Nuclear Theory·nucl-th

Friday·July 18, 2025

8 papers—2 primary·6 cross-listed

03
Systematics from NICER Pulse Profiles Drive Uncertainty in Multi-Messenger Inference of the Neutron Star Equation of State
Bhaskar Biswas🇩🇪 · Prasanta Char🇪🇸
We present new constraints on the neutron star equation of state (EOS) and mass distribution using a unified Bayesian inference framework that incorporates latest NICER measurements, including PSR J0614 $-$ 3329, alongside gravitational wave data, radio pulsar masses, and nuclear theory. By systematically comparing four inference scenarios--varying in the inclusion of PSR J0614 $-$ 3329 and in the pulse profile model used for PSR J0030+0451--we quantify the impact of observational and modeling choices on dense matter inference. We find that pulse profile systematics dominate EOS uncertainties: the choice of hot spot geometry for PSR J0030+0451 leads to significant shifts in the inferred stiffness of the EOS and maximum neutron star mass. In contrast, PSR J0614 $-$ 3329 mildly softens the EOS at low densities, reducing the radius at $1.4\,M_\odot$ by $\sim 100$~m. A Bayesian model comparison yields a Bayes factor of $lo g_{10} BF \approx 1.58$ in favor of the ST+PDT model over PDT-U, providing strong evidence that multi-messenger EOS inference can statistically discriminate between competing NICER pulse profile models. These results highlight the critical role of NICER systematics in dense matter inference and the power of joint analyses in breaking modeling degeneracies.
↳ astro-ph.HEgr-qcnucl-thPRD(2025)·4 citations
04
Parton distribution and fragmentation functions with massive gluons
Gustavo B. Bopsin🇧🇷 · Bruno El-Bennich🇧🇷 · Gastão Krein🇧🇷 · Fernando E. Serna🇨🇴 · Roberto C. da Silveira🇧🇷
The correct description of the hadron's structure requires understanding how quarks and gluons form the observable hadrons and how they are distributed within them. Two key nonperturbative quantities encapsulate this information: parton distribution functions (PDFs) and fragmentation functions (FFs). The former define a probabilistic light-front momentum distribution of partons within a hadron, whereas the latter describe the hadronization process of high-energy partons. Computing these functions analytically poses significant challenges, as it demands models that accurately incorporate the nonperturbative infrared dynamics of Quantum Chromodynamics (QCD). In this work, we compute the pion PDF and its elementary and full FFs using the Curci-Ferrari (CF) model. This model enables the exploration of nonperturbative QCD effects by introducing a gluon-mass scale within the Landau gauge QCD Lagrangian. The two-point quark and gluon correlation functions derived from the CF model agree well with lattice QCD results and reproduce the pion decay constant in the chiral limit, consistent with chiral perturbation theory. The resulting pion PDF and FFs computed with the CF quark propagator and pion Bethe-Salpeter amplitude are in good qualitative and quantitative agreement with those obtained using the Qin-Chang model, a benchmark approach to nonperturbative QCD. These findings support the broader applicability of the Curci-Ferrari model in hadron phenomenology.
↳ hep-phhep-exnucl-thPRD(2025)·5 citations
05
Parton Distribution Functions and their Generalizations
Cédric Lorcé (Ecole Polytechnique, CPHT)🇫🇷 · A. Metz (Temple U.)🇺🇸 · B. Pasquini (Pavia U. and INFN, Pavia)🇮🇹 · P. Schweitzer (Connecticut U.)🇺🇸
This article is an introduction to parton distribution functions and their generalizations which describe the quark and gluon structure of hadrons, and can be measured in various high-energy scattering processes. We provide the theoretical background, highlight both historical and recent developments, explain the connections between the different functions, and expose in which processes these functions can be accessed and what we can learn from them about hadron structure.
↳ hep-phhep-exhep-latnucl-ex+1Encyclopedia of Particle Physics, Volume …·35 citations
06
Effect of Dark matter and $σ$ -cut potential on radial and non-radial oscillation modes in neutron stars
Prashant Thakur🇮🇳 · Ishfaq Ahmad Rather🇩🇪 · Y. Lim🇰🇷
We study the mesonic nonlinear (NL) interaction equation of state (EoS) employing the relativistic mean-field model and investigate the effect of $σ$ -cut potential (NL- $σ$ cut) and dark matter (NL DM) on the non-radial and radial oscillation modes of neutron stars. For NL- $σ$ cut, we include the $σ$ -cut potential $U_{c u t} (σ)$ to study its effect. For the dark matter, we use the neutron decay anomaly model. For each model, we investigate two extreme EoSs, stiff and soft, that cover the entire allowed parameter range from the given model, consistent with the current astrophysical constraints. The EoS and the stellar properties, such as mass and radius, are calculated, and the effect of $σ$ -cut and DM is discussed. Both non-radial and radial oscillation modes are computed in the general relativistic framework. We study the non-radial $f$ and $p_{1}$ mode frequency, damping time, and some qusi-universal relations connecting the frequencies of the $f$ -mode to the average density and compactness. The analysis showed that the $f$ and $p_{1}$ mode frequencies at both 1.4~ $M_{⊙}$ and the maximum mass configuration are higher in the NL DM model compared to the NL and NL- $σ$ models. The consistent alignment between our prior parameterizations and current calculations strongly supports the existence of quasi-universal relations that hold true irrespective of the particular matter components involved. For the radial oscillations, we compute 10 lowest-order modes ( $f$ , $p$ ), study the radial perturbations as well as the large frequency separation with NL- $σ$ cut and NL DM EoS, showing that the microphysics involved in the NS EoS is imprinted on the frequency separation between different nodes.
↳ astro-ph.HEhep-phnucl-thPRD(2025)·5 citations
07
Thermal Radiation from an Analytic Hydrodynamic Model with Hadronic and QGP Sources in Heavy-Ion Collisions
Gábor László Kasza🇭🇺
In high-energy heavy-ion collisions, a nearly perfect fluid is formed, known as the strongly coupled quark-gluon plasma (QGP). After a short thermalization period, the evolution of this medium can be described by the equations of relativistic hydrodynamics. As the system expands and cools, the QGP undergoes a transition into hadronic matter, marking the onset of quark confinement. Direct photons offer insights into an essential stage of evolution, spanning from the onset of thermalization to the suppression of thermal photon production, which occurs within the hadronic phase. This paper builds upon and extends a previously published solution of relativistic hydrodynamics, incorporating an equation of state that falls within the same class as that predicted by lattice QCD. Based on this solution, a completely analytic model is constructed to describe thermal photon production, accounting for the quark-hadron transition. The model is tested against PHENIX measurements of non-prompt direct photon spectra in Au+Au collisions at $s_{N N} = 200$ GeV. Good agreement is observed between the model predictions and the experimental data, enabling the investigation of the centrality dependence of the initial temperature. These results provide a benchmark for future theoretical and experimental studies of thermal radiation in heavy-ion collisions.
↳ hep-phnucl-thPTEP(2026)·3 citations
08
High-precision baryon number cumulants from lattice QCD in a finite box: cumulant ratios, Lee-Yang zeros and critical endpoint predictions
Alexander Adam🇩🇪 · Szabolcs Borsányi🇩🇪 · Zoltan Fodor🇩🇪 · Jana N. Guenther🇩🇪 · Piyush Kumar🇩🇪 · Paolo Parotto🇮🇹 · Attila Pásztor🇭🇺 · Chik Him Wong🇩🇪
We have performed high-statistics lattice simulations using 4HEX improved staggered fermions on $1 6^{3} \times 8$ lattices. We calculated the Taylor expansion coefficients of the pressure with respect to the baryochemical potential to the tenth order at zero, and fourth order at purely imaginary chemical potentials. We used this data to construct rational function approximations of the free energy. We use a rational ansatz that explicitly satisfies the charge conjugation symmetry and the Roberge-Weiss periodicity, which are exact properties of the QCD free energy. We use this ansatz to estimate the position of Lee-Yang zeros in the complex chemical potential plane. The temperature dependence of the imaginary part of the Lee-Yang zeros is then fitted with ansätze motivated by the universal behavior of the free energy near a 3D Ising critical point. In principle, this allows one to estimate the temperature of the critical endpoint. We consider several sources of systematic errors. On this single lattice spacing we find that with $84%$ probability, the chiral critical endpoint is either below $103$ ~MeV temperature or it does not exist. We also identify some caveats of the method, which do not disappear even with the extremely high statistics of this present study. We discuss to what extent these can be eliminated by future high statistics lattice analyses.
↳ hep-latcond-mat.stat-mechhep-phnucl-thPRD(2026)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE

Systematics from NICER Pulse Profiles Drive Uncertainty in Multi-Messenger Inference of the Neutron Star Equation of State

Parton distribution and fragmentation functions with massive gluons

Parton Distribution Functions and their Generalizations

Effect of Dark matter and σ-cut potential on radial and non-radial oscillation modes in neutron stars

Thermal Radiation from an Analytic Hydrodynamic Model with Hadronic and QGP Sources in Heavy-Ion Collisions

High-precision baryon number cumulants from lattice QCD in a finite box: cumulant ratios, Lee-Yang zeros and critical endpoint predictions

Affiliations

Effect of Dark matter and $σ$ -cut potential on radial and non-radial oscillation modes in neutron stars