Fri·Aug 30, 2024Friday·August 30, 2024

1. 01*

   Effective interactions and on-shell recursion relation for massive spin 3/2

   Tony Gherghetta🇺🇸 · Wenqi Ke🇺🇸

   We use on-shell methods to compute all three-point interactions of massive spin-3/2 particles involving a graviton and particles of spin $\le 1$. By employing the massive spinor-helicity formalism we identify the interactions which have a smooth massless limit as expected from the superHiggs mechanism. These interactions are then used to on-shell construct four-point massive spin-3/2 amplitudes using an all-line transverse shift for the external momenta, which correctly reproduces the contact gravitino interactions in the $N=1$ supergravity Lagrangian. The on-shell constructed four-point amplitudes are also used to derive well-known unitarity bounds in supergravity. In particular, by adding scalar and pseudoscalar interactions to construct the four-point massive spin-3/2 amplitudes that scale as $E^2$ in the high-energy limit, we recover the on-shell Polonyi model with a Planck scale unitarity bound. These effective three-point interactions and on-shell recursion relations provide an alternative and simpler way to study the interactions of massive spin-3/2 particles without a Lagrangian or the use of Feynman diagrams.

   hep-phhep-thJHEP(2025)·10 citations
2. 02*

   Improved Treatment of Bosonic Dark Matter Dynamics in Neutron Stars: Consequences and Constraints

   Koushik Dutta🇮🇳 · Deep Ghosh🇮🇳 · Biswarup Mukhopadhyaya🇮🇳

   It is conceivable that a bosonic dark matter (DM) with non-gravitational interactions with SM particles will be accumulated at the center of a neutron star (NS) and can lead to black hole formation. In contrast to previous works with a fixed NS temperature, we dynamically determine the formation of Bose-Einstein condensate (BEC) for a given set of DM parameters, namely the DM-neutron scattering cross-section (${\sigma }_{\chi n}$), the thermal average of DM annihilation cross-section ($⟨\sigma v⟩$) and the DM mass ($m_{\chi }$). For both non-annihilating and annihilating DM with $⟨\sigma v⟩\lesssim 10^{-26}\mathrm{c}{\mathrm{m}}^3{\mathrm{s}}^{-1}$, the BEC forms for $m_{\chi }\lesssim 10$ TeV. In case of non-annihilating DM, observations of old NS allows ${\sigma }_{\chi n}\lesssim 10^{-52}\mathrm{c}{\mathrm{m}}^2$ for $10\mathrm{MeV}\le m_{\chi }\lesssim 10\mathrm{GeV}$ (with BEC) and ${\sigma }_{\chi n}\lesssim 10^{-47}\mathrm{c}{\mathrm{m}}^2$ for $5\mathrm{TeV}\lesssim m_{\chi }\lesssim 30\mathrm{PeV}$ (without BEC). This analysis shows that the electroweak mass window, $10\mathrm{GeV}\lesssim m_{\chi }\lesssim 5\mathrm{TeV}$ is essentially unconstrained by NS observations and therefore is subject only to direct detection experiments. In the annihilating DM scenario, the exclusion limits on DM parameters become weaker and even vanish for typical WIMP annihilation cross-section. However, the late-time heating of the NS enables us to probe the region with ${\sigma }_{\chi n}\gtrsim 10^{-47}\mathrm{c}{\mathrm{m}}^2$, using the James Webb Space Telescope in the foreseeable future. When our results are viewed in the context of indirect searches of DM, it provides a lower limit on the $⟨\sigma v⟩$, which is sensitive to the DM thermal state.

   hep-phJCAP(2024)·8 citations
3. 03*

   Constraints on $\tau$ electromagnetic moments via tau pair production at the Muon colliders

   H. Denizli🇹🇷 · A. Senol🇹🇷 · M. Köksal🇹🇷

   The anomalous magnetic (${\tilde{a}}_{\tau }$) and electric dipole (${\tilde{d}}_{\tau }$) moment of tau lepton described in $\tau \bar{\tau }\gamma$ vertices are studied via ${\mu }^{+}{\mu }^{-}\to {\tau }^{+}{\bar{\tau }}^{-}$ process at the Muon colliders designed with the proposed center-of-mass-energy / integrated luminosity configurations of 3 TeV/ 1 ab${}^{-1}$ and 10 TeV/ 10 ab${}^{-1}$.We obtained the $95\%$ confidence level limits on the ${\tilde{a}}_{\tau }$ and ${\tilde{d}}_{\tau }$ parameters without and with systematic uncertainty of $10\%$ and compared with the experimental results.The most stringent limits on the anomalous couplings without systematic uncertainty are $-2.63\times 10^{-4}<{\tilde{a}}_{\tau }<2.65\times 10^{-4}$ and $\mid {\tilde{d}}_{\tau }\mid \le 1.47\times 10^{-18}ecm$ at $\sqrt{s}=10$ TeV and $L_{int}$=10 ab${}^{-1}$ option of the Muon collider. Our results show that the Muon colliders lead to a remarkable improvement on the current experimental limits of the anomalous magnetic and electric dipole moments of the tau lepton.

   hep-phChin.J.Phys.(2025)·7 citations
4. 04*

   The Standard Model of Particle Physics as an effective theory from two non-universal $U(1)$'s

   Richard H. Benavides🇨🇴 · Yithsbey Giraldo🇨🇴 · William A. Ponce🇨🇴 · Oscar Rodríguez🇨🇴 · Eduardo Rojas🇨🇴

   We study the possibility of obtaining the Standard Model (SM) of particle physics as an effective theory of a more fundamental one, whose electroweak sector includes two non-universal local $U(1)$ gauge groups, with the chiral anomaly cancellation taking place through an interplay among families. As a result of the spontaneous symmetry breaking, a massive gauge boson $Z^{\prime }$ arises, which couples differently to the third family of fermions (by assumption, we restrict ourselves to the scenario in which the $Z^{\prime }$ couples in the same way to the first two families). Two Higgs doublets and one scalar singlet are necessary to generate the SM fermion masses and break the gauge symmetries. We show that in our model, the flavor-changing neutral currents (FCNC) of the Higgs sector are identically zero if each right-handed SM fermion is only coupled with a single Higgs doublet. This result represents a FCNC cancellation mechanism different from the usual procedure in Two-Higgs Doublet Models~(2HDM). The non-universal nature of our solutions requires the presence of three right-handed neutrino fields, one for each family. Our model generates all elements of the Dirac mass matrix for quarks and leptons, which is quite non-trivial for non-universal models. Thus, we can fit all the masses and mixing angles with two scalar doublets. Finally, we show the distribution of solutions for the scalar boson masses in our model by scanning well-motivated intervals for the model parameters. We consider two possibilities for the scalar potential and compare these results with the Higgs-like resonant signals recently reported by the ATLAS and CMS experiments at the LHC. Finally, we also report collider, electroweak, and flavor constraints on the model parameters.

   hep-phJ.Phys.G(2025)·0 citations
5. 05*

   Future targets for light gauge bosons from cosmic strings

   Hanyu Cheng🇨🇳 · Luca Visinelli🇨🇳

   Cosmic strings, theoretical one-dimensional topological defects from the early universe, provide a valuable opportunity for exploring dark matter (DM) production and gravitational wave (GW) emission. Our study investigates the production of gauge bosons and GW emission from cosmic string decay, considering the constraints imposed by cosmological observations. We specifically examine how gauge bosons radiated from strings contribute to DM and dark radiation, with limits set by the observed DM abundance and cosmic microwave background data, respectively. Additionally, we analyze the gravitational wave spectrum of this model across both low and high frequencies. Notably, the spectrum typically follows a $f^{-1/3}$ pattern at high frequencies, beyond the pivot frequency $f_{\ast }$. We derive an analytical expression for the frequency $f_{\ast }$ and confirm its accuracy through numerical verification. Furthermore, we compare the GW spectrum of this model with the forecasted capabilities of future GW observatories, such as the Einstein Telescope, the Laser Interferometer Space Antenna, the Big Bang Observer, and $\mu$Ares. Finally, we discuss how these considerations impact the model parameters, specifically the gauge boson mass and the energy scale of U(1) symmetry breaking, providing insights into how cosmic strings could enhance our understanding of DM and GW astronomy.

   hep-phastro-ph.COhep-thPhys.Dark Univ.(2024)·9 citations
6. 06*

   Analysis of the semileptonic $B_c\to D_s^{\ast }{\mu }^{+}{\mu }^{-}$ decay mode in the effective field theory approach

   Ajay Kumar Yadav🇮🇳 · Manas Kumar Mohapatra🇮🇳 · Suchismita Sahoo🇮🇳

   Discrepancies have been noted between experimental measurements and Standard Model predictions for various observables related to the $B\to (K,K^{\ast },\varphi )ll$ processes. Recently, the Belle-II Collaboration observed a $2.8\sigma$ deviation from Standard Model predictions in the branching ratio of the $B\to K{\nu }_l\overline{{\nu }_l}$ decay mode. In this context, we investigate the exclusive semileptonic $B_c\to D_s^{\ast }{\mu }^{+}{\mu }^{-}$ decay mode, mediated by $b\to s$ quark level transition, using Effective Field Theory formalism. We perform a global fit to the new parameters using existing experimental data on $b\to s{\mu }^{+}{\mu }^{-}$. We then estimate the branching ratio and other observables such as forward-backward asymmetry, lepton polarisation asymmetry, and the lepton non-universality parameter of the $B_c\to D_s^{(\ast )}{\mu }^{+}{\mu }^{-}$ process. Although this process has not yet been detected experimentally, we offer predictions and discuss the observables for $B_c\to D_s^{\ast }{\mu }^{+}{\mu }^{-}$ in both the Standard Model and potential new physics scenarios.

   hep-phEPJ Web Conf.(2024)·2 citations
7. 07*

   Event-activity-dependent beauty-baryon enhancement in simulations with color junctions

   Lea Virág Földvári🇭🇺 · Zoltán Varga🇭🇺 · Róbert Vértesi🇭🇺

   Recent results from ALICE and CMS show a low-transverse-momentum enhancement of charm baryon-to-meson production ratios over model predictions based on e${}^{+}$e${}^{-}$ collisions. Several mechanisms are proposed to understand this phenomenon. New measurements by the LHCb and ALICE experiments show a similar enhancement in the beauty sector. We explore this enhancement in terms of event activity using the color-reconnection beyond leading order approximation model. We propose sensitive probes relying on the event shape that will allow for the differentiation between the proposed beauty-production scenarios using freshly collected LHC Run-3 data, and we also compare these to predictions for charm. Our results will contribute to a deeper theoretical understanding of the heavy-flavor baryon enhancement and its relation to baryon enhancement in general.

   hep-phnucl-exInt.J.Mod.Phys.A(2025)·0 citations
8. 08*

   Gravitational waves from thermal heavy scalar dark matter

   Parsa Ghorbani🇮🇷

   We propose a gauge singlet scalar with mass around 1-100 TeV as a thermal heavy dark matter candidate along with a dilaton as a Higgs portal mediator in a dimensionless scalar extension of the Standard Model. We demonstrate analytically that such a model gives rise to very strong first-order electroweak phase transition through supercooling. We calculate the corresponding gravitational wave signals due to bubble collisions during the phase transition. The produced gravitational waves can be detected by future space-based gravitational wave detectors in the frequency range from 10^{-4} Hz to 0.1 Hz.

   hep-phastro-ph.HEgr-qchep-thPRD(2024)·8 citations
9. 09*

   Electromagnetic responses of a non-extensive quark-gluon plasma

   Bing-feng Jiang🇨🇳 · Jun Chen🇨🇳 · De-fu Hou🇨🇳

   Based on the non-extensive statistical mechanics and the gluon polarization tensor obtained from kinetic theory, we derive the longitudinal and transverse gluon self-energies for the quark-gluon plasma. The electric permittivity $\epsilon$ and the magnetic permeability ${\mu }_M$ are evaluated from the gluon self-energies through which the real part of the square of the refraction index $\mathrm{Re}{n}^2$ and the Depine-Lakhtakia index $n_{DL}$ are investigated. The real part of $\epsilon$ displays a frequency pole ${\omega }_d=p$, which is just the position of the frequency inflexion of the imaginary part of $\epsilon$. The non-extensive parameter $q$ significantly affects the real and imaginary parts of $\epsilon$ in the space-like region $\omega <p$, while the frequency pole ${\omega }_d=p$ remains unchanged as $q$ increases. The magnetic permeability, $\mathrm{Re}{n}^2$ and the Depine-Lakhtakia index $n_{DL}$ diverge at frequency ${\omega }_m$. As $q$ increases, the pole frequency ${\omega }_m$ shifts to large frequency region. The Depine-Lakhtakia index $n_{DL}$ becomes negative in a quite large frequency region $\omega \in [{\omega }_c,{\omega }_m]$. When $q$ increases, the frequency range for $n_{DL}<0$ becomes wider. Nevertheless, there are no propagating modes for the negative refraction. In addition, as momentum $p$ increases, the electric permittivity, the magnetic permeability, $\mathrm{Re}{n}^2$ and $n_{DL}$ are sensitive to the change of $p$, which indicates the importance of the spatial dispersion in the electromagnetic responses of the QGP.

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

    On the Schwinger effect during axion inflation

    Richard von Eckardstein🇩🇪 · Kai Schmitz🇩🇪 · Oleksandr Sobol🇩🇪

    Pair-creation of charged particles in a strong gauge-field background - the renowned Schwinger effect - can strongly alter the efficiency of gauge-field production during axion inflation. It is therefore crucial to have a clear understanding and proper description of this phenomenon to obtain reliable predictions for the physical observables in this model. In the present work, we revisit the problem of Schwinger pair production during axion inflation in the presence of both electric and magnetic fields and improve on the state of the art in two ways: (i) taking into account that the electric- and magnetic-field three-vectors are in general not collinear, we derive the vector decomposition of the Schwinger-induced current in terms of these fields and determine the corresponding effective electric and magnetic conductivities; (ii) by identifying the physical momentum scale associated with the pair-creation process, we incorporate Schwinger damping of the gauge field in a scale-dependent fashion in the relevant equations of motion. Implementing this new description in the framework of the gradient-expansion formalism, we obtain numerical results in a benchmark scenario of axion inflation and perform a comprehensive comparison with earlier results in the literature. In some cases, the resulting energy densities of the produced gauge fields differ from the old results by more than one order of magnitude, which reflects the importance of taking the new effects into account.

    hep-phastro-ph.COgr-qcJHEP(2025)·19 citations
11. 11*

    AAK24: Global QCD analysis on polarized parton distribution in the presence of $A_2$ asymmetry measurements

    Fatemeh Arbabifar🇮🇷 · Shahin Atashbar Tehrani🇮🇷 · Hamzeh Khanpour🇮🇷

    This article introduces {\tt AAK24}, a Next-to-Leading Order (NLO) QCD analysis of polarized data from both polarized Deep Inelastic Scattering (DIS) and Semi-Inclusive Deep Inelastic Scattering (SIDIS) experiments on the nucleon. The {\tt AAK24} QCD analysis incorporates SU(2) and SU(3) symmetry breaking, specifically $\delta \bar{u}\ne \delta \bar{d}\ne \delta \bar{s}$, while assuming $\delta \bar{s}$ and $\delta s$ are equal. Emphasizing the significance of the semi-inclusive data, the study explores the determination of polarized sea quark distributions. Recent experimental data from {\tt JLAB17}, {\tt COMPASS16}, and {\tt COMPASS17}, including the $A_2$ asymmetry measurements along with SIDIS observables, are thoroughly examined for their impact on the central values of polarized PDFs, their uncertainties, and overall fit quality. Additionally, we include the nonperturbative target mass corrections (TMC) as well as higher-twist terms (HT) which are particularly important. In this work, the uncertainties are quantified using the standard Hessian method. The main results and findings of the {\tt AAK24} QCD analysis show overall good agreement with the analyzed experimental data, aligning well with other polarized PDF determinations, particularly {\tt DSSV14}, {\tt LSS10}, {\tt JAM17}, and {\tt AKS14}, all considering SU(2) and SU(3) symmetry breaking.

    hep-phEur.Phys.J.Plus(2024)·1 citation
12. 12*

    Cold Quark Matter: Renormalization Group Improvement at next-to-next-to leading order

    Loïc Fernandez🇫🇮 · Jean-Loïc Kneur🇫🇷

    We extend previous next-to-next-to leading order (NNLO) calculations of the QCD pressure at zero temperature and non-zero baryonic densities using the renormalization group optimized perturbation theory (RGOPT), which entails an all-order RG-invariant resummation. First, we consider the approximation of three massless quark flavors, and then adding the running strange quark mass dependence. The resulting pressure displays a sizeably reduced sensitivity to variations of the arbitrary renormalization scale as compared to the state-of-the-art NNLO results. This confirms previous NLO investigations that the RGOPT resummation scheme provides improved convergence properties and reduced renormalization scale uncertainties, thus being a promising prescription to improve perturbative QCD at high and mid range baryonic densities.

    hep-phPRD(2025)·11 citations
13. 13*

    On Nucleon "Radii"

    Vladimir A. Petrov🇷🇺

    We show that various nucleon "radii" that appear in the literature, e.g."charge", "gravitational", "mass" or "mechanical, do not have a direct geometric meaning and do not give an idea of the physical size of the nucleon. In the framework of the Gribov parton scheme we also show that at high enough energy a gluon cloud appears beyond the valence core of the nucleon and begins to determine the region of interaction of elastic nucleon-nucleon scattering and the growth of its cross-section.

    hep-ph3 citations
14. 14*

    Chiral oscillations in quantum field theory

    Victor Bittencourt🇫🇷 · Massimo Blasone🇮🇹 · Gennaro Zanfardino🇮🇹

    Dirac particles have two intrinsic degrees-of-freedom, helicity and chirality. While helicity is conserved in time, chirality is not constant under time evolution for massive particles, yielding the phenomenon of chiral oscillations. So far, chiral oscillations have been mainly described in the framework of single particle relativistic quantum mechanics. In this paper, we present a quantum field theory approach to chiral oscillations in analogy with the one used to describe flavor mixing and oscillations. By taking the expectation value of chiral charges, we obtain the same chiral oscillation formula derived via standard relativistic quantum mechanics. We find that chiral charges are diagonalized by a Bogoliubov transformation: this implies that the vacuum for particles with definite chirality is orthogonal to the one for those with definite energy. In the case of neutrinos, our results can be further extended to include also flavor oscillations.

    hep-phPLB(2025)·11 citations
15. 15*

    Heavy quark contributions in Bjorken sum rule with analytic coupling

    I.R. Gabdrakhmanov🇷🇺 · N.A Gramotkov🇷🇺 · A.V. Kotikov🇷🇺 · O.V. Teryaev🇷🇺 · D.A. Volkova🇷🇺 · I.A. Zemlyakov🇨🇱

    We consider heavy quark contributions to the polarized Bjorken sum rule. We found good agreement between the experimental data and the predictions of analytic QCD. To satisfy the limit of photoproduction, we use new representation of the perturbative part of the polarized Bjorken sum rule, proposed recently.

    hep-phJETP Lett.(2024)·8 citations
16. 16*

    Multi-Component Dark Matter from Minimal Flavor Violation

    Federico Mescia🇮🇹 · Shohei Okawa🇪🇸 · Keyun Wu🇪🇸

    Minimal Flavor Violation (MFV) offers an appealing framework for exploring physics beyond the Standard Model. Interestingly, within the MFV framework, a new colorless field that transforms non-trivially under a global $\mathrm{SU}(3{)}^3$ quark flavor group can naturally be stable. Such a new field is thus a promising dark matter candidate, provided it is electrically neutral. We extend the MFV framework for dark matter and demonstrate that dark matter can naturally be multi-component across a broad parameter space. For illustration, we consider a gauge singlet, flavor triplet scalar field and identify parameter spaces for multi-component dark matter, where only the lightest flavor component is absolutely stable and heavy flavor components are decaying with lifetimes sufficiently longer than the age of the universe. Phenomenological, cosmological and astrophysical aspects of multi-component flavored dark matter are briefly discussed.

    hep-phastro-ph.COhep-exJHEP(2024)·4 citations
17. 17*

    Minimal targets for dilaton direct detection

    David Cyncynates🇺🇸 · Olivier Simon🇺🇸

    Fifth force and equivalence principle tests search for new interactions by precisely measuring forces between macroscopic collections of atoms and molecules and their properties under free fall. In contrast, the early Universe plasma probes these interactions at a more fundamental level. In this paper, we consider the case of a scalar mediating a fifth force, and show that the effects of dimensional transmutation, spontaneous symmetry breaking, and the running of the gauge couplings cause the scalar's low-energy interactions to mix, leading to nearly universal dynamics at early times. We use known expressions for the pressure of the Standard Model during its various epochs to compute the scalar effective potential, and find that the cosmological dynamics of this scalar are very sensitive to the reheat temperature of the Universe. Given the unknown reheat temperature, we show that scalar couplings to matter larger than $\sim 10^{-6}(m_{\varphi }/\mathrm{eV}{)}^{-1/4}$ relative to gravity produce the correct dark matter abundance, motivating new physics searches in this part of parameter space.

    hep-phastro-ph.COhep-exhep-thPRD(2025)·24 citations
18. 18*

    Cosmological Stasis from a Single Annihilating Particle Species: Extending Stasis Into the Thermal Domain

    Jonah Barber🇺🇸 · Keith R. Dienes🇺🇸 · Brooks Thomas🇺🇸

    It has recently been shown that extended cosmological epochs can exist during which the abundances associated with different energy components remain constant despite cosmological expansion. Indeed, this "stasis" behavior has been found to arise generically in many BSM theories containing large towers of states, and even serves as a cosmological attractor. However, all previous studies of stasis took place within non-thermal environments, or more specifically within environments in which thermal effects played no essential role in realizing or sustaining the stasis. In this paper, we demonstrate that stasis can emerge and serve as an attractor even within thermal environments, with thermal effects playing a critical role in the stasis dynamics. Moreover, within such environments, we find that no towers of states are needed -- a single state experiencing two-body annihilations will suffice. This work thus extends the stasis phenomenon into the thermal domain and demonstrates that thermal effects can also generally give rise to an extended stasis epoch, even when only a single matter species is involved.

    ↳ astro-ph.COhep-phhep-thPRD(2024)·12 citations
19. 19*

    Premerger phenomena in neutron-star binary coalescences

    Arthur G. Suvorov🇪🇸 · Hao-Jui Kuan🇩🇪 · Kostas D. Kokkotas🇩🇪

    A variety of high-energy events can take place in the seconds leading up to a binary neutron-star merger. Mechanisms involving tidal resonances, electrodynamic interactions, or shocks in mass-loaded wakes have been proposed as instigators of these precursors. With a view of gravitational-wave and multimessenger astrophysics more broadly, premerger observations and theory are reviewed emphasising how gamma-ray precursors and dynamical tides can constrain the neutron-star equation of state, thermodynamic microphysics, and evolutionary pathways. Connections to post-merger phenomena, notably gamma-ray bursts, are discussed together with how magnetic fields, spin and misalignment, crustal elasticity, and stratification gradients impact observables.

    ↳ astro-ph.HEgr-qchep-exhep-ph+1Universe(2024)·20 citations
20. 20*

    Strange stars admixed with dark matter: equiparticle model in a two fluid approach

    Isabella Marzola🇧🇷 · Everson H. Rodrigues🇧🇷 · Anderson F. Coelho🇧🇷 · Odilon Lourenço🇧🇷

    In this work, we explore the possible scenario of strange stars admixed with fermionic or bosonic dark matter. For the description of the ``visible'' sector, we use a specific phenomenological quark model that takes into account in-medium effects for the quark masses through a suitable baryonic density dependence, in which the free parameters are chosen from the analysis of the stellar matter stability window (parametrizations presenting lower energy per baryon than iron nuclei). In the case of the dark sector, we investigate the predictions of fermionic and bosonic models. In the former, we consider a spin $1/2$ dark particle, and the latter is described by a dark scalar meson. Both models present a repulsive vector interaction, particularly important for the bosonic model since it helps avoid the collapse of the star due to the lack of degeneracy pressure. Our results point out possible stable strange stars configurations in agreement with data from the NASA NICER measurements of the pulsars PSR J0030+0451 and PSR J0740+6620, including the latest observational data, as well as the observed HESS J1731-347 mass-radius relationship. As another feature, we find stars with dark matter halo configurations for lower values of the dark particle mass.

    ↳ astro-ph.HEhep-phPRD(2025)·7 citations
21. 21*

    Distinguishing the sources of dielectron anisotropic flow at low beam energies

    Renan Hirayama🇩🇪 · Hannah Elfner🇩🇪

    We present calculations of dielectron anisotropic flow in heavy-ion collisions at HADES beam energies from a hadronic transport approach. The ongoing experimental analysis employs the traditional reaction plane method to evaluate the flow coefficients $v_n$ and claims to see isotropic radiation from the thermal quark-gluon plasma. We show in this work, that in the region above the pion mass, the dilepton flow measurement might suffer from cancellation effects that mask the complicated underlying dynamics. Contributions from different baryonic and mesonic resonances show collective behaviour with different signs and lead to an overall vanishing elliptic flow. To differentiate the different contributions, we propose to employ the scalar product method, which exploits the previously measured hadronic flow to create different reference planes. As a proof of concept, we calculate the $v_2$ of dielectrons for Ag+Ag collisions at $\sqrt{s_{NN}}=2.55$ $\mathrm{GeV}$ with both methods and investigate the contribution of each source, concluding that the scalar product method provides the proton and pion tagged flow coefficients as two distinct measurements, disentangling the various dilepton sources.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2024)·7 citations
22. 22*

    Flavor Dependence of Charged Pion Fragmentation Functions

    H. Bhatt🇺🇸 · P. Bosted🇺🇸 · S. Jia🇺🇸 · W. Armstrong🇺🇸 · D. Dutta🇺🇸 · R. Ent🇺🇸 · D. Gaskell🇺🇸 · E. Kinney🇺🇸 · H. Mkrtchyan · S. Ali🇺🇸 · R. Ambrose🇨🇦 · D. Androic🇭🇷 and 58 other authors

    We have measured the flavor dependence of multiplicities for pi^+ and pi^- production in semi-inclusive deep-inelastic scattering (SIDIS) on proton and deuteron targets to explore a possible charge symmetry violation in fragmentation functions. The experiment used an electron beam with energies of 10.2 and 10.6 GeV at Jefferson Lab and the Hall-C spectrometers. The electron kinematics spanned the range 0.3<x<0.6, 2<Q^2<5.5 GeV^2, and 4<W^2<11 GeV^2. The pion fractional momentum range was 0.3< z <0.7, and the transverse momentum range was 0<p_T<0.25 GeV/c. Assuming factorization at low p_T and allowing for isospin breaking, we find that the results can be described by two "favored" and two "un-favored" effective low $p_T$ fragmentation functions that are flavor-dependent. However, they converge to a common flavor-independent value at the lowest x or highest W of this experiment.

    ↳ nucl-exhep-phnucl-thPLB(2025)·7 citations
23. 23*

    Bounds on the minimum sound speed above neutron star densities

    Dake Zhou🇺🇸

    We show that the existence of massive neutron stars and asymptotic freedom of QCD place robust upper bounds on the lowest sound speed of the ultra-dense matter unattainable in neutron stars. Centered on worst-case scenarios, our limits are the most conservative among physical equations of state in the density range $\sim 2-40n_0$. Discovery of $\gtrsim 2.6M_{\odot }$ neutron stars, in combination with current multimessenger astrophysical constraints on the equation of state, would strongly support first-order phase transitions at high baryon densities.

    ↳ nucl-thastro-ph.HEgr-qchep-ph+11 citation

* 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.