Nuclear Theory·nucl-th

Friday·August 21, 2026

13 papers—3 primary·10 cross-listed

04
Heavy quark transport in quark-gluon plasma beyond the non-relativistic limit
Krishna Rajagopal🇺🇸 · Bruno Scheihing-Hitschfeld🇺🇸 · Urs Achim Wiedemann🇨🇭
The dynamics of heavy quarks in quark-gluon plasma (QGP) formed in heavy ion collisions provide a unique window to characterize its properties. Existing approaches to describe heavy quarks in medium rely either on quasiparticle-based models of QGP, or on assuming that the momentum transfer from the medium follows Gaussian statistics. However, neither of these assumptions can be taken for granted in QCD. In fact, in the prototypical theory that is strongly coupled $N = 4$ SYM, it has been long known there are no momentum-carrying quasiparticles, and furthermore, we have recently shown that the momentum transfer from the medium is far from being Gaussian [arXiv:2501.06289]. Since then, we showed that the asymmetry of said momentum transfer between energy loss and energy gain -- which affects all moments of the distribution, not only its Gaussian characteristics -- is, in fact, universal [arXiv:2504.21139]. Therefore, in order to connect the initial heavy quark production cross section with the final hadron spectrum in a way that is consistent with QFT principles, new methods are needed. In this talk, we present a new transport description of heavy quarks that encodes all of the non-Gaussian features of the momentum transfer from the medium, all of which can be defined and in principle calculated in QCD, without relying on any assumptions regarding the strength of the coupling. As a demonstrative example, we discuss heavy quark equilibration in $N = 4$ SYM. This paves the way towards extracting novel information about fundamental properties of QGP.
↳ hep-phnucl-th0 citations
05
The QCD crossover temperature and curvature coefficient from unbiased exponential resummation at physical quark masses in (2+1)-flavor lattice QCD
Sabarnya Mitra🇩🇪
We present the first application of the unbiased exponential resummation method to the determination of the QCD pseudocritical temperature $T_{pc}$ at vanishing baryon chemical potential $μ_{B}$ . By reconstructing the finite-density baryon number susceptibility $χ_{2}^{B}$ , we define two thermal-derivative observables whose peak positions yield $T_{pc}^{T} = 160.2 (4) (3)$ MeV and $T_{pc}^{C} = 158.1 (5) (3)$ MeV. We also show that the pseudocritical temperature, $T_{pc}^{χ}$ obtained from the peak of the fourth-order baryon number susceptibility $χ_{4}^{B}$ is consistent with these determinations and with previous lattice-QCD results based on Taylor expansions \cite{Bollweg:2022Pade}. Further, we demonstrate that scaling relations \cite{Bollweg:2022fqq} between $χ_{4}^{B}$ and the thermal derivatives of $χ_{2}^{B}$ yield mutually consistent estimates of the leading second order curvature coefficient $κ_{2}^{B}$ at the corresponding pseudocritical temperatures. A direct analysis of the $μ_{B}$ dependence of the pseudocritical temperatures provides an independent but substantially less constrained determination of the curvature, which remains statistically consistent with the scaling-based estimates. These results demonstrate the consistency of unbiased exponential resummation with the expected scaling behavior and establish it as a complementary approach for probing the QCD crossover at small finite baryon density.
↳ hep-lathep-phhep-thnucl-ex+10 citations
06
Breakdown of Hydrodynamic Universality in Neutron Star Oscillations
Gabriel S. Denicol🇧🇷 · Amanda Guerrieri🇧🇷 · João V. M. Muniz🇧🇷 · Gabriel S. Rocha🇧🇷 · Raissa F. P. Mendes🇧🇷
Hydrodynamic universality refers to the property that different formulations of relativistic dissipative hydrodynamics yield identical predictions in the asymptotic long-wavelength regime. We show that neutron-star oscillations need not reach this regime. Because the finite stellar radius limits the accessible wavelengths and causality imposes a lower bound on microscopic relaxation times, the separation between microscopic and macroscopic scales can become insufficient for hydrodynamic universality to emerge. Comparing linear oscillations in relativistic Navier--Stokes and Israel--Stewart theories, we find that realistic bulk viscosities can produce sizeable modifications of the oscillation spectrum, even at the longest wavelengths. These results identify neutron-star oscillations as a direct probe of microscopic nonequilibrium dynamics beyond the leading hydrodynamic description.
↳ gr-qcnucl-th0 citations
07
Discovery of Three Glitches in the previously quiet pulsar PSR J1637 $-$ 4642
Zhaoyi Wang · Chuwen Zheng · Yuhong Zhuang · Hanyu Zhang · Peng Liu · Zhonghao Tu · Ang Li
We present the discovery and analysis of three rotational glitches in the young pulsar PSR J1637 $-$ 4642. The timing observations span from 19 February 2009 to 6 October 2024 (MJD 54881 $-$ 60589) from the Murriyang radio telescope of the Parkes Observatory. The first and strongest glitch occurred around MJD 58352 with a fractional frequency change of $Δ ν / ν \sim 2.7 \times 1 0^{- 6}$ , while two additional smaller glitches were detected at MJD 59443 and MJD 60445 with fractional changes of $2.2 \times 1 0^{- 9}$ and $2.8 \times 1 0^{- 8}$ , respectively. Prior to this, the pulsar had shown no glitch activity since its discovery in the Parkes Multibeam survey. Only the first glitch exhibits detectable exponential recovery, with a decay timescale of $\sim$ 100 days and a small recovery fraction $\approx 0.015$ , accompanied by a permanent increase in the magnitude of the spin-down rate. Modeling the post-glitch evolution of $ν ˙$ within the vortex-creep framework using Bayesian inference gives a superfluid moment-of-inertia fraction $\approx 0.0187$ , consistent with the inner-crust superfluid. These results reinforce the standard superfluid glitch paradigm and demonstrate that even ``quiet'' pulsars can still host substantial glitch activity.
↳ astro-ph.HEastro-ph.SRnucl-th0 citations
08
Tracing Vacuum Hadronization with Conserved Currents
Weiyao Ke🇨🇳 · Hai Tao Li🇨🇳 · Wanchen Li🇨🇳 · Xiaohui Liu🇨🇳 · Ding Yu Shao🇨🇳
We show that color triality constrains the nonperturbative states that screen a Wilson-line endpoint, allowing the joint flows of net electric charge, baryon number, and strangeness to probe QCD vacuum hadronization. Whether evaluated from resolved hadrons in a jet initiated by a quark of flavor $f$ or from the corresponding charge correlators, these flows satisfy the Gell-Mann--Nishijima relation $⟨ Q_{flow} ⟩_{f} ≃ I_{3, f} + \frac{1}{2} (⟨ S_{flow} ⟩_{f} + ⟨ B_{flow} ⟩_{f})$ , where $I_{3, f}$ is the third component of the initiating-quark isospin. The net jet baryon number, $⟨ B_{flow} ⟩_{f} ≃ \frac{r _{q q}}{1 + r _{q q}}$ , directly probes the relative probability of a diquark--antidiquark vacuum excitation, with $r_{q q}$ the diquark-to-quark production ratio. Thus, for $r_{q q} ≪ 1$ , the baryon number carried by the jet is substantially suppressed relative to the initiating-quark value $B_{f} = 1/3$ . Likewise, the strange-to-light pair-production ratio, defined by $u u ˉ : d d ˉ : s s ˉ = 1 : 1 : r_{s}$ , is encoded in the measured jet strangeness $⟨ S_{flow} ⟩_{f} ≃ S_{f} + \frac{3 r _{s}}{2 + r _{s}} (\frac{1}{3} - ⟨ B_{flow} ⟩_{f})$ , predicting a nonzero mean net strangeness even in $u$ - and $d$ -initiated jets. The conserved-current moments appearing in these relations are independent of the renormalization scale. Their simultaneous measurement therefore provides a direct, flavor-resolved probe of vacuum pair production and quantum-number transport during hadronization.
↳ hep-phhep-exnucl-exnucl-th0 citations
09
Skewness dependence of the pion and kaon generalized parton distributions
Fernando Chandra🇮🇩 · Parada T. P. Hutauruk🇯🇵 · Terry Mart🇮🇩
We investigate the skewness dependence of the pion generalized parton distribution (GPD) at different momentum transfers $- t$ within the covariant Nambu-Jona-Lasinio (NJL) model, employing the Schwinger proper-time regularization scheme to regulate ultraviolet divergences and implement an effective description of quark confinement. We evolve the pion GPDs for various values of $- t$ and $ξ$ to the scales $μ^{2} = 4$ and $27 GeV^{2}$ . We find that the valence-quark distributions are suppressed with increasing $- t$ and $ξ$ , with the suppression becoming more pronounced at the lower scale, $μ^{2} = 4 GeV^{2}$ . In the forward limit, $ξ = 0$ and $- t = 0$ , the predicted pion valence-quark distribution at $μ^{2} = 27 GeV^{2}$ is in good agreement with the available experimental data and the global JAM analysis. The corresponding pion gluon distribution at $μ^{2} = 4 GeV^{2}$ , obtained through next-to-leading-order (NLO) DGLAP evolution, is also consistent with the JAM analysis. We further find that the pion and kaon valence-quark distributions exhibit a strong dependence on $- t$ but only a weak dependence on $ξ$ , whereas the corresponding gluon distributions show weak dependence on both $- t$ and $ξ$ . The generalized form factors of the pion and kaon at $μ^{2} = 4 GeV^{2}$ are in good agreement with the corresponding lattice-QCD results.
↳ hep-phnucl-th0 citations
10
Imaginary time evolution of a quantum system through analytic continuation from real-time quantum simulation
Peng Guo · Anto Shibu · Joshua Lin · Yong Zhao
Though quantum computing naturally offers an advantage for simulations of real-time quantum systems, implementing Imaginary-Time Evolution (ITE) is comparatively more difficult. Nevertheless, quantum implementations of ITE are useful both in cases where classical implementations have associated sign problems, and also as an exact method of preparing eigenstates on quantum computers. In this work we present an algorithm to obtain ITE of a generic quantum Hamiltonian by performing analytic continuation of measured real-time correlation functions. We present simulations and demonstrations on IBM quantum hardware of 1D Fokker-Planck equations for classical diffusion process and imaginary-time evolution of integrated correlation functions in 1D quantum mechanical scattering as examples to demonstrate the effectiveness of the method.
↳ quant-phcond-mat.otherhep-lathep-ph+10 citations
11
Lattice-data-driven specific heat and isentropic bulk modulus of SU(3) gluon matter at finite temperature
Wei Shen🇨🇳 · Zhen-Yan Lu🇨🇳 · Muhammad Waqas🇨🇳 · Xun Chen🇨🇳 · Zhi-Jun Ma🇨🇳 · Guang-Xiong Peng🇨🇳
We investigate the specific heat and isentropic bulk modulus of finite-temperature pure SU(3) gauge matter within a lattice-data-driven phenomenological framework. The equation of state is formulated in terms of a temperature-dependent effective gluon mass constrained { by lattice QCD pressure data as input, allowing the pressure}, trace anomaly, gluon number density, energy per thermally active gluonic mode, and derivative-sensitive response functions to be derived in a thermodynamically consistent manner. The resulting pressure and trace anomaly reproduce the characteristic lattice behavior across the deconfinement region, while the effective gluonic degrees of freedom increase rapidly above $T_{c}$ . The normalized specific heat $C_{V} / T^{3}$ develops a pronounced enhancement in the vicinity of $T_{c}$ , reflecting the rapid temperature variation of the energy density across the deconfinement region. The isentropic bulk modulus $K_{S} / T^{4}$ also rises sharply across the transition region, indicating a substantial stiffening of the equation of state. At high temperatures, both response functions gradually approach values close to their massless conformal Stefan--Boltzmann reference values, with $(C_{V} / T^{3})_{SB} = 32 π^{2} /15 ≃ 21.06$ and $(K_{S} / T^{4})_{SB} = 32 π^{2} /135 ≃ 2.34$ . These findings indicate that the specific heat and isentropic bulk modulus provide complementary constraints on the temperature evolution of nonconformal dynamics in pure SU(3) gauge matter.
↳ hep-phhep-thnucl-th0 citations
12
Negative diffusion in the Functional Renormalization Group flow for the Quark-Diquark Model
Johannes Poeplau · Ashutosh Dash · Dirk H. Rischke
We investigate the Quark-Diquark Model (QDM) with the Functional Renormalization Group (FRG) in the Local Potential Approximation. In a recent work [arXiv:2510.01066 [hep-ph]], problems were reported in applying this method at low temperatures and large quark chemical potentials, which were attributed to numerical artifacts. In this work, we trace the origin of these problems to the occurrence of a negative diffusion coefficient during the FRG flow of the derivative of the effective potential, leading to strong oscillations of the latter quantity. We show that negative diffusion is a model feature and not a numerical artifact. We propose a regularization scheme which introduces a hyperdiffusion term to remove these oscillations and demonstrate its effectiveness for studies of the phase diagram of the QDM. Regularizing the negative diffusion in the FRG flow is particularly important to reliably study phenomena such as color superconductivity and inhomogeneous phases, which might emerge in the high-density, low-temperature region of the QCD phase diagram.
↳ hep-phhep-thnucl-th0 citations
13
QED radiative effects in semi-inclusive deep-inelastic scattering: traditional and factorized approaches
Igor Akushevich🇺🇸 · Haiyan Gao🇺🇸 · Alexander Ilyichev🇧🇾 · Shuo Jia🇺🇸 · Vladimir Khachatryan🇺🇸 · Youjie Lin🇨🇳 · Tianbo Liu🇨🇳 · W. Melnitchouk🇺🇸
Semi-inclusive deep-inelastic scattering (SIDIS) of leptons is a vital tool for probing the three-dimensional momentum space partonic structure of the nucleon. Reliable extraction of the intrinsic collinear or transverse momentum dependent parton distributions from SIDIS data requires careful treatment of QED radiative effects beyond the Born level. In this work we perform a detailed comparative analysis of QED effects in SIDIS using the traditional Bardin-Shumeiko approach, augmented by the electron structure function method, and a more recent factorized approach that treats QED and QCD radiation on equal footing. We compare analytical and numerical results of these approaches for the unpolarized $π^{+}$ electroproduction cross sections off the proton and the Collins and Sivers transverse single-spin asymmetries, and identify the sources of discrepancies between the calculations, which for the cross sections can reach up to $\approx 2%$ , $\approx 7%$ , and $\approx 5%$ at Jefferson Lab, HERMES, and EIC kinematics, respectively. To provide a unified approach for reliably extracting partonic information from future SIDIS measurements, we propose a hybrid framework that employs the salient features of both frameworks in their respective regions of applicability.
↳ hep-phhep-exnucl-exnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE