Nuclear Theory·nucl-th

Friday·August 29, 2025

14 papers—7 primary·7 cross-listed

01
Chiral restoration temperature at finite spin density in QCD
Pracheta Singha🇷🇴 · Victor E. Ambrus🇷🇴 · Sergiu Busuioc🇷🇴 · Aritra Bandyopadhyay🇷🇴 · Maxim N. Chernodub🇷🇴
We investigate the impact of a uniform spin density on the critical temperature of the chiral phase transition in finite-temperature QCD in the scope of the linear sigma model. We demonstrate that at a finite spin potential $μ_{Σ}$ , corresponding to a finite spin density, the predictive power of the model is challenged by an ambiguity associated with a contribution of the vacuum renormalization term to the free energy. Eliminating the regularization freedom through comparison with recent low- $μ_{Σ}$ lattice data, we extend the phase diagram of QCD at finite spin density to regions inaccessible to lattice simulations. We show that, as the spin potential increases, the temperature of the chiral crossover transition diminishes and the chiral crossover turns into a first-order transition at a second-order critical end-point $(T, μ_{Σ})_{CEP} ≃ (0.142, 0.098)$ GeV. With increasing spin potential, the critical temperature touches the zero-temperature axis at $μ_{Σ} = 0.310$ GeV, implying that the chiral symmetry is restored at higher potentials at any temperature.
nucl-thhep-thPRD(2026)·3 citations
02
Configuration mixing effects on neutrinoless $β β$ -decay nuclear matrix elements
Kosuke Nomura🇯🇵
Mixing and coexistence of intrinsic nuclear shapes play an important role to determine the low-energy structure of heavy nuclei, and are expected to affect nuclear matrix elements (NMEs) of neutrinoless double beta ( $0 ν β β$ ) decay. This problem is addressed in the interacting boson model with configuration mixing that is formulated by using the nuclear energy density functional theory. It is shown that significant amounts of mixing of normal and deformed intruder configurations are present in the ground and excited $0^{+}$ states in the even-even nuclei that are parent or daughter nuclei of the $0 ν β β$ decay. An illustrative application to the $0 ν β β$ decays of $^{76}$ Ge, $^{96}$ Zr, $^{100}$ Mo, $^{116}$ Cd, and $^{150}$ Nd shows that the inclusion of the configuration mixing reduces the NMEs for most of the $0_{1}^{+}$ $\to$ $0_{1}^{+}$ $0 ν β β$ decays.
nucl-thnucl-exPLB(2025)·3 citations
03
Perturbative high-energy evolution in the IP-Glasma initial state
Heikki Mäntysaari🇫🇮 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸
We include the perturbative JIMWLK energy evolution into the IP-Glasma initial state description used to simulate the early-time dynamics in heavy ion collisions. By numerically solving the JIMWLK equation on an event-by-event basis, we obtain the energy (Bjorken- $x$ ) dependent structure of the colliding nuclei. Combining the initial state with hydrodynamic simulations, this enables us to predict how observables evolve when moving from RHIC to LHC energies.
nucl-thEPJ Web Conf.(2026)·1 citation
04
$Ξ N N$ three-baryon force from SU(3) chiral effective field theory: A femtoscopic study
Gen Uratsu🇯🇵 · Tokuro Fukui🇯🇵 · Kazuyuki Ogata🇯🇵
Background: The development of SU(3) chiral effective field theory has opened the way to a systematic exploration of three-baryon forces (3BFs), a key ingredient in hypernuclear and dense matter physics. However, $Ξ N N$ 3BF based on SU(3) chiral EFT has not been studied until now. Purpose: We apply SU(3) chiral EFT to derive $Ξ N N$ potentials in momentum space. Then, we investigate how the $Ξ N N$ 3BF affects the correlation function of deuteron-- $Ξ^{-}$ pair created through heavy-ion collisions. Methods: To reduce the number of low-energy constants involved in the $Ξ N N$ potentials, we employ the decuplet saturation approximation, by which only two of them remain unconstrained. The deuteron-- $Ξ^{-}$ scattering is treated as an effective two-body problem with the $Ξ N N$ 3BF incorporated into the potential between the deuteron and $Ξ^{-}$ . Results: We found that the effect of the $Ξ N N$ 3BF on the deuteron-- $Ξ^{-}$ correlation function is at most about 4\%. This small effect is not primarily due to the loosely-bound nature of the deuteron. Instead, this is because the deuteron and $Ξ^{-}$ interact with each other mainly at low momentum, corresponding to peripheral scattering, where the influence of the $Ξ N N$ 3BF is limited. Conclusions: Since the correlation function shows limited sensitivity to the short-range 3BF, complementary approaches may be necessary.
nucl-thhep-phnucl-exPRC(2026)·0 citations
05
Medium effects on the electromagnetic form factors of the $ρ$ meson
Parada T. P. Hutauruk🇰🇷 · Terry Mart🇮🇩 · Kazuo Tsushima🇧🇷
The dynamics of partons inside the light $ρ$ meson is found to be essential for its properties and internal structure, both in free space and in the nuclear medium. In this paper, we systematically investigate the in-medium structure changes of $ρ^{+}$ mesons within the covariant Nambu-Jona-Lasinio (NJL) model, utilizing the Schwinger proper-time regularization scheme. We solve the Bethe-Salpeter equations to guarantee the bound meson-state condition. At the quark level, the nuclear medium effects are also derived within the same NJL model to maintain a consistent approach with the in-medium $ρ^{+}$ meson electromagnetic form factors. To this end, we analyze the spacelike electromagnetic form factors of the $ρ^{+}$ meson in free space and in a nuclear medium. We find that the charge radius and quadrupole moment of the $ρ^{+}$ meson increase with increasing nuclear matter density, while the magnetic moment decreases, in agreement with the existing previous theoretical predictions. The enhancement of the $ρ^{+}$ meson charge radius at normal density relative to that in free space is about 11\% (0.08 fm), while the reduction of $ρ^{+}$ meson magnetic moment is about 8\% (0.20 $μ_{N}$ ). Our predictions for the charge radius, magnetic moment, and quadrupole moment of the $ρ^{+}$ meson in both free space and nuclear medium, remain challenging to be verified experimentally.
nucl-thhep-phPRD(2025)·7 citations
06
Bottomonium transport in a strongly coupled quark-gluon plasma
Biaogang Wu🇺🇸 · Ralf Rapp🇺🇸
Quarkonium production in high-energy heavy-ion collisions remains a key probe of the quark-gluon plasma formed in these reactions, but the development of a fully integrated nonperturbative approach remains a challenge. Toward this end, we set up a semiclassical transport approach that combines nonperturbative reaction rates rooted in lattice-constrained $T$ -matrix interactions with a viscous hydrodynamic medium evolution. Bottomonium suppression is computed along trajectories in the hydrodynamic evolution while regeneration is evaluated via a rate equation extended to a medium with spatial gradients. The much larger reaction rates compared to previous calculations markedly enhance both dissociation and regeneration processes. This, in particular, requires a reliable assessment of bottomonium equilibrium limits and of the non-thermal distributions of the bottom quarks transported through the expanding medium. Within current uncertainties our approach can describe the centrality dependence of bottomonium yields measured in Pb-Pb ( $s_{_{NN}}$ =5.02\,TeV) collisions at the LHC, while discrepancies are found at large transverse momenta.
nucl-thPLB(2026)·7 citations
07
Far from equilibrium attractors in phase space
Michał Spaliński🇫🇮
The emergence of far from equilibrium, prehydrodynamic attractors is an important feature of boost-invariant flow in models of relativistic fluid dynamics, as well as in some microscopic theories. Originally, these attractors were defined in terms of attractor solutions, using a partial decoupling of the equations of motion that relied on using special variables. Reliance on such a decoupling restricts the class of systems that can be analysed. Instead of introducing special variables, here we directly leverage the singularity of the evolution equations at early proper time. This singularity is a consequence of boost invariance, which should be regarded as crucial physical input stemming from fundamental properties of particle production in QCD. We posit that it provides initial conditions which determine the attractor hypersurface in phase space, irrespective of whether the evolution equations can be partially decoupled or not. We validate this in a case where the equations of motion cannot be decoupled but the attractor can still be identified and governs the behaviour of generic solutions in a similar way to what happens in cases where attractor solutions exist.
nucl-th5 citations
08
Signals for fluctuating constituent numbers in small systems
Andreas Kirchner🇺🇸 · Steffen A. Bass🇺🇸
We propose an extension of the initial condition model TRENTo for sampling the number of partons inside the nucleons that participate in a heavy-ion collision. This sampling method is based on parton distribution functions (PDFs) and therefore has a natural dependence on the momentum transferred in the collision and the scale being probed during the collision. We examine the resulting distributions and their dependence on the momentum transfer. Additionally, we explore the sensitivity of different observables on the number of partons using the TRENTo framework and the estimators available therein for final-state observables.
↳ hep-phnucl-th1 citation
09
Electromagnetic properties of heavy-light mesons
A. S. Miramontes🇪🇸 · J. Papavassiliou🇪🇸 · J. M. Pawlowski🇩🇪
Within the Bethe-Salpeter framework, we present a computation of space-like electromagnetic form factors for pseudoscalar mesons, including light and heavy-light systems. Our approach employs a flavour-dependent variation of the standard Taylor effective charge, which contains key contributions from the quark-gluon vertices. This effective interaction is a common ingredient of all relevant dynamical equations, and accommodates the crucial mass differences between the various quark flavours. Particular attention is paid to the nonperturbative determination of the quark-photon vertex. The computed electromagnetic form factors for the pion and the kaon mesons show excellent agreement with experimental determinations. In addition, the predictions for the charge radii of heavy-light systems are in overall good agreement with lattice QCD.
↳ hep-phhep-latnucl-thEPJC(2025)·10 citations
10
The (3+1)D structure of the dilute Glasma
Andreas Ipp🇦🇹 · Markus Leuthner🇦🇹 · David I. Müller🇦🇹 · Sören Schlichting🇩🇪 · Kayran Schmidt🇦🇹 · Pragya Singh🇫🇮
We study the (3+1)D structure of the Glasma in the dilute approximation, which allows us to describe the longitudinal dynamics that arise from the three-dimensional nuclear structure. We employ a nuclear model with tunable longitudinal and transverse fluctuation scales that generalizes the McLerran-Venugopalan model. We discuss the longitudinal profiles of the energy-momentum tensor and the transverse structure of the local rest frame energy density.
↳ hep-phnucl-thEPJ Web Conf.(2026)·1 citation
11
Updated Astrophysical Equation-of-State Constraints on the Color-Superconducting Gap
Aleksi Kurkela🇳🇴 · Krishna Rajagopal🇺🇸 · Rachel Steinhorst🇺🇸
We summarize and update using new NICER measurements the results of arXiv:2401.16253, in which we used various astrophysical neutron-star observations to set an upper bound on the CFL color-superconducting gap in a range of baryon chemical potentials $μ_{B} \in [2.1, 3.2]$ , above those reached within neutron stars. We also corroborate the ``reasonable" constraint from arXiv:2401.16253 on the maximum value of the color-superconducting gap by performing a new Bayesian analysis using a prior that extends a two-segment Gaussian process connecting the whole density range between CEFT and pQCD.
↳ hep-phastro-ph.HEnucl-thEPJ Web Conf.(2026)·1 citation
12
Impact of new results from the ultraperipheral collision on modeling the proton and neutron emission in photon-induced nuclear processes
P. Jucha🇵🇱 · K. Mazurek🇵🇱 · A. Szczurek🇵🇱 · K. Pysz🇵🇱
The ultrarelativistic collisions of heavy ions provide rich spectrum of possibilities to discuss the response of the nucleus to photons. Newly published neutron and proton multiplicities measured in the ALICE experiment in ultraperipheral collisions allow investigating the influence of the electromagnetic fields on colliding nuclei for the $^{208}$ Pb+ $^{208}$ Pb at $s_{N N}$ =5.02~TeV. The theoretical predictions are done within hybrid model including equivalent photon approximations (EPA), GiBUU modeling of pre-equilibrium processes and generation of the exited nuclear remnants, which decay is modeled by statistical approach: GEM2 or GEMINI++. The cross-sections of the mass-charge distributions of nuclear remnants as well as the neutron, proton and other charged particle multiplicities are estimated. We concentrate on production of protons and isotopes coming from the electromagnetic dissociation. Special attention is devoted to emission of a single proton. The cross section for $1 p$ emission is very close to maximal available one based on reactions of photon with individual nucleons. Our pre-equilibrium processes explain simultaneously the tail of neutron energy distributions in the nuclear rest frame observed in $γ + A$ collisions.
↳ hep-phnucl-thPRC(2026)·0 citations
13
Curvilinear coordinates and curvature in radiative transport
Johannes Krotz · Ryan G. McClarren
We derive a general expression for the streaming term in radiative transport equa- tions and other transport problems when formulated in curvilinear coordinates, emphasizing coordinate systems adapted to the geometry of the domain and the directional dependence of particle transport. By parametrizing the angular vari- able using a local orthonormal frame, we express directional derivatives in terms of curvature-related quantities that reflect the geometry of underlying spatial man- ifolds. Our formulation highlights how the interaction between coordinate choices and curvature influences the streaming operator, offering geometric interpretations of its components. The resulting framework offers intuitive insight into when and how angular dependence can be simplified and may guide the selection of coordinate systems that balance analytical tractability and computational efficiency.
↳ math.NAcs.NAmath.APnucl-th0 citations
14
Deep learning for jet modification in the presence of the QGP background
Ran Li🇨🇳 · Yi-Lun Du🇨🇳 · Shanshan Cao🇨🇳
Jet interactions with the color-deconfined QCD medium in relativistic heavy-ion collisions are conventionally assessed by measuring the modification of the distributions of jet observables with respect to their baselines in proton-proton collisions. Deep learning methods enable per-jet evaluation of these modifications, enhancing the use of jets as precision probes of the nuclear medium. In this work, we predict the jet-by-jet fractional energy loss $χ$ for jets evolving through a quark-gluon plasma (QGP) medium using a Linear Boltzmann Transport (LBT) model. To approximate realistic experimental conditions, we embed medium-modified jets in a thermal background and apply Constituent Subtraction for background removal. Two network architectures are studied: convolutional neural networks (CNNs) using jet images, and dynamic graph convolutional neural networks (DGCNNs) using particle clouds. We find that CNNs achieve accurate predictions for background-free jets but degrade in the presence of the QGP background and remain below the background-free baseline even after background subtraction. In contrast, DGCNNs applied to background-subtracted particle clouds maintain high accuracy across the entire $χ$ range, demonstrating the advantage of point-cloud-based graph neural networks that exploit full jet structure under realistic conditions.
↳ hep-phhep-exnucl-exnucl-thPRC(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE