Nuclear Theory·nucl-th

Wednesday·April 8, 2026

14 papers—7 primary·7 cross-listed

08
[Submitted on 7 Apr 2026] (cross-list from astro-ph.HE)
Multiquark clustering in neutron-star matter from color-spin molecular dynamics
Nobutoshi Yasutake🇯🇵 · Yuta Mukobara🇮🇹 · Aaron Park🇰🇷 · Su Houng Lee🇰🇷 · Toshiki Maruyama🇯🇵
We study the equation of state of neutron-star matter with color-spin molecular dynamics. The calculation includes the internal color and spin degrees of freedom and their time evolution. The matter composition, including strangeness under $β$ equilibrium, is determined by energy minimization. We find two main trends. First, within the present color-spin molecular dynamics framework and under the adopted clustering criterion along the stable neutron-star branch, isolated quarklike configurations do not appear; instead, color-magnetic interactions favor the self-consistent formation of multiquark clusters. Within the same criterion, the cluster-size distribution is concentrated at quark numbers that are multiples of three, corresponding to integer baryon numbers. Second, relative to the conventional no- $K^{*}$ baseline, the interaction between strange and light quarks has a strong impact on neutron-star radii. This suggests that future radius measurements, together with phenomenological information on the strangeness-onset density, may help constrain flavor-sector interactions involving strangeness.
Comments:
14 pages, 9 figures; accepted for publication in Phys. Rev. D
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2604.05472 [pdf]
PRD(2026)·0 citations
09
[Submitted on 7 Apr 2026] (cross-list from hep-ph)
Non-universality of color transparency onset in pion and kaon electroproduction
Byung-Geel Yu · Tae Keun Choi · Kook-Jin Kong
A combined analysis of the Jefferson Lab data on nuclear transparency in $A (e, e^{'} π^{+})$ and $A (e, e^{'} K^{+})$ shows that the onset of color transparency (CT) is not universal across meson flavors. The pion transparency is well reproduced by the standard quantum diffusion model (QDM) with $Δ M_{π}^{2} ≃ 0.7$ GeV $^{2}$ , whereas the kaon data favor the quadratic expansion of the naive parton model (NPM) with the natural hadronic scale $R_{K} \sim σ_{K N} / π$ . This dichotomy cannot be repaired by physically motivated parameter choices: the pion slope excludes the quadratic expansion with any physical radius, and the kaon slope requires a QDM excitation scale far below the range conventionally used in pion transparency analyses. A microscopic interpretation, in which the diffusive evolution of the pion appears as an exceptional consequence of its Goldstone-boson nature while the kaon follows the generic ballistic expansion, is discussed.
Comments:
5 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.05612 [pdf]
0 citations
10
[Submitted on 7 Apr 2026] (cross-list from nucl-ex)
Probing the chiral magnetic effect via transverse spherocity event classification in relativistic heavy-ion collisions
Somdeep Dey🇮🇳 · Abhisek Saha🇨🇳
We present the first study of the Chiral Magnetic Effect (CME) using transverse spherocity as an event-shape classifier in Pb+Pb collisions at $s_{N N} = 5.02$ TeV, simulated with the A Multi-Phase Transport (AMPT) model with a realistic CME implementation. Transverse spherocity separates events into jetty and isotropic topologies based on the geometric distribution of transverse momentum. Unlike traditional event shape engineering methods, which use the flow vector as an event classifier that is itself contaminated by the very backgrounds it is intended to suppress, spherocity provides a cleaner, geometry-driven classification that avoids this circular limitation. CME inclusion shifts the spherocity distribution toward more isotropic events, confirming its sensitivity to CME-induced charge separation. The charge-dependent azimuthal correlator $Δ γ$ and correlated background coupled with elliptic flow are consistently higher in jetty events. The scaled ratio $Δ γ / v_{2}$ shows enhanced values for isotropic events, confirming effective background suppression after elliptic flow scaling. Our results demonstrate that isotropic event selection via transverse spherocity provides a cleaner and more reliable environment for CME searches by simultaneously suppressing flow-driven and resonance-decay backgrounds, making it a powerful complementary method to existing flow-vector-based methods.
Comments:
14 pages, 7 figures
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.05654 [pdf]
0 citations
11
[Submitted on 7 Apr 2026] (cross-list from nucl-ex)
Observation of nuclear suppression in coherent $Υ$ (1S) photoproduction off heavy nuclei at the LHC
CMS Collaboration
The first measurement of coherent $Υ$ (1S) meson photoproduction off heavy nuclei is performed using ultraperipheral lead-lead collisions collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The nuclear gluonic structure is probed at a nucleon momentum fraction of order $x$ $\sim$ 10 $^{- 3}$ , determined by the kinematics of the process. Owing to the large $Υ$ (1S) mass, the measurement reaches the highest scale accessible so far through coherent vector-meson photoproduction, $μ^{2}$ = 22.4 GeV $^{2}$ , where nonlinear quantum chromodynamics effects are expected to be minimal. In the $Υ$ (1S) rapidity range $∣ y ∣$ $<$ 1, the ratio of the measured photoproduction cross section to a baseline model prediction that neglects nuclear effects is $S_{Υ (1S)}$ = 0.25 $\pm$ 0.06 (stat) $\pm$ 0.02 (syst), thereby demonstrating nuclear suppression in this process. Expressed in terms of a nuclear gluon suppression factor, the result yields $R_{g}^{Pb}$ ( $x$ $\approx$ 10 $^{- 3}$ , $μ^{2}$ = 22.4 GeV $^{2}$ ) = 0.55 $\pm$ 0.12 (stat) $\pm$ 0.02 (syst). The measured $R_{g}^{Pb}$ is only slightly larger than the values previously reported for coherent $ϕ$ photoproduction, despite the probed $μ^{2}$ differing by approximately two orders of magnitude.
Comments:
Submitted to Physical Review Letters. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-24-013 (CMS Public Pages)
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2604.05814 [pdf]
4 citations
12
[Submitted on 7 Apr 2026] (cross-list from hep-ph)
Thermodynamic and Transport Properties of Quark-Gluon Plasma at Finite Chemical Potential with a DNN framework
Rishabh Kumar Tiwari🇮🇳 · Kangkan Goswami🇮🇳 · Suraj Prasad🇮🇳 · Captain R. Singh🇮🇳 · Raghunath Sahoo🇮🇳 · Mohammad Yousuf Jamal🇨🇳
The characteristics of a thermal system depend strongly on its response to thermal gradients and the underlying microscopic interactions among constituents. In the present study, we investigate the thermodynamic and transport properties of the quark-gluon plasma (QGP) at finite baryon chemical potential within a deep-learning-assisted quasi-particle model (DLQPM). The temperature ( $T$ ) and baryon chemical potential ( $μ_{B}$ )-dependent thermal masses of quasi-particles are estimated using neural networks trained to reproduce lattice QCD (lQCD) results for the equation of state, obtained via a Taylor-like expansion around vanishing baryon chemical potential. The trained model acts as an effective emulator, enabling us to estimate the thermodynamic and transport properties at finite $μ_{B}$ . We compute the speed of sound, specific heat, viscosity, and conductivity of the deconfined medium. Our findings are in good agreement with available lattice calculations and other phenomenological models. The present study demonstrates that a DNN-based approach provides an efficient framework for studying the properties of the QGP at finite baryon density.
Comments:
11 pages and 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2604.05858 [pdf]
2 citations
13
[Submitted on 7 Apr 2026] (cross-list from hep-th)
$N = 4$ supersymmetric Yang-Mills thermodynamics to order $λ^{5/2}$
Margaret E. Carrington🇨🇦 · Gabor Kunstatter🇨🇦 · Ubaid Tantary🇸🇦
We calculate the resummed perturbative free energy of $N = 4$ supersymmetric Yang-Mills in four spacetime dimensions (SYM $_{44}$ ) to order $λ^{5/2}$ in the 't Hooft coupling at finite temperature and zero chemical potential. All infrared divergences cancel when we include contributions from SYM $_{44}$ ring diagrams and the final result is both ultraviolet and infrared finite. Our result has special significance since order $λ^{5/2}$ is the highest order calculation that can be done with perturbation theory, because there are nonperturbative effects associated with the magnetic mass scale that come into play at order $λ^{3}$ . We compare results obtained with regularization by dimensional reduction (RDR), which preserves supersymmetry, and canonical dimensional regularization (DR). We also compare with a generalized Padé approximant constructed by matching the weak coupling result at order $λ^{2}$ and the large $N_{c}$ strong coupling result at order $λ^{- 3/2}$ . Finally we make a comparison between our result and the QCD free energy and show that SYM $_{44}$ has better convergence properties.
Comments:
40 pages, 7 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.05919 [pdf]
PRD(2026)·2 citations
14
[Submitted on 7 Apr 2026] (cross-list from physics.chem-ph)
Reference Energies for Non-Relativistic Core Ionization Potentials
Antoine Marie · Loris Burth · Pierre-François Loos
Deep-lying core electrons carry highly localized, site-specific information that forms the basis of X-ray photoelectron spectroscopy. Accurately predicting their associated core ionization potentials (IPs) is a demanding theoretical task, requiring a balanced treatment of strong orbital relaxation, electron correlation, and relativistic effects. Over the years, a variety of approaches have been developed, ranging from state-specific wave function methods to linear-response formalisms and Green's function techniques. However, their assessment has often relied on comparisons with experiment, where multiple sources of error (basis set incompleteness, relativistic corrections, and vibrational effects) are entangled, making it difficult to isolate the performance of correlation treatments. In the present work, we establish a consistent, theory-based benchmark for core IPs by computing 84 non-relativistic values (73 second-row and 11 third-row IPs) at the full configuration interaction level within the core-valence separation approximation, using large correlation-consistent basis sets augmented with tight-core and diffuse functions (aug-cc-pCVXZ). These results define theoretical best estimates within a fixed finite basis set, providing a chemically accurate reference for method development and validation. Importantly, our dataset allows for systematic, theory-versus-theory comparisons that disentangle correlation and relaxation effects from other physical contributions. On this basis, we assess the performance of widely used approximate methods, including equation-of-motion coupled-cluster approaches up to the inclusion of quadruple excitations, the one-shot $G_{0} W_{0}$ scheme, as well as state-specific methods.
Comments:
13 pages, 3 figure (Supporting Information available)
Subjects:
physics.chem-ph (physics.chem-ph); cond-mat.mtrl-sci (cond-mat.mtrl-sci); Nuclear Theory (nucl-th)
arXiv:
2604.05920 [pdf]
J.Chem.Theor.Comput.(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Multiquark clustering in neutron-star matter from color-spin molecular dynamics

Non-universality of color transparency onset in pion and kaon electroproduction

Probing the chiral magnetic effect via transverse spherocity event classification in relativistic heavy-ion collisions

Observation of nuclear suppression in coherent Υ(1S) photoproduction off heavy nuclei at the LHC

Thermodynamic and Transport Properties of Quark-Gluon Plasma at Finite Chemical Potential with a DNN framework

N=4 supersymmetric Yang-Mills thermodynamics to order λ5/2

Reference Energies for Non-Relativistic Core Ionization Potentials

Affiliations

Observation of nuclear suppression in coherent $Υ$ (1S) photoproduction off heavy nuclei at the LHC

$N = 4$ supersymmetric Yang-Mills thermodynamics to order $λ^{5/2}$