Nuclear Theory·nucl-th

Tuesday·January 28, 2025

19 papers—13 primary·6 cross-listed

01
Signature of the $α$ -clustering structure of Light Nuclei in Relativistic Nuclear Collisions
Zhiyong Lu🇨🇳 · Mingrui Zhao🇨🇳 · Emil Gorm Dahlbæk Nielsen🇩🇰 · Xiaomei Li🇨🇳 · You Zhou🇩🇰
The "imaging-by-smashing" technique has been developed recently in relativistic nuclear collisions. By smashing heavy nuclei at RHIC and the LHC and analyzing the anisotropic expansion (flow) of the final state produced particles, unique information on the structure of the collided nuclei has been obtained. Existing efforts primarily focus on the colliding mode of heavy nuclei collisions. In contrast, nuclear structure studies with collisions of light nuclei and the fixed target mode, despite their significant impact and broad interest, have not been thoroughly explored. In this Letter, we investigate the $α$ -clustering signature of $^{20}$ Ne and $^{16}$ O in the fixed-target $^{208}$ Pb-- $^{20}$ Ne and $^{208}$ Pb-- $^{16}$ O collisions at $s_{_{NN}}$ = 68.5 GeV, using the parton transport model AMPT. The results of two- and four-particle cumulants of anisotropic flow demonstrate a robust $α$ -clustering signature that persists regardless of the complex dynamic evolution of the created systems. This study highlights the significant impact of the LHCb SMOG (SMOG2) project in discovering the $α$ -clustering signature of light nuclei at relativistic energies.
nucl-thnucl-exPLB(2025)·12 citations
02
Effects of sub-nucleonic fluctuations on the longitudinal structure of heavy-ion collisions
Oscar Garcia-Montero🇩🇪 · Sören Schlichting🇩🇪 · Jie Zhu🇩🇪
Sub-nuclear fluctuations in the initial state of heavy-ion collisions impact not only transverse long-range correlations of small systems, but also the creation of longitudinal structures, seen in particle detectors as longitudinal decorrelation observables. In this work, we study the emergence of long-range rapidity correlations in nuclear collisions based on the 3D resolved McDIPPER initial state model, and for the first time, connect it to experimental observables using the 3+1D viscous hydrodynamics framework CLVisc. We include different sources of fluctuations at the nucleon and subnucleon level and study the effects of these additional fluctuation sources on the longitudinal structure of relevant observables, such as the flow decorrelations and directed flow.
nucl-thhep-phPRD(2025)·12 citations
03
The 3- $α$ and 4- $α$ particle systems within short-range Effective Field Theory
E. Filandri · M. Viviani · L. Girlanda · A. Kievsky · L.E. Marcucci
$^{12} C$ and $^{16} O$ nuclei represent essential elements for life on Earth. The study of their formation plays a key role in understanding heavy element nucleosynthesis and stellar evolution. In this paper we present the study of $^{12} C$ and $^{16} O$ nuclei as systems composed of $α$ -particle clusters using the short-range effective field theory approach. The fundamental and excited states of the studied nuclei are calculated within an ab-initio approach, using the Hyperspherical Harmonics method. Thanks to the two-body potential and fine-tuning of the three-body force, we have found the $^{12} C$ system nicely reproduced by theory. However, for the $^{16} O$ case, it is necessary to include a 4-body force in order to achieve agreement with the experimental data.
nucl-thPRC(2025)·0 citations
04
Observing short-range correlations in nuclei through $ρ^{0}$ photo-production
Phoebe Sharp🇺🇸 · Axel Schmidt🇺🇸
Short-range correlations (SRCs) are a universal feature of nuclear structure. A wide range of measurements, primarily using electron scattering, have revealed SRC properties, such as their abundance in different nuclei, as well as the strong preference for proton-neutron pairing over proton-proton or neutron-neutron pairing. Despite the inherent complexity of many-body systems, a number of the salient features of electron scattering measurements are described by a simple, factorized theory called Generalized Contact Formalism. A key element of this theory, the factorization of the interaction with a hard probe, has yet to be tested. An experiment conducted at Jefferson Lab in 2021 collected data from scattering a tagged photon beam, with an energy up to 10 GeV, from several nuclear targets, measuring final state particles in the large-acceptance GlueX spectrometer. In this paper, we propose a test of probe factorization by measuring cross section ratios sensitive to proton-proton pair prevalence and relative SRC abundances in $^{4}$ He and $^{12}$ C. We present GCF predictions of the observables and make projections of the expected precision the experiment can achieve.
nucl-thnucl-exEPJA(2025)·2 citations
05
A hitchhiker's guide to nuclear polarization in muonic atoms
Mikhail Gorchtein🇩🇪
I consider the so-called nuclear polarization correction to the 1S-levels in light to intermediate muonic atoms. An easy to use recipe to compute it is given. The calculation includes the effect of the nucleon polarization, i.e. the contribution from inelastic states in the hadronic range, and Coulomb corrections beyond the leading logarithm approximation to both nuclear and nucleon polarization. I provide numerical estimates for $4 \leq Z \leq 41$ , compare to the estimates in the literature and discuss the need for future improvements.
nucl-thnucl-exphysics.atom-phPRC(2026)·12 citations
06
Shear Viscosity of Collider-Produced QCD Matter II: Comparing a Multi-Component Chapman-Enskog Framework with AMPT in Full Equilibrium
Noah M. MacKay🇩🇪
Transport properties of the quark-gluon plasma are instrumental to testing perturbative quantum chromodynamics and understanding the extreme conditions of relativistic heavy-ion collisions. This study presents an analytical investigation of the shear viscosity $η$ and the shear viscosity-to-entropy density ratio $η / s$ of the QGP using a novel multi-component Chapman-Enskog framework assuming full thermalization. The approach incorporates species-specific contributions from gluons and (anti-)quarks into the plasma shear viscosity, temperature-dependent running parameters for the Debye mass and strong coupling, and a time-dependent cooling model. Our findings show that both $η$ and $η / s$ are enhanced by the inclusion of (anti-)quarks with gluons, and the parameters decrease over time due to the cooling and expansion of the QGP. These results align with perturbative QCD predictions, offering a more optimistic representation of QGP transport properties under dynamic conditions. This multi-component framework is compared with a multi-phase transport model that treats the QGP as a gluon gas with (anti-)quark augmentation.
nucl-th0 citations
07
Investigating the pion emission source in pp collisions using the AMPT model with sub-nucleon structure
Dong-Fang Wang🇨🇳 · Mei-Yi Chen🇨🇳 · Yu-Gang Ma🇨🇳 · Qi-Ye Shou🇨🇳 · Song Zhang🇨🇳 · Liang Zheng🇨🇳
The measurement of momentum correlations of identical pions serves as a fundamental tool for probing the space-time properties of the particle emitting source created in high-energy collisions. Recent experimental results have shown that, in pp collisions, the size of the one-dimensional primordial source depends on the transverse mass (\mt) of hadron pairs, following a common scaling behavior, similar to that observed in Pb--Pb collisions. In this work, a systematic study of the \pipi source function and correlation function is performed using the multiphase transport model (AMPT) to understand the properties of the emitting source created in high multiplicity pp collisions at $s = 13$ TeV. The \mt scaling behavior and pion emission source radii measured by ALICE experiment can be well described the model with sub-nucleon structure. These studies shed new light on the understanding of the effective size of the \pipi emission source and on studying the intensity interferometry in small systems with a transport model.
nucl-thnucl-exNucl.Sci.Tech.(2025)·7 citations
08
Towards constraining QCD phase transitions in neutron star interiors: Bayesian Inference with TOV linear response analysis
Ronghao Li🇨🇳 · Sophia Han🇨🇳 · Zidu Lin🇺🇸 · Lingxiao Wang🇯🇵 · Kai Zhou🇨🇳 · Shuzhe Shi🇨🇳
The potential hadron-to-quark phase transition in neutron stars has not been fully understood as the property of cold, dense, and strongly interacting matter cannot be theoretically described by the first-principle perturbative calculations, nor have they been systematically measured through terrestrial low-to-intermediate energy heavy-ion experiments. Given the Tolman--Oppenheimer--Volkoff (TOV) equations, the equation of state (EoS) of the neutron star (NS) matter can be constrained by the observations of NS mass, radius, and tidal deformability. However, large observational uncertainties and the limited number of observations currently make it challenging to strictly reconstruct the EoS, especially to identify interesting features such as a strong first-order phase transition. In this work, we study the dependency of reconstruction quality of the phase transition on the number of NS observations of mass and radius as well as their uncertainty, based on a fiducial EoS. We conquer this challenging problem by constructing a neural network, which allows one to parametrize the EoS with minimum model-dependency, and by devising an algorithm of parameter optimization based on the analytical linear response analysis of the TOV equations. This work may pave the way for the understanding of the phase transition features in NSs using future $x$ -ray and gravitational wave measurements.
nucl-thastro-ph.HEhep-thPRD(2025)·18 citations
09
Core screening effect in knockout reactions
Shichang Li · Junchen Pei · Danyang Pang
The systematic quenching of spectroscopic factors in terms of separation energy asymmetry in single-nucleon knockout reactions remains a puzzle. We propose a core screening effect to consider the hindrance when strongly bound nucleons in the projectile nucleus are removed by the heavy-ion target. The core screening effect is simulated as a density dependent suppression of single-particle wave functions inside the core of projectile. Our study shows that the parameterized core screening effect can significantly reduce the isospin dependence of quenching factors, offering insights into nuclear reaction mechanisms.
nucl-th0 citations
10
The correlation between the $α$ -cluster separation and the neutron S-factor in $^{12}$ Be
Zhilian Cai · Qing Zhao · Zaihong Yang · Masaaki Kimura · Bo Zhou · Seung-heon Shin
The reduced width amplitudes (RWA) and the spectroscopic factor (S-factor) of $α$ -cluster and valence neutron in $^{12}$ Be are calculated by the generator coordinates method (GCM) with the cluster model. By fixing the distance between the $α$ -clusters' generated coordinates, we make a theoretical experiment to analyze the relationship between the $α$ -clustering separation and the orbital occupation of the valence neutron in $^{12}$ Be. The analysis of the results shows that the percentage of the $σ$ orbital occupation in $^{12}$ Be is positively related to the clustering separation.
nucl-thPRC(2025)·0 citations
11
Cluster configurations in Li isotopes in the variation of multi-bases of the antisymmetrized molecular dynamics
Takayuki Myo · Mengjiao Lyu · Qing Zhao · Masahiro Isaka · Niu Wan · Hiroki Takemoto · Hisashi Horiuchi · Akinobu Dote
We investigate the cluster configurations in Li isotopes, which are described in the optimization of the multi-Slater determinants of the antisymmetrized molecular dynamics. Each Slater determinant in the superposition is determined simultaneously in the variation of the total energy. The configurations of the excited states are obtained by imposing the orthogonal condition to the ground-state configurations. In Li isotopes, various cluster configurations are confirmed and are related to the thresholds of the corresponding cluster emissions. For $^{5}$ Li, we predict the $^{3}$ He+ $d$ clustering in the excited state as well as the mirror state of $^{5}$ He with $^{3}$ H+ $d$ . For $^{6 - 9}$ Li, various combinations of the clusters are obtained in the ground and excited states, and the superposition of these basis states reproduces the observed energy spectra. For $^{9}$ Li, we predict the linear-chain states consisting of various cluster configurations at 10--13 MeV of the excitation energy.
nucl-thnucl-exPTEP(2025)·10 citations
12
Imaging nuclei by smashing them at high energies: how are their shapes revealed after destruction?
Jiangyong Jia🇺🇸
High-energy nuclear collisions have recently emerged as a promising ``imaging-by-smashing'' approach that may reveal the intrinsic shapes of atomic nuclei. Here, I outline a conceptual framework for this technique, explaining how nuclear shapes are encoded during quark-gluon plasma formation and evolution, and how they can be decoded from final-state particle distributions. I highlight the method's potential to advance our understanding of both nuclear structure and quark-gluon plasma physics.
nucl-thhep-phnucl-exphysics.atm-clus+1Rept.Prog.Phys.(2025)·14 citations
13
Correlations between nuclear incompressibility, liquid-gas critical point, and quarkyonic transition
Artemiy Lysenko🇺🇦 · Mark I. Gorenstein🇺🇦 · Tripp Moss🇺🇸 · Roman Poberezhniuk🇺🇦 · Volodymyr Vovchenko🇺🇸
We systematically probe different parametrizations of the attractive nuclear force based on real gas models to construct the nuclear matter equation of state. In each of the cases, the repulsion between nucleons is treated in the framework of excluded volume, and interaction parameters are fitted to the empirical properties of the nuclear ground state. We calculate the critical temperature $T_{c}$ and critical particle number density $n_{c}$ , and find that they are strongly correlated. Both are also correlated with the incompressibility $K_{0}$ in the nuclear ground state. We also include a quarkyonic matter phase in the quasiparticle description and investigate the relationships among $K_{0}$ , transition density to the quarkyonic phase, $n_{t r}$ , and corresponding peak in the speed of sound, $v_{s, max}^{2}$ . At each density, the quark fraction is found by minimizing the energy density. We find that both $n_{t r}$ and $v_{s, max}^{2}$ are negatively correlated with $K_{0}$ , $n_{c}$ , and $T_{c}$ .
nucl-thPRC(2025)·3 citations
14
Comparing strange and non-strange quark stars within resummed QCD at NLO
Tulio E. Restrepo🇺🇸 · Jean-Loïc Kneur🇫🇷 · Constança Providência🇵🇹 · Marcus Benghi Pinto🇧🇷
We employ the renormalization group optimized perturbation theory (RGOPT) resummation method to evaluate the equation of state (EoS) for strange ( $N_{f} = 2 + 1$ ) and non-strange ( $N_{f} = 2$ ) cold quark matter at NLO. This allows us to obtain the mass-radius relation for pure quark stars and compare the results with the predictions from perturbative QCD (pQCD) at NNLO. Choosing the renormalization scale to generate maximum star masses of order $M = 2 - 2.6 M_{⊙}$ , we show that the RGOPT can produce mass-radius curves compatible with the masses and radii of some recently observed pulsars, regardless of their strangeness content. The scale values required to produce the desired maximum masses are higher in the strange scenario since the EoS is softer in this case. The possible reasons for such behavior are discussed. Our results also show that, as expected, the RGOPT predictions for the relevant observables are less sensitive to scale variations than those furnished by pQCD.
↳ hep-phastro-ph.HEnucl-thPRD(2025)·7 citations
15
Roles of $Δ (1232)$ , $N^{*} (1520)$ , and $N^{*} (1650)$ resonances in $γ p \to π^{0} π^{0} p$ reaction within an effective Lagrangian approach
Meng-Yuan Dai🇨🇳 · Si-Wei Liu🇨🇳 · Cheng Chen🇨🇳 · De-Min Li🇨🇳 · En Wang🇨🇳 · Ju-Jun Xie🇨🇳
Roles of the $Δ (1232)$ , $N^{*} (1520)$ , and $N^{*} (1650)$ resonances in the $γ p \to π^{0} π^{0} p$ reaction near threshold is investigated within an effective Lagrangian approach. We have calculated the differential cross sections of the $γ p \to π^{0} π^{0} p$ reaction by including the contributions from the $Δ (1232)$ , $N^{*} (1520)$ , and $N^{*} (1650)$ intermediate states decaying into $π^{0} p$ via the $s$ -channel nucleon pole and $t$ -channel $ρ$ exchange, and found that the current experimental measurements can be well reproduced. The production of $Δ (1232)$ is mainly from the mechanism of the $s$ -channel nucleon pole, while the $N^{*} (1520)$ and $N^{*} (1650)$ are produced from the mechanism of the $t$ -channel $ρ$ exchange. It is expected that more experimental data on the $γ p \to π^{0} π^{0} p$ reaction can be used to explore the properties of the low-lying excited baryon states and also the scalar $f_{0} (500)$ and $f_{0} (980)$ mesons.
↳ hep-phnucl-thCPC(2025)·6 citations
16
Explainable autoencoder for neutron star dense matter parameter estimation
Francesco Di Clemente · Matteo Scialpi · Michał Bejger
We present a physics-informed autoencoder designed to encode the equation of state of neutron stars into an interpretable latent space. In particular the input will be encoded in the mass, radius, and tidal deformability values of a neutron star. Unlike traditional black-box models, our approach incorporates additional loss functions to enforce explainability in the encoded representations. This method enhances the transparency of machine learning models in physics, providing a robust proof-of-concept tool to study compact stars data. Our results demonstrate that the proposed autoencoder not only accurately estimates the EoS parameters and central density/pressure but also offers insights into the physical connection between equation of state and observable physical quantities. This framework conceptualizes the physical differential equations themselves as the ``encoders", allowing interpretability of the latent space.
↳ physics.comp-phastro-ph.HEastro-ph.IMnucl-thMach.Learn.Sci.Tech.(2025)·7 citations
17
Microscopic composite systems bound by strong gravity in extra dimensions as candidates for dark matter
V. V. Flambaum🇦🇺
In the Arkani-Hamed-Dimopoulos-Dvali (ADD) model with n extra compactified dimensions, the gravitational potential scales as 1/r^{n+1} and becomes significantly stronger at short distances. We investigate the possibility of forming small-sized composite systems of Standard Model particles bound by this potential. Such bound states, composed of quarks, neutrinos, axions, or other particles, exhibit a small cross-section-to-mass ratio, making them viable candidates for dark matter.
↳ hep-phastro-ph.COnucl-thphysics.atom-phPRD(2025)·2 citations
18
Three flavor QCD phase transition with Möbius domain wall fermions
Yu Zhang🇩🇪 · Yasumichi Aoki🇯🇵 · Shoji Hashimoto🇯🇵 · Issaku Kanamori🇯🇵 · Takashi Kaneko🇯🇵 · Yoshifumi Nakamura🇯🇵
We present an updated study of the $N_{f} = 3$ QCD phase transition using Möbius domain wall fermions. Simulations were performed on $N_{t} = 12$ lattices with aspect ratios ranging from 2 to 4 for various quark masses, at a lattice spacing of $a = 0.1361 (20)$ fm, corresponding to a temperature of 121(2) MeV. To clarify the nature of the phase transition, a large-volume lattice, $4 8^{3} \times 12 \times 16$ , was added to analyze the volume dependence of disconnected chiral susceptibility. By examining the chiral condensate, disconnected chiral susceptibility, and Binder cumulant, and incorporating results from $2 4^{3} \times 12 \times 16$ and $3 6^{3} \times 12 \times 16$ lattices reported in earlier studies, we observe that the transition is consistent with a crossover at a quark mass of approximately $m_{f}^{MS} (2 GeV) \sim 4$ MeV at this temperature. Furthermore, we discuss the effects of residual chiral symmetry breaking on the chiral condensate and disconnected chiral susceptibility for different sizes in the 5th direction.
↳ hep-lathep-thnucl-thPoS(2025)·10 citations
19
Aspects of the dilute Glasma
Markus Leuthner🇦🇹
The Glasma is a semiclassical nonequilibrium state describing the earliest stage in relativistic heavy-ion collisions predicted by the Color Glass Condensate effective theory. It is characterized by strong color fields, which are sourced by color currents pertaining to hard partons in the colliding nuclei. We introduce the (3+1)D dilute Glasma framework, which incorporates the longitudinal and transverse structure of colliding particles and describes the rapidity-dependence of observables like the energy-momentum tensor. This is in stark contrast to the canonical picture of boost-invariance, where nuclei are infinitesimally thin in longitudinal direction, and the rapidity-dependence of observables is lost. We discuss the derivation of the (3+1)D dilute Glasma field-strength tensor, which relies on linearizing the Yang-Mills equations in the dilute approximation, i.e., assuming weak sources. The dilute Glasma energy-momentum tensor can efficiently be evaluated numerically on a lattice. Employing a generalized 3D McLerran-Venugopalan model, we discuss numerical results for the collisions of heavy ions at energies corresponding to experiments at RHIC and the LHC. We discover longitudinal flow that differs significantly from Bjorken flow and argue that this is a consequence of taking into account the longitudinal extension of nuclei. Furthermore, we find limiting fragmentation as a universal feature of the dilute Glasma analytically and numerically. Finally, we study the applicability of the dilute Glasma to proton-proton collisions and show the necessary modifications to reproduce experimental multiplicity distributions.
↳ hep-phnucl-th4 citations

Affiliations

first authorsco-authorsvia INSPIRE