Nuclear Theory·nucl-th

Tuesday·June 10, 2025

15 papers—4 primary·11 cross-listed

01
Charge symmetry breaking effects of $ω$ - $ρ^{0}$ mixing in relativistic mean-field model
Yusuke Tanimura🇰🇷 · Tomoya Naito🇯🇵 · Hiroyuki Sagawa🇯🇵 · Myung-Ki Cheoun🇰🇷
We present a relativistic mean-field model that incorporates charge symmetry breaking (CSB) of nuclear force via $ω$ - $ρ^{0}$ meson mixing, along with corrections to the electromagnetic interaction including the nucleon form factors, first-order vacuum polarization, and Coulomb exchange and pairing terms. The model parameters are refitted using the mass differences of $T = 1/2$ mirror nuclei and ground-state properties of magic nuclei, yielding DD-ME-CSB parameter set. The DD-ME-CSB parameter set reproduces the mass differences of mirror nuclei reasonably well up to $T = 2$ , demonstrating the importance of $ω$ - $ρ^{0}$ mixing. A connection of the present model to a Skyrme-type CSB interaction is also established through a gradient expansion of the energy density functional.
nucl-thEPJA(2025)·2 citations
02
Effects of vibration and rigidity modes of motion on the spectral statistics of spherical nuclei
H. Sabri · A. Hosseinnezhad
In this paper, we investigated the effects of \b{eta}-vibration and \b{eta}-rigidity on the energy levels from the viewpoint of statistical fluctuations of nuclear systems. To this aim, a parameter-free collective solution of the Bohr Hamiltonian in the five-dimensional harmonic oscillator potential with a linear energy dependence and an asymptotic limit of the slope are used to determine all of the observed normal states in even-even nuclei with ~ 2.00 - 2.15 ratio in the A ~ 90 -140 mass region. Different sequences are prepared of the energy levels, both experimental values and theoretical predictions, which are categorized as their spin-parity, \b{eta} oscillator quanta, and seniority numbers and analyzed in the framework of random matrix theory to show their statistical situation in comparison with regular and correlated limits. Also, up to 2226 levels with the same 2+ spin-parity assignment are determined for different systems in which the stiffness parameter for them changed between a = 0 and a =1 limits and then analyzed in the same process. The results showed a transition between correlated behavior and regularity when the rigidity increased in considered systems. Also, there are apparent relations between the chaocity degrees of considered sequences and the considered criteria for classifications.
nucl-th0 citations
03
What is the Quark-Gluon Plasma made of?
Berndt Müller🇺🇸
This article surveys our present understanding of the internal structure of the fully developed quark-gluon plasma at temperatures outside the crossover region. The theoretical part of the review covers perturbative and nonperturbative approaches to quark-gluon plasma structure, in particular, hard-thermal loop effective theory, lattice QCD and the functional renormalization group. The phenomenological part of the review scrutinizes the information that has been derived from bulk observables and hard probes in relativistic heavy ion collisions in terms of how it informs our knowledge about the structure of the quark-gluon plasma. The final section lists possible avenues for future progress.
nucl-thhep-ph3 citations
04
Dependence of angular momentum of fission fragments on total kinetic energy in spontaneous fission of $^{252}$ Cf
A. Rahmatinejad (1) · T. M. Shneidman (1) · G.G. Adamian (1) · N.V. Antonenko (1,2) ((1) Joint Institute for Nuclear Research, Russia, (2) Tomsk Polytechnic University, Russia)
A weak dependence of the angular momentum of $^{144}$ Ba fragments, produced in the spontaneous fission of $^{252}$ Cf, on the total kinetic energy (TKE) was recently observed \cite{Giha2025}. To investigate this phenomenon, we propose a model describing the evolution of the fissioning nucleus toward scission. The model assumes that after tunneling through the fission barrier, the nucleus can be represented by a superposition of dinuclear systems (DNS). We calculate main fission observables, including mass, TKE, and neutron multiplicity distributions, and compare them with experimental data. The angular motion in the DNS is treated quantum-mechanically, yielding the angular momentum distribution of DNS nuclei at scission configurations leading to $^{144}$ Ba fragments. Within this framework, we successfully reproduce and explain the experimentally observed dependence of the average angular momentum of $^{144}$ Ba on TKE.
nucl-thPRC(2025)·1 citation
05
Perturbative QCD reveals the softening of matter in the cores of massive neutron stars
Oleg Komoltsev🇳🇴
The cores of neutron stars (NSs) contain the densest matter in the universe. Rapid advancements in neutron-star observations allow unprecedented empirical access to cold, ultra-dense Quantum Chromodynamics (QCD) matter. The combination of these observations with theoretical calculations has revealed previously inaccessible features of the equation of state (EoS) and the QCD phase diagram. In this thesis, I demonstrate how perturbative-QCD calculations at asymptotically high baryon densities provide robust constraints on the EoS at neutron-star densities. The method for constraint propagation is based solely on thermodynamical causality, stability, and consistency of the EoS. By constructing a large ensemble of EoSs using Gaussian processes regression and incorporating it into a Bayesian inference of EoS, I demonstrate that the novel pQCD constraints go beyond those obtained from current astrophysical observations alone, forcing the EoS to soften at the maximum densities of stable neutron stars. This softening of the EoS can be interpreted as an indication of approximate conformal symmetry restoration, a sign of a first-order phase transition (FOPT), or potentially both. I show that the conformal symmetry restoration is consistent with the hypothesis of quark matter cores inside the most massive NSs. Although current astrophysical data and theoretical inputs cannot definitively distinguish between the two scenarios, they slightly favor the occurrence of a phase transition of some kind - whether a crossover to quark matter or a destabilizing FOPT - in the cores of the most massive neutron stars.
↳ astro-ph.HEhep-phnucl-th2 citations
06
Universal Mass Equation for Equal-Quantum Excited-States Sets II
L. David Roper (VTech)🇺🇸 · Igor Strakovsky (GWU)🇺🇸
We extend our recent study of the universal mass equation for equal-quantum excited-states sets reported by Roper and Strakovsky~\cite{Roper:2024ovj}. The masses of twelve baryon sets and sixteen meson sets, with only two equal-quantum excited states in each set, using Breit-Wigner PDG2024 masses and their uncertainties at fixed $J^{P}$ for baryons and $J^{P C}$ for mesons, are fitted by a simple one-parameter logarithmic function, $M_{n} = α L n (n) + M_{1}$ , where $n$ is the level of radial excitation. Two accurate masses that start a set are used to calculate four higher masses in the set accurately. It is noted that $α$ values for $b b ˉ$ equal-quantum excited-states sets accurately lie on a straight line, whose line parameters can be used to calculate $α$ and predict higher mass states for $b b ˉ$ sets that have only one known member.
↳ hep-phhep-exnucl-exnucl-thEPJA(2025)·0 citations
07
Emergent Viscous Hydrodynamics From a Single Quantum Particle
Zhi-Li Zhou🇺🇸 · Mauricio Hippert🇧🇷 · Nicki Mullins🇺🇸 · Jorge Noronha🇺🇸
We investigate an explicit example of how spatial decoherence can lead to hydrodynamic behavior in the late-time, long-wavelength regime of open quantum systems. We focus on the case of a single non-relativistic quantum particle linearly coupled to a thermal bath of noninteracting harmonic oscillators at temperature $T$ , a la Caldeira and Leggett. Taking advantage of decoherence in the position representation, we expand the reduced density matrix in powers of the off-diagonal spatial components, so that high-order terms are suppressed at late times. Truncating the resulting power series at second order leads to a set of dissipative transient hydrodynamic equations similar to the non-relativistic limit of equations widely used in simulations of the quark-gluon plasma formed in ultrarelativistic heavy-ion collisions. Transport coefficients are directly determined by the damping constant $γ$ , which quantifies the influence of the environment. The asymptotic limit of our hydrodynamic equations reduces to the celebrated Navier-Stokes equations for a compressible fluid in the presence of a drag force. Our results shed new light on the onset of hydrodynamic behavior in open quantum systems where a system with few degrees of freedom is coupled to a large thermal environment.
↳ cond-mat.stat-mechhep-thnucl-thquant-phPRE(2026)·5 citations
08
New Types of Hydrogenlike matter Composed of Electron(s) and Meson(s)
Jun-Feng Wang🇨🇳 · Zi-Yue Cui🇨🇳 · Cheng-Qun Pang🇨🇳 · Zhi-Feng Sun🇨🇳
In the present work, we predict the existence of new types of hydrogenlike matter, including hydrogenlike atoms ( $π^{+} e^{-}$ , $K^{+} e^{-}$ , $D^{+} e^{-}$ ), hydrogenlike molecular ions ( $π^{+} π^{+} e^{-}$ , $K^{+} K^{+} e^{-}$ , $D^{+} D^{+} e^{-}$ ) and hydrogenlike molecules ( $π^{+} π^{+} e^{-} e^{-}$ , $K^{+} K^{+} e^{-} e^{-}$ , $D^{+} D^{+} e^{-} e^{-}$ ). By solving the Schrödinger equation, the binding energy of hydrogenlike atoms is obtained as $E_{n} = - \frac{1}{2 n ^{2}}$ . For hydrogenlike molecular ions and molecules, the variational method is employed to calculate the binding energies, i.e., $E_{+} = - 0.587$ and $E_{0} = - 1.139$ for hydrogenlike molecular ions and molecules, respectively. And the bond lengths for hydrogenlike molecular ions and molecules are also calculated, whose values are $2.003$ and $1.414$ , respectively. Here all the quantities are in atomic units for convenience. In addition, the strong interaction between the two constituent mesons is considered in our calculations, where we find that its influence on the hydrogenlike molecular ions and molecules can be neglected. Comparisons of hydrogenlike molecular ion and molecule with the systems governed by the strong interaction are made, which suggests the possible existence of doubly heavy triquark, hidden heavy-flavor tetraquarks and doubly heavy tetraquarks. Hopefully, these types of matter would be observed in the future with the improvement of accuracy in the high energy physical experiments.
↳ hep-phhep-exnucl-exnucl-thFew Body Syst.(2026)·0 citations
09
Dense matter in a holographic hard-wall model of QCD
Daisuke Fujii🇯🇵 · Atsushi Hosaka🇯🇵 · Akihiro Iwanaka🇯🇵 · Tadakatsu Sakai🇯🇵 · Motoi Tachibana🇯🇵
A deeper understanding of QCD matter at strong coupling remains challenging due to its non-perturbative nature. To this end, we study a two-flavor holographic hard-wall model to investigate the properties of QCD at finite-density and zero temperature with a nonvanishing quark mass. A dense matter phase is described by a classical solution of the equations of motion in a homogeneous Ansatz. We apply holographic renormalization to formulate the holographic dictionary that relates UV boundary data in the bulk with the physical quantities in QCD. We emphasize a role played by an IR boundary action on the hard-wall when analyzing the QCD phase structures in this holographic setup. It is found that a baryonic matter phase is manifested in this model with a high baryon number density and a nearly vanishing chiral condensate. We derive the equation of state for the resulting phase and use it to work out the mass-radius relation for neutron stars. We find that the maximum mass of neutron stars can exceed two solar masses for a wide range of free parameters in this model. We also comment on an alternative scenario about the phase structure such that the baryonic matter phase arises at a baryon number chemical potential greater than a critical value.
↳ hep-phhep-thnucl-thPRD(2026)·3 citations
10
Unveiling the role of vector potential in the Aharonov-Bohm effect
Masashi Wakamatsu
The most popular interpretation of the Aharonov-Bohm (AB) effect is that the electromagnetic potential locally affects the complex phase of a charged particle's wave function in the magnetic field free region. However, since the vector potential is a gauge-variant quantity, not a few researchers suspect that it is just a convenient tool for calculating the force field. This motivates them to explain the AB effect without using the vector potential, which inevitably leads to some sort of non-locality. This frustrating situation is shortly summarized by the statement of Aharonov et al. that the AB effect may be due to a local gauge potential or due to non-local gauge-invariant fields. In the present paper, we shall give several convincing arguments, which support the viewpoint that the vector potential is not just a convenient mathematical tool with little physical entity. Despite its gauge arbitrariness, the vector potential certainly contains a gauge-invariant piece, which solely explains the observed AB phase shift. Importantly, this component has a property such that it is basically unique and cannot be eliminated by any regular gauge transformations. To make the discussion complete, we also discuss the role of remaining gauge arbitrariness still contained in the entire vector potential.
↳ quant-phhep-phnucl-thphysics.ed-phSymmetry(2025)·0 citations
11
Squeezing effect on three-dimensional Hanbury Brown-Twiss radii
Yong Zhang🇨🇳 · Peng Ru🇨🇳
This paper examines the impacts of the squeezing effect caused by the particle's in-medium mass modification on the three-dimensional Hanbury Brown-Twiss (HBT) radii. An analysis is conducted on how the squeezing effect impacts the three-dimensional HBT radii of $ϕϕ$ , $D^{0}$ $D^{0}$ , and $K^{+}$ $K^{+}$ . The squeezing effect suppresses the impacts of transverse flow on the transverse source distribution and broadens the space-time rapidity distribution of the particle-emitting source, leading to an increase in the HBT radii, notably in out and longitudinal direction. This phenomenon becomes more significant for higher transverse pair momentum, resulting in a non-monotonic decrease in the HBT radii with increasing transverse pair momentum. The impact of the squeezing effect on the HBT radii is more pronounced for $D^{0}$ $D^{0}$ than for $ϕϕ$ . Furthermore, this effect is also more significant for $ϕ$ $ϕ$ than for $K^{+}$ $K^{+}$ . The findings presented in this paper could offer fresh perspectives on investigating the squeezing effect.
↳ hep-phnucl-thCPC(2025)·0 citations
12
Towards a Global Search for New Physics with Isotope Shifts
Elina Fuchs🇩🇪 · Fiona Kirk🇩🇪 · Agnese Mariotti🇩🇪 · Jan Richter🇩🇪 · Matteo Robbiati🇮🇹
Isotope shifts have emerged as a sensitive probe of new bosons that couple to electrons and neutrons, and of nuclear structure. The recent Hz- or even sub-Hz-level isotope shift measurements across different elements call for a global assessment of all available data. In this work, we present the fit framework kifit that for the first time enables a combined analysis of isotope shift data from several elements, taking into account correlations. We provide a thorough comparison of analytical methods and the fit to analyse linear and nonlinear King plots and quantify their uncertainties. Finally, we provide recommendations for future measurements that could enhance the sensitivity to new physics and offer new insights into nuclear structure.
↳ physics.atom-phhep-phnucl-exnucl-thPRA(2025)·2 citations
13
Tracing the Evolution of Nuclear Excitation at the Electron-Ion Collider
Niseem Magdy🇺🇸
We investigate the evolution of nuclear excitation in electron-nucleus (e+A) collisions at the upcoming Electron-Ion Collider (EIC) using the BeAGLE event generator. Leveraging the EIC's unique collider kinematics, we demonstrate the remarkable capability to separate distinct nuclear reaction stages, hard scattering, intranuclear cascade, and nuclear de-excitation, in the laboratory frame. Our systematic analysis reveals that event-by-event fluctuations in the mean transverse momentum (k) are highly sensitive to the intranuclear cascade formation time and nuclear geometry, while minimally affected by variations in electron beam energy. These findings establish k as a robust observable for constraining nuclear excitation mechanisms, providing critical benchmarks for future EIC experiments and guiding theoretical advancements in nuclear transport modeling.
↳ hep-phnucl-exnucl-thPRC(2026)·1 citation
14
Level order of quark systems: The puzzle of the Roper resonance, and related questions
Jean-Marc Richard🇫🇷
The problem of ordering of radial vs.\ orbital excitations is reviewed. It is shown that the current quark models cannot explain the location of the Roper resonance which is slightly lower than the lowest negative-parity excitations. We also study some related spectral problems, such as the dependence of the energies on the quark masses, and the possibility of bound states in simple chromelectric models.
↳ hep-phnucl-thActa Phys.Polon.B(2026)·1 citation
15
Model Comparisons of Transverse Energy and Charged-Particle Multiplicity in A+A Collisions at Midrapidity from $s_{N N}$ $=$ 7.7 to 200~GeV
Niseem Magdy🇺🇸 · Antonio Silva🇺🇸 · Christal Martin🇺🇸 · Josie Hakanson🇺🇸 · Olivia Bartoshesky🇺🇸 · Aidan Hill🇺🇸 · Christine Nattrass🇺🇸
We present a comprehensive comparison of PHENIX measurements of transverse energy production ( $d E_{T} / d η$ ) and charged-particle multiplicity ( $d N / d η$ ) at midrapidity to simulations from PYTHIA-8, AMPT, HIJING, and SMASH. These comparisons span both small systems (d+Au, $^{3}$ He+Au) and large systems (Cu+Cu, Cu+Au, Au+Au, and U+U) at $s_{N N}$ $\sim$ 200~GeV and Au+Au over a range of beam energies $s_{N N} = 7.7$ --200~GeV. Using the Rivet framework, we assess the performance of these models. While general trends are captured, significant deviations persist, particularly in low-energy and peripheral collisions, underscoring the need for improved modeling of baryon stopping and energy deposition mechanisms.
↳ nucl-exhep-phnucl-thJ.Phys.G(2025)·0 citations

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first authorsco-authorsvia INSPIRE