare the shadow radius of this higher dimensional MOG dark compact object to the shadow size of the supermassive black hole M87, which has been realized by the Event Horizon Telescope (EHT) collaborations, in order to restrict these parameters. We find that extra dimensions in the STVG theory typically lead to a reduction in the shadow size of the higher dimensional MOG dark compact object, whereas the effect of parameter alpha on this black hole shadow is suppressible. Remarkably, given the constraints from EHT observations, we find that the shadow size of the four dimensional MOG dark compact object lies in the confidence levels of the EHT data. Finally, we investigate the issue of acceleration bounds in higher dimensional MOG dark compact object in confrontation with EHT data of M87.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2024)·22 citations
20. 20*

    Electron scattering cross section for light nuclei within the unified electroweak theory

    Vo Minh Truong · Nguyen Quang Hung

    We employ the multipole expansion within the unified electroweak theory to develop a complete calculation method of the electron scattering cross section for light nuclei. The specific calculations for 6,7Li and 7Be nuclei indicate that the conventional impulse approximation can be applied to the electron-nucleus scattering only when the incident electron energy does not exceed twice the nucleon mass. In addition, the quasi-elastic scattering cross section of 7Li in the excitation from its ground state to the nearest excited state and that of elastic scattering in the ground state are independently treated, whereas they have not been separately measured in experiments. The obtained scattering cross sections corresponding to an appropriate adjustment of the harmonic oscillator parameter along with the V-A structure interpret reasonably well the available experimental data at MeV energies and provide predictive information at GeV energies. This gives new perspectives in studying the structure of nuclei and the weak interactions via electron or lepton scattering at high (GeV) energies, considering nuclei rather than quarks.

    ↳ nucl-thhep-phPRC(2024)·0 citations
21. 21*

    Generation of effective massive Spin-2 fields through spontaneous symmetry breaking of scalar field

    Susobhan Mandal🇮🇳 · S. Shankaranarayanan (IIT Bombay)🇮🇳

    General relativity and quantum field theory are the cornerstones of our understanding of physical processes, from subatomic to cosmic scales. While both theories work remarkably well in their tested domains, they show minimal overlap. However, our research challenges this separation by revealing that non-perturbative effects bridge these distinct domains. We introduce a novel mechanism wherein, at linear order, spin-2 fields around an arbitrary background acquire \emph{effective mass} due to the spontaneous symmetry breaking (SSB) of either global or local symmetry of complex scalar field minimally coupled to gravity. The action of the spin-2 field is identical to the extended Fierz-Pauli (FP) action, corresponding to the mass deformation parameter $\alpha =1/2$. We show that this occurs due to the effect of SSB on the variation of the energy-momentum tensor of the matter field, which has a dominant effect during SSB. The extended FP action has a salient feature, compared to the standard FP action: the action has 6 degrees of freedom with no ghosts. For local $U(1)$ SSB, we establish that the effective mass of spin-2 fields is related to the mass of the gauge boson and the electric charge of the complex scalar field. Interestingly, our results indicate that the millicharged dark matter scalar fields, generating dark photons, can produce a mass of spin-2 fields of the same order as the Hubble constant $(H_0)$. Hence, we argue that the dark sector offers a natural explanation for the acceleration of the current Universe.

    ↳ hep-thastro-ph.COgr-qchep-phGen.Rel.Grav.(2025)·3 citations
22. 22*

    QCD with (2+1) flavors at the physical point in external chromomagnetic fields

    Paolo Cea🇮🇹 · Leonardo Cosmai🇮🇹

    We investigate full QCD with (2+1)-flavour of HISQ fermions at the physical point in the presence of uniform Abelian chromomagnetic background fields. Our focus is on the renormalized light and strange chiral condensate around the pseudo-critical temperature. We find that in the confined region the gauge system is subjected to the chromomagnetic catalysis that turns into the inverse catalysis in the high-temperature regime. We further observe that the chiral condensates are subjected to the so-called thermal hysteresis. Our estimate of the deconfinement temperature indicates that the critical temperature begins to decrease in the small field region, soon after it seems to saturate and finally increase with the strength of the chromomagnetic field.

    ↳ hep-lathep-exhep-phPRD(2024)·1 citation
23. 23*

    A Method to Constrain Preferential Emission and Spectator Dynamics in Heavy-Ion Collisions

    Vipul Bairathi🇨🇱 · Somadutta Bhatta🇺🇸

    Longitudinal particle production in heavy-ion collisions is influenced both by preferential emission from participating nucleons and by the breakup of spectator matter, yet quantifying these effects experimentally remains challenging. We introduce a Pearson correlation between spectator and charged-particle forward-backward asymmetries as an experimental probe of these phenomena. Using Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV simulated with A Multi-Phase Transport (AMPT) model, we validate that this correlator provides a robust, pseudorapidity-differential measure of the influence of preferential emission on the longitudinal structure of particle production. We further demonstrate that the correlation strength is sensitive to fluctuations in spectator number, which in experiments arise from evaporation and fragmentation of the spectator remnants. The proposed observable therefore offers a data-driven handle for constraining models of preferential emission and spectator breakup, thereby improving our understanding of the mechanisms that shape the final-state longitudinal distributions in heavy-ion collisions.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2026)·0 citations
24. 24*

    Enhanced ${\psi }^{\prime }$ yield and ${\psi }^{\prime }/(J/\psi )$ yield ratio as a possible signature of QGP formation in high multiplicity $p+p$ collisions

    Partha Bagchi🇮🇳 · Arpan Das🇮🇳 · Ananta P. Mishra🇮🇳 · Ankit Kumar Panda🇮🇳

    Suppression in the yield of quarkonia (heavy quark-antiquark bound states) has been considered one of the important signatures of the formation of the thermalized deconfined partonic matter, also known as the Quark Gluon Plasma (QGP), in Relativistic Heavy Ion Collision Experiments (RHICE). Traditionally, the in-medium dissociation of quarkonium states has been presented by implicitly assuming an adiabatic approximation, which considers that the heavy quark Hamiltonian changes slowly over time owing to change in the medium. However, in high multiplicity smaller systems, such as in $p+p$ collisions, the early development of transverse flow resulting from the finite transverse size of the locally thermalized medium may cause the quarkonium states to undergo a non-adiabatic evolution. It has been argued that in the presence of such a non-adiabatic evolution, the suppression of heavy quark-antiquark bound state yields may not reliably indicate QGP formation~\cite{Bagchi:2023vfv}. We propose that, rather than concentrating on the suppression of $J/\psi$ yields, the enhancement in the yield ratio of ${\psi }^{\prime }$ to $J/\psi$ (i.e., ${\psi }^{\prime }/(J/\psi )$), along with an increase in ${\psi }^{\prime }$ yield, should be considered as a probe of QGP formation for small systems. Our findings, based on realistic modeling of the time evolution of small systems, suggest that the yield ratio ${\psi }^{\prime }/(J/\psi )$ and the yield of ${\psi }^{\prime }$ increase as a function of hydrodynamization temperature incorporating the non-adiabatic transitions in high multiplicity $p+p$ collisions.

    ↳ nucl-thhep-ph1 citation
25. 25*

    QCD Axion Dark Matter in String Theory: Haloscopes and Helioscopes as Probes of the Landscape

    Naomi Gendler🇺🇸 · David J. E. Marsh🇬🇧

    Laboratory experiments have the capacity to detect the QCD axion in the next decade, and precisely measure its mass, if it composes the majority of the dark matter. In type IIB string theory on Calabi-Yau threefolds in the geometric regime, the QCD axion mass, $m_a$, is strongly correlated with the topological Hodge number $h^{1,1}$. We compute $m_a$ in a scan of $185,965$ compactifications of type IIB string theory on toric hypersurface Calabi-Yau threefolds. We compute the range of $h^{1,1}$ probed by different experiments under the condition that the QCD axion can provide the observed dark matter density with minimal fine-tuning. Taking the experiments DMRadio, ADMX, MADMAX, and BREAD as indicative on different mass ranges, the $h^{1,1}$ distributions peak near $h^{1,1}=24.9,65.4,196.8,$ and $310.9,$ respectively. We furthermore conclude that, without severe fine tuning, detection of the QCD axion as dark matter \emph{at any mass} disfavours 80% of models with $h^{1,1}=491$, which is thought to have the most known Calabi-Yau threefolds. Measurement of the solar axion mass with IAXO is the dominant probe of all models with $h^{1,1}\gtrsim 250$. This study demonstrates the immense importance of axion detection in experimentally constraining the string landscape.

    ↳ hep-thhep-phPRL(2025)·25 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.