Nuclear Theory·nucl-th

Friday·April 4, 2025

15 papers—10 primary·5 cross-listed

11
[Submitted on 2 Apr 2025] (cross-list from hep-ph)
Indications for freeze-out of charge fluctuations in the quark-gluon plasma at the LHC
Jonathan Parra🇺🇸 · Roman Poberezhniuk🇺🇸 · Volker Koch🇺🇸 · Claudia Ratti🇺🇸 · Volodymyr Vovchenko🇺🇸
The D-measure of net-charge fluctuations quantifies the variance of net charge in strongly interacting matter. It was introduced over 20 years ago as a potential signal of quark-gluon plasma (QGP) in heavy-ion collisions, where it is expected to be suppressed due to the fractional electric charges of quarks. Measurements have been performed at RHIC and LHC, but the conclusion has been elusive in the absence of quantitative calculations for both scenarios. We address this issue by employing a recently developed formalism of density correlations and incorporate resonance decays, local charge conservation, and experimental kinematic cuts. We find that the hadron gas scenario is in fair agreement with the ALICE data for $s_{NN} = 2.76$ TeV Pb-Pb collisions only when a very short rapidity range of local charge conservation is enforced, while the QGP scenario is in excellent agreement with experimental data and largely insensitive to the range of local charge conservation. A Bayesian analysis of the data utilizing different priors yields moderate evidence for the freeze-out of charge fluctuations in the QGP phase relative to hadron gas. The upcoming high-fidelity measurements from LHC Run 2 will serve as a precision test of the two scenarios.
Comments:
10 pages, 3 figures + supplemental material, version accepted for publication in Physical Review Letters
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2504.02085 [pdf]
PRL(2025)·8 citations
12
[Submitted on 3 Apr 2025] (cross-list from hep-ph)
Nonperturbative heavy quark diffusion coefficients in a weakly magnetized thermal QCD medium
Debarshi Dey🇮🇳 · Aritra Bandyopadhyay🇷🇴 · Santosh K. Das🇮🇳 · Sadhana Dash🇮🇳 · Vinod Chandra🇮🇳 · Basanta K. Nandi🇮🇳
In this work, the perturbative and non-perturbative contributions to the heavy quark (HQ) momentum ( $κ$ ) as well as spatial ( $D_{s}$ ) diffusion coefficients are computed in a weak background magnetic field. The formalism adopted here involves calculation of the in-medium potential of the HQ in a weak magnetic field, which then serves as a proxy for the resummed gluon propagator in the calculation of HQ self-energy ( $Σ$ ). The self-energy determines the scattering rate of HQs with light thermal partons, which is subsequently used to evaluate $κ$ and $D_{s}$ . It is observed that non-perturbative effects play a dominant role at low temperature. The spatial diffusion coefficient $2 π T D_{s}$ , exhibits good agreement with recent LQCD results. These findings can be applied to calculate the heavy quark directed flow at RHIC and LHC energies. An extension of this formalism to the case of finite HQ momentum has also been attempted.
Comments:
17 pages, 7 figures, version 2
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2504.02284 [pdf]
PRD(2025)·5 citations
13
[Submitted on 3 Apr 2025] (cross-list from hep-lat)
The temperature dependence of fractional topological charge objects
Jackson A. Mickley🇦🇺 · Waseem Kamleh🇦🇺 · Derek B. Leinweber🇦🇺
We present a novel method for defining the topological charge contained within distinct topological objects in the nontrivial ground-state fields of SU(N) lattice gauge theory. Such an analysis has been called for by the growing number of models for Yang-Mills topological structure which propose the existence of fractionally charged objects. This investigation is performed for SU(3) at a range of temperatures across the deconfinement phase transition, providing an assessment of how the topological structure evolves with temperature. This reveals a connection between the topological charge and holonomy of the system which must be satisfied by finite-temperature models of Yang-Mills vacuum structure. We find a promising consistency with the instanton-dyon model for SU(N) vacuum structure.
Comments:
12 pages, 4 figures. To appear as an invited contribution in the proceedings of the XVIth Quark Confinement and the Hadron Spectrum Conference (QCHSC24), 19-24 August 2024, Cairns Convention Centre, Cairns, Queensland, Australia
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2504.02297 [pdf]
PoS(2025)·2 citations
14
[Submitted on 3 Apr 2025] (cross-list from hep-ph)
ToMCCA-3: A realistic 3-body coalescence model
Maximilian Mahlein🇩🇪 · Bhawani Singh🇩🇪 · Michele Viviani🇮🇹 · Francesca Bellini🇮🇹 · Laura Fabbietti🇩🇪 · Alejandro Kievsky🇮🇹 · Laura Elisa Marcucci🇮🇹
The formation of light nuclei in high-energy collisions provides valuable insights into the underlying dynamics of the strong interaction and the structure of the particle-emitting source. Understanding this process is crucial not only for nuclear physics but also for astrophysical studies, where the production of rare antinuclei could serve as a probe for new physics. This work presents a three-body coalescence model based on the Wigner function formalism, offering a refined description of light-nucleus production. By incorporating realistic two- and three-body nuclear interaction potentials constrained by modern scattering and femtoscopic correlation data, our approach improves on traditional coalescence models. The framework is validated using event generators applied to proton-proton collisions at $s = 13$ TeV to predict the momentum spectra of light (anti) nuclear nuclei with mass number $A = 3$ , which are then compared with the experimental data from ALICE. Our results demonstrate the sensitivity of light nucleus yields to the choice of nuclear wave functions, emphasizing the importance of an accurate description of the coalescence process. This model lays the foundation for the extension of coalescence studies of $A = 3$ light nuclei to a wider range of collision systems and energies.
Comments:
23 pages, 4 Figures, 5 Figures in Appendix
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2504.02491 [pdf]
6 citations
15
[Submitted on 3 Apr 2025] (cross-list from hep-ph)
Backward DVCS in a Sullivan process
Abigail R. Castro🇫🇷 · Cédric Mezrag🇫🇷 · Jose M. Morgado Chávez🇫🇷 · Bernard Pire🇫🇷
Mesons' internal structure and dynamics may be accessed through hard exclusive electroproduction processes such as deeply virtual Compton scattering in both near forward and near backward kinematics. With the help of the Sullivan process which allows us to use a nucleon target as a quasi-real $π$ meson emitter, we study backward scattering in the framework of collinear QCD factorization where pion-to-photon transition distribution amplitudes describe the photon content of the $π$ meson. We present a model of these TDAs based on the overlap of lightfront wave functions primarily developed for generalized parton distributions, using a previously developed pion lightfront wave function and deriving a new model for the lightfront wave functions of the photon. This leads us to an estimate of the cross-sections for JLab energies. We conclude that deeply virtual $e p \to e γ M n$ processes, in backward kinematics, may be experimentally discovered in the near future.
Comments:
20 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2504.02657 [pdf]
PRD(2025)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Indications for freeze-out of charge fluctuations in the quark-gluon plasma at the LHC

Nonperturbative heavy quark diffusion coefficients in a weakly magnetized thermal QCD medium

The temperature dependence of fractional topological charge objects

ToMCCA-3: A realistic 3-body coalescence model

Backward DVCS in a Sullivan process

Affiliations