Nuclear Theory·nucl-th

Friday·March 6, 2026

10 papers—5 primary·5 cross-listed

01
Coupled charm and charmonium transport in a strongly coupled quark-gluon plasma
Kaiyu Fu🇺🇸 · Biaogang Wu🇺🇸 · Ralf Rapp🇺🇸
The quark-gluon plasma (QGP) is a strongly coupled medium in which both open and hidden charm particles experience substantial nonperturbative interactions. This poses a major challenge for a quantitative description of charmonium transport in ultra-relativistic heavy-ion collisions, as it requires a mutually consistent treatment of pertinent transport coefficients. In this work, we present a coupled charm-charmonium transport framework for a strongly coupled QGP based on thermodynamic $T$ -matrix interactions with recent constraints from Wilson-line correlators (WLCs) computed in lattice QCD. For the first time, the same underlying heavy-light interactions and in-medium spectral functions are used to self-consistently evaluate charm-quark diffusion and charmonium kinetics. In particular, the charmonium equilibrium limit, a critical transport parameter for regeneration, is evaluated in the presence of broad spectral functions. Charm-quark diffusion is simulated via Langevin dynamics and coupled to a Boltzmann equation for charmonium dissociation and regeneration. The equilibrium limit of the statistical model is recovered once charm quarks thermalize, and its extension to describe off-equilibrium is constructed. Preliminary applications to charmonium observables in Pb--Pb collisions at the LHC capture the measured centrality and momentum dependence fairly well.
nucl-thEPJA(2026)·1 citation
02
Single-Particle Resonant States in Relativistic Hartree-Fock Theory: A Green's Function Approach
Wei Gao · Ting Ting Sun · Wen Hui Long
Relativistic Hartree-Fock theory is combined with the Green's function method in coordinate space to study both single-particle bound and resonant states within a unified framework. Within this approach, single-particle resonance energies and widths are unambiguously extracted from the density of states, and the influence of the Coulomb exchange effects on proton resonances in $N = 82$ isotones are systematically examined. It is found that the exact treatment of Coulomb exchange terms reduces proton resonance energies of approximate $0.09 \sim 0.21$ MeV, a significantly smaller effect than that obtained from the phenomenological treatment. Moreover, except for rather narrow resonances, the proton resonance widths are visibly reduced by the Coulomb exchange terms, also being much less pronounced than the phenomenological approach. Notably, clear shell effects are observed in the isotonic evolutions of the resonance energy reductions for specific resonances. All these highlight the necessity of a microscopical and exact treatment of the Coulomb exchange terms.
nucl-thCPC(2026)·0 citations
03
Bayesian Learning of (n,p) Reaction Cross Sections with Quantified Uncertainties
Arunabha Saha · Songshaptak De
Accurate neutron-induced $(n, p)$ reaction cross sections are essential for applications in nuclear energy, radionuclide production, materials studies, and nuclear astrophysics. However, experimental data remain sparse for many isotopes, and evaluated nuclear data libraries can show systematic deviations from available measurements. We develop a Bayesian neural network (BNN) residual learning model, denoted \texttt{BNN-R5}, to improve $(n, p)$ reaction cross-section predictions. The model uses five physically motivated nuclear descriptors and does not employ experimental or evaluated cross-section values as input features. Rather than predicting the cross sections directly, \texttt{BNN-R5} learns the log-space residual between the evaluated TENDL-2023 data and experimental measurements, thereby providing a data-driven correction to the evaluated library. The model is trained using stochastic variational inference, which provides predictive mean values together with Bayesian uncertainty estimates. Across a broad range of target nuclei, the corrected cross sections generally show improved agreement with experimental data and outperform the original TENDL-2023 evaluations. Feature-importance analysis using SHapley Additive exPlanations (SHAP) identifies the pairing term $δ$ as the most influential descriptor, followed by the excitation-energy variable $ln (Δ E)$ and the neutron number $N$ , while the proton number $Z$ has the smallest overall influence. These results demonstrate that Bayesian residual learning provides a robust and interpretable framework for improving evaluated nuclear data and predicting reaction cross sections in data-sparse regions of the nuclear chart.
nucl-th0 citations
04
Six- $α$ cluster Bose-Einstein condensation and supersolid $^{12}$ C( $0_{2}^{+})$ + $^{12}$ C( $0_{2}^{+})$ molecular structure in $^{24}$ Mg
S. Ohkubo · J. Takahashi · Y. Yamanaka
We show for the first time that the low-spin ( $J \leq 4^{+}$ ) six- $α$ condensate candidate states in $^{24}$ Mg, recently reported by Fujikawa et al. [Phys. Lett. B 848, 138384 (2024)], are well described by the superfluid $α$ -cluster model (SCM). This is achieved by a rigorous treatment of the Nambu-Goldstone (NG) zero mode as the order parameter of condensation in the finite six- $α$ system. We find that a roton rotational band with a large moment of inertia is built on the first excited NG $0^{+}$ state, analogous to the roton bands observed in three-, four-, and five- $α$ condensates in $^{12}$ C, $^{16}$ O, and $^{20}$ Ne, respectively. Remarkably, our calculated roton band reproduces the well-known molecular resonance with a $^{12}$ C( $0_{2}^{+}$ )+ $^{12}$ C( $0_{2}^{+}$ ) structure ( $1 6^{+}$ ) observed at $E_{c.m.} = 32.5$ MeV in inelastic $^{12}$ C+ $^{12}$ C scattering. This result provides a unified description of both the low-spin six- $α$ condensate states and the high-spin $^{12}$ C( $0_{2}^{+}$ )+ $^{12}$ C( $0_{2}^{+}$ ) molecular resonance. Analysis of the wave functions reveals a large overlap between the SCM states and a geometrical $^{12}$ C( $0_{2}^{+}$ )+ $^{12}$ C( $0_{2}^{+}$ ) configuration. This dual nature -the coexistence of superfluidity and crystallinity- identifies these states as a signature of a supersolid.
nucl-thEPJA(2026)·0 citations
05
Emergence of the geometric contribution to the superfluid density in the inner crust of neutron stars
Giorgio Almirante🇫🇷
The geometric contribution to the superfluid density has been found to be of great importance in the inner crust of neutron stars. In this work we clarify how this contribution arises in the context of a band theory for neutrons. Specifically, we derive the dependence of the superfluid density on the magnitude of the pairing gap when the system has many bands cutting the Fermi energy, as it is the case for the neutrons in the inner crust. Also, in the perturbation theory framework, we find that it is essential to account for the corrections to the (Bogoliubov) quasi-particle states in order to get the geometric contribution. Accounting only for the corrections to the (Hartree-Fock) single-particle states leads to the conventional contribution only.
nucl-thcond-mat.quant-gasParticles(2026)·1 citation
06
The MexNICA Collaboration in the MPD-NICA Experiment at JINR: Experimental and Theoretical Achievements
Alfredo Raya · Mauricio Alvarado · Juan Anzúrez · Alejandro Ayala · Wolfgang Bietenholz · Salomón Borjas García · Eleazar Cuautle · Pedro E. García González · Irving Iván Gaspar Gregorio · Isabel Domínguez · Luis Alberto Hernández · Maribel Herrera and 12 other authors
The MexNICA Collaboration coordinates the activities of Mexican scientists, engineers, postdoctoral fellows and students in the Multi-Purpose Detector experiment at the Nuclotron-based Ion Collider fAcility of the Joint Institute for Nuclear Research in Dubna, Russia. Established in 2016, the collaboration brings together five Mexican institutions whose contributions span detector development as well phenomenological and theoretical studies, including modeling by means of Monte Carlo simulations. This work summarizes the main achievements of MexNICA, consisting of the development of the miniBeBe trigger detector as well of results of phenomenological investigations of the baryon-rich region in the QCD phase diagram accessible at NICA energies, and theoretical advances based on lattice QCD and effective models.
↳ nucl-exhep-lathep-phhep-th+20 citations
07
Exploring Nucleon Structure and the Proton Mass Problem through Holographic QCD
Jiali Deng🇨🇳 · Defu Hou🇨🇳
Understanding the internal structure of the proton-including the distributions of quarks and gluons and their contributions to proton properties such as mass-remains a central challenge in quantum chromodynamics (QCD). While quark generalized parton distributions (GPDs) have been studied extensively, a unified approach that simultaneously extracts quark parton distribution functions (PDFs), gravitational form factors (GFFs), and gluon GPDs from experimental constraints is still lacking. Moreover, the role of gluons in proton mass generation, particularly through the trace anomaly mechanism, requires deeper theoretical and phenomenological exploration. In this study, we begin by extracting quark GPDs in protons using a parameterization method based on the electromagnetic form factors provided by Light-Front Holographic QCD (LFHQCD), from which we derive both quark PDFs and their GFFs. We then extend this approach to model gluon GPDs. Our calculations show consistency with experimental data and lattice QCD results and successfully reproduce soft Pomeron behavior. Furthermore, we investigate near-threshold $J / ψ$ production using gauge/string duality to quantify the contribution of the trace anomaly to the proton mass. Our results demonstrate that the parameterization method provides a consistent framework for describing both quark and gluon structure, bridging GPDs, PDFs, and GFFs. The analysis of $J / ψ$ production confirms that the trace anomaly contributes significantly ( $\sim 24%$ ) to the proton mass, with the calculated cross-section dependence on momentum transfer $t$ in agreement with experimental observations. This work advances the understanding of proton structure by integrating quark and gluon degrees of freedom and elucidating the origin of proton mass within QCD.
↳ hep-phnucl-thPRD(2026)·4 citations
08
Simulating Lattice Gauge Theories with Virtual Rishons
David Rogerson🇺🇸 · João Barata🇨🇭 · Robert M. Konik🇺🇸 · Raju Venugopalan🇺🇸 · Ananda Roy🇺🇸
Classical tensor network and hybrid quantum-classical algorithms are promising candidates for the investigation of real-time properties of lattice gauge theories. We develop here a novel framework which enforces gauge symmetry via a quantum-link virtual rishon representation applied at intermediate steps. Crucially, the gauge and matter degrees of freedom are dynamical variables encoded in terms of qubits, enabling analysis of gauge theories in $d + 1$ spacetime dimensions. We benchmark this framework in a U(1) gauge theory with and without matter fields. For $d = 1$ , the multi-flavor Schwinger model with $1 \leq N_{f} \leq 3$ flavors is analyzed for arbitrary boundary conditions and nonzero topological angle, capturing signatures of the underlying Wess-Zumino-Witten conformal field theory. For $d = 2$ , we extract the confining string tension in close agreement with continuum expectations. These results establish the virtual rishon framework as a scalable and robust approach for the simulation of lattice gauge theories using both classical tensor networks as well as near-term quantum hardware.
↳ hep-thcond-mat.str-elhep-latnucl-th+12 citations
09
Axial-vector neutral-current measurements in coherent elastic neutrino-nucleus scattering experiments
D. Aristizabal Sierra🇨🇱 · Pablo M. Candela🇪🇸 · Valentina De Romeri🇪🇸 · Dimitrios K. Papoulias🇪🇸 · Laura Trincado S🇨🇱
Coherent elastic neutrino-nucleus scattering (CE $ν$ NS) is predominantly governed by vector neutral-current interactions, with subleading contributions arising from the axial current in nuclei with non-zero ground-state spin. Experimentally, the extraction of axial-current contributions has been so far of little interest, mainly because of the challenges its measurement entail. In this work, we investigate the relative size of the vector and axial components for target materials currently employed by the neutrino and dark matter experimental communities. We identify fluorine-based compounds as the most promising targets for probing the axial-current event rate. Among them, octafluoropropane ( $C_{3} F_{8}$ ) emerges as a particularly suitable candidate, given its widespread use in spin-dependent dark matter searches and its relevance for upcoming dedicated CE $ν$ NS experiments. Considering both pion decay-at-rest and reactor neutrino fluxes, we show that such measurements can allow an indirect determination of the axial coupling at the $\sim 10%$ level, depending on flux uncertainties and detector thresholds. We further emphasize that measurements of the axial current will allow to probe spin-dependent new physics scenarios through CE $ν$ NS.
↳ hep-phhep-exnucl-exnucl-thPRD(2026)·3 citations
10
Exploring $T_{ΥΥ}$ tetraquark candidates in a coupled-channels formalism
P.G. Ortega🇪🇸 · D.R. Entem🇪🇸 · F. Fernandez🇪🇸 · J. Segovia🇪🇸
We investigate the spectrum of $T_{ΥΥ}$ tetraquark candidates within a coupled-channels framework. The analysis includes all $L \leq 2$ combinations of $Υ (1 S)$ , $Υ (2 S)$ , $η_{b} (1 S)$ , and $η_{b} (2 S)$ in the $J^{P} = 0^{\pm}, 1^{\pm}, 2^{\pm}$ sectors. The meson-meson interaction is derived from an underlying constituent quark model through the resonating group method, and the properties of the states are obtained from poles of the scattering matrix. We find a rich spectrum of resonant, and virtual, states distributed between the $η_{b} (1 S) η_{b} (1 S)$ and $Υ (2 S) Υ (2 S)$ thresholds. The pattern of poles exhibits approximate heavy-quark spin symmetry multiplets. Several states are dominated by a single channel and can be associated with threshold-driven structures, while higher-mass resonances show sizable mixing among channels involving radially excited bottomonia. The predicted widths range from tens to several hundred MeV. Branching ratios indicate that many states couple predominantly to final states with at least one excited bottomonium, whereas only a subset of the spectrum is expected to be visible in the $η_{b} (1 S) η_{b} (1 S)$ , $η_{b} (1 S) Υ (1 S)$ and $Υ (1 S) Υ (1 S)$ channels. These results provide quantitative guidance for experimental searches of fully heavy tetraquarks and offer a test of coupled-channel dynamics and heavy-quark spin symmetry in the $bb b ˉ b ˉ$ sector.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE