Nuclear Theory·nucl-th

Monday·February 9, 2026

9 papers—4 primary·5 cross-listed

01
"Observations on the possible electromagnetic nature of nucleon interactions and pions" -- historical manuscript from 1969 by B. W. Ninham and C. Pask
Mathias Boström🇵🇱 · Drew F. Parsons🇮🇹
This manuscript presents an historical perspective prepared by Barry Ninham and Colin Pask in 1969 on the connection between quantum electrodynamics theory and nucleon interactions. A new theory of strong interactions based on electromagnetic considerations is proposed. Energy and force range magnitudes are correctly given. A new theory of the pion emerges and the pion mass and lifetime are calculated. No strong interaction coupling constant is required.
nucl-thcond-mat.mtrl-scihep-phphysics.hist-phSubstantia, 2025·1 citation
02
Fixed-energy inverse scattering with radial basis function neural networks and its application to neutron-alpha interactions
Gábor Balassa
This paper proposes a data-driven method to solve the fixed-energy inverse scattering problem for radially symmetric potentials using radial basis function (RBF) neural networks in an open-loop control system. The method estimates the scattering potentials in the Fourier domain by training an appropriate number of RBF networks, while the control step is carried out in the coordinate space by using the measured phase shifts as control parameters. The system is trained by both finite and singular input potentials and is capable of modeling a great variety of scattering events. The method is applied to neutron-alpha scattering at 10 MeV incident neutron energy, where the underlying central part of the potential is estimated by using the measured l = 0, 1, 2 phase shifts as inputs. The obtained potential is physically sensible, and the recalculated phase shifts are within a few percent relative error.
nucl-thhep-phPTEP(2023)·6 citations
03
Bayesian Constraints on the Neutron Star Equation of State with a Smooth Hadron-Quark Crossover
Xavier Grundler🇺🇸 · Bao-An Li🇺🇸
We perform a Bayesian inference of the dense-matter equation of state (EOS) within a unified framework that incorporates hadronic matter, quark matter, and a smooth hadron-to-quark crossover. The EOS is constrained using physical consistency conditions, gravitational wave data from GW170817, NICER mass versus radius measurements, and hypothetical future high-precision radius observations. In contrast to most previous studies that assume a sharp first-order phase transition or fix part of the EOS, we simultaneously infer hadronic, quark, and crossover parameters within a single statistical framework. We find that current observations strongly constrain the density dependence of the nuclear symmetry energy, particularly its slope and curvature. In contrast, the highest density hadronic parameters and quark-matter properties remain only weakly constrained. We further show that the trace anomaly exhibits a remarkably universal behavior across the accepted EOS ensemble and remains largely insensitive to current observational constraints. This indicates that the present data primarily probe the low to intermediate density EOS. At the same time, robust inference of quark matter and genuinely high-density physics will require next-generation precision radius measurements or complementary observables.
nucl-thastro-ph.HEhep-phhep-th+1PRD(2026)·3 citations
04
Many-body effects on dense matter with hyperons at finite temperature
Rafael Bán Jacobsen · Ricardo Luciano Sonego Farias · Veronica Dexheimer
In this work, we present the first extension of the Many-Body Forces (MBF) Model to finite temperature. The MBF Model describes nuclear matter in a relativistic quantum hadrodynamics formalism that takes many-body forces into account through a field dependence of the nuclear interaction coupling constants. Assuming nuclear matter to be charge neutral, beta-equilibrated, and populated by the baryon octet, electrons, and muons, we explore the parameters of the model, three different hyperon coupling schemes (also introduced here for the first time in MBF), and temperature effects to describe basic properties of nuclear matter, including the speed of sound, compressibility, and adiabatic index. We also investigate the mass-radius relation of compact stars by solving the Tolman-Oppenheimer-Volkoff equations at zero and finite temperature, including scenarios with fixed entropy per baryon. Our original results at finite temperature open the path to a new description of proto-neutron stars.
nucl-thastro-ph.HEhep-th0 citations
05
Holographic Charged Transport with Higher Derivatives
Alex Buchel🇨🇦 · Sera Cremonini🇺🇸 · Mohammad Moezzi🇺🇸 · George Tringas🇺🇸
We compute the first-order hydrodynamic transport coefficients (shear viscosity $η$ , bulk viscosity $ζ$ , and charge conductivity $σ$ ) for a broad class of strongly coupled, four-dimensional charged relativistic gauge theory plasma with holographic gravitational duals containing higher-derivative corrections. The landscape of our holographic models captures non-conformal gauge theories with an arbitrary number of relevant coupling constants and a general scalar potential in the gravitational dual, allowing for a systematic exploration of charged transport along generic holographic RG flows. The leading-order higher-derivative corrections probe gauge theories with non-equal central charges $c \neq = a$ at the ultraviolet fixed point, and enable the engineering of diverse temperature and charge density profiles for the viscosities and the conductivity. Our results establish the membrane paradigm in higher-derivative holographic models: all the transport coefficients are extracted from the black brane horizon values of the gravitational scalars, and various functions defining the gravitational holographic dual.
↳ hep-thcond-mat.str-elhep-phnucl-thJHEP(2026)·3 citations
06
How Neutron Star Observations Point Towards Exotic Matter: Existing Explanations and a Prospective Proposal
Mauro Mariani🇦🇷 · Ignacio F. Ranea-Sandoval🇦🇷
Multi-messenger astronomical observations of neutron stars, together with more precise calculations and constraints coming from dense matter microphysics, are generating tension with regard to equations of state models used to describe neutron star cores. Assuming an abrupt first-order phase transition with a slow conversion speed between phases, we propose different slow stable hybrid star configurations aiming to reconcile all current constraints simultaneously; within this framework, we also introduce a novel non-CSS parametrization to the quark matter equation of state and discuss its strengths and limitations. We analyze our model results in conjunction with a review of other relevant theoretical possibilities existing in the literature. We found that modern neutron star observations seem to favor the existence of some type of exotic matter in the neutron star cores; in particular, our slow stable hybrid star scenario remains a proposal capable of satisfying these constraints. However, due both to the existing skepticism regarding some of the adopted hypotheses in most extreme neutron star measurements and to the precise adjustment needed for the equation-of-state parameters, significant tension and open questions remain.
↳ astro-ph.HEnucl-thSymmetry(2026)·3 citations
07
Quasi-elastic scattering for the nuclear ground state structure: An intriguing case of $^{30}$ Si
Y. K. Gupta🇮🇳 · B. Maheshwari🇫🇷 · G. K. Prajapati🇮🇳 · A. K. Jain · K. Hagino🇯🇵 · B. N. Joshi🇮🇳 · A. Pal🇮🇳 · N. Sirswal🇮🇳 · Pawan Singh🇮🇳 · S. Dubey🇮🇳 · V. V. Desai🇮🇳 · V. Ranga🇮🇳 and 8 other authors
Quasi-elastic (QEL) scattering measurements have been performed using the $^{28, 30}$ Si projectiles off the $^{90}$ Zr target at energies around the Coulomb barrier. Coupled-channels (CC) calculations were carried out in a large parameter space of quadrupole and hexadecapole deformations for the N=Z, $^{28}$ Si and N=Z+2, $^{30}$ Si nuclei. $^{28}$ Si at the N=Z line is observed to be uniquely oblate shaped in its ground state. In contrast, for $^{30}$ Si with just two additional neutrons -- oblate, prolate, and spherical CC descriptions are equally compatible with the measurements. To further investigate the nuclear structure evolution with varying neutron number, shell-model calculations were performed. These calculations reveal a sudden change in the nuclear structure aspects at $^{30}$ Si in going from $^{28}$ Si to $^{30}$ Si. Combined reaction and structure analyses consistently indicate that $^{30}$ Si does not possess a well-defined intrinsic shape, and it is a potential candidate for ``shape fluctuations" in its ground state.
↳ nucl-exnucl-thPLB(2026)·0 citations
08
Physics of strong electromagnetic fields in relativistic heavy-ion collisions
Koichi Hattori🇨🇳
I discuss several roles of the strong electromagnetic fields created by relativistic heavy-ion collisions. These phenomena call for theoretical and experimental developments to understand dynamics of quark-gluon plasma (QGP) as well as purely electromagnetic processes in the ultraperipheral collisions.
↳ hep-phnucl-thJ.Subatomic Part.Cosmol.(2026)·0 citations
09
Proton-Size Resolution of the Hyperfine Puzzle in Hydrogen
Gerald A. Miller
Baym and Farrar (arXiv:2601.02300v1) have recently pointed out a puzzle in understanding the role of the hyperfine interaction in the ground state of a hydrogen atom. If one uses a variational wave function in which the Bohr radius, $a_{0}$ is replaced by a variational radius parameter, $R$ , first-order perturbation theory can give a contribution to the energy proportional to $- 1/ R^{3}$ . This raises the question of why the hyperfine interaction does not lead to collapse of hydrogen. I show that including the effects of the non-zero size of the proton leads to a resolution of the puzzle such that the variational procedure yields a value of $R$ that is indistinguishable from $a_{0}$ .
↳ physics.atom-phhep-phnucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE