Nuclear Theory·nucl-th

Tuesday·June 4, 2024

14 papers—4 primary·10 cross-listed

01
Methodology for Analyzing Proton Multiplicity Fluctuations with Azimuthal Partitions in Heavy-Ion Collisions
Dylan Neff🇺🇸 · Zhongling Ji🇺🇸 · Roli Esha🇺🇸 · Gang Wang🇺🇸 · Huan Huang🇺🇸
A primary objective in high-energy heavy-ion collisions is to investigate the phase transition between confined and deconfined color matter. Complementary to the cumulants of conserved charges integrated over the full azimuth, we introduce a novel experimental approach to explore particle fluctuations in azimuthal partitions, which are potentially sensitive to the first-order phase transition in heavy-ion collisions. We evaluate proton multiplicity ( $N_{w}$ ) fluctuations in azimuthal partitions of width $w$ to quantitatively estimate the clustering tendency among these protons. The $Δ σ^{2}$ observable is defined as the normalized difference between the variance of the $N_{w}$ distribution and the binomial baseline. We demonstrate the feasibility and characteristics of this observable through simulations using the AMPT and MUSIC+FIST models. We also use a Gaussian correlation model to illustrate that the dependence of $Δ σ^{2}$ on $w$ can be parameterized to accurately extract the strength and the range of the input interaction among protons.
nucl-thhep-phnucl-exPRC(2024)·1 citation
02
Finite-temperature equations of state of compact stars with hyperons: three-dimensional tables
Stefanos Tsiopelas🇵🇱 · Armen Sedrakian🇵🇱 · Micaela Oertel🇫🇷
We construct tables of finite temperature equation of state (EoS) of hypernuclear matter in the range of densities, temperatures, and electron fractions that are needed for numerical simulations of supernovas, proto-neutron stars, and binary neutron star mergers and cast them in the format of {\sc CompOSE} database. The tables are extracted from a model that is based on covariant density functional (CDF) theory that includes the full $J^{P} = 1/ 2^{+}$ baryon octet in a manner that is consistent with the current astrophysical and nuclear constraints. We employ a parameterization with three different values of the slope of the symmetry energy $L_{sym} = 30$ , 50 and 70 MeV and fixed skewness $Q_{sat} = 400$ MeV for above saturation matter. A model for the EoS of inhomogeneous matter is matched at sub-saturation density to the high-density hypernuclear EoS. We discuss the generic features of the resulting EoS and the composition of matter as a function of density, temperature, and electron fraction. The nuclear characteristics and strangeness fraction of these models are compared to the alternatives from the literature. The integral properties of static and rapidly rotating compact stars in the limit of zero temperature are discussed and confronted with the multimessenger astrophysical constraints.
nucl-thastro-ph.HEastro-ph.SREPJA(2024)·26 citations
03
Study of the alpha-particle monopole transition form factor
M. Viviani · A. Kievsky · L.E. Marcucci · L. Girlanda
The 4He monopole form factor is studied by computing the transition matrix element of the electromagnetic charge operator between the 4He ground-state and the p+3H and n+3He scattering states. The nuclear wave functions are calculated using the hyperspherical harmonic method, by starting from Hamiltonians including two- and three-body forces derived in chiral effective field theory. The electromagnetic charge operator retains, beyond the leading order (impulse approximation) term, also higher order contributions, as relativistic corrections and meson-exchange currents. The results for the monopole form factor are in fairly agreement with recent MAMI data. Comparison with other theoretical calculations are also provided.
nucl-thFew Body Syst.(2024)·6 citations
04
Reexamination of antinucleon-nucleon interactions in covariant chiral effective field theory
Yang Xiao🇨🇳 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳
Motivated by the recent progress in developing high-precision relativistic chiral nucleon-nucleon interactions, we study the antinucleon-nucleon interaction in a hybrid approach where the real part of the potential is constructed in the leading-order covariant chiral effective field theory, and the imaginary part is described following the procedure adopted in the heavy baryon chiral effective field theory. The phase shifts and inelasticities with $J \leq 1$ are obtained and compared to those calculated in the next-to-leading order heavy baryon chiral effective field theory. For most partial waves, the descriptions of phase shifts and inelasticities in the hybrid approach are comparable to those in the next-to-leading order heavy baryon chiral effective field theory, confirming the relatively faster convergence of the relativistic approach observed in the nucleon-nucleon sector. In addition, we search for bound states/resonances near the $N ˉ N$ threshold and find several structures that can be associated with those states recently observed by the BESIII Collaboration.
nucl-thhep-phPRC(2024)·8 citations
05
High-accuracy Nuclear Spin Dependent Parity Violating Amplitudes in $^{133}$ Cs
A. Chakraborty · B. K. Sahoo
Relativistic coupled-cluster (RCC) theory at the singles and doubles approximation has been implemented to estimate nuclear spin dependent (NSD) parity violating (PV) electric dipole (E1) transition amplitudes ( $E 1_{P V}^{N S D}$ ) among hyperfine levels of the $6 s^{2} S_{1/2} \to 7 s^{2} S_{1/2}$ transition in $^{133}$ Cs. To validate our calculations, we reproduce the Dirac-Hartree-Fock values and results from the combined coupled-Dirac-Hartree-Fock and random phase approximation (CPDF-RPA) method reported earlier. Contributions from the double-core-polarization (DCP) effects at the CPDF-RPA method were found to be between 3-12\% among different hyperfine levels. We derived a generalized expression for $E 1_{P V}^{N S D}$ , which helped incorporate both the NSD PV Hamiltonian and E1 operator simultaneously in the perturbative approach to account for the DCP contributions. The RCC method subsumes the CPDF-RPA and DCP effects in addition to contributions from the Brückner pair-correlations and normalization of the wave functions, and correlations among them. To improve accuracy of the $E 1_{P V}^{N S D}$ amplitudes further, we replace the {\it ab initio} values of the E1 matrix elements and energies by their experimental values via a sum-over-states approach.
↳ physics.atom-phnucl-thPRA(2024)·3 citations
06
Inhomogenuous instabilities at large chemical potential in a rainbow-ladder QCD model
Theo F. Motta🇩🇪 · Julian Bernhardt🇩🇪 · Michael Buballa🇩🇪 · Christian S. Fischer🇩🇪
In this work we continue our efforts to study the existence of a phase with an inhomogeneous, i.e., spatially varying, chiral condensate in QCD. To this end we employ a previously established method of stability analysis of the two-particle irreducible effective action in a truncation that corresponds to a rainbow-ladder approximation of the quark-gluon interaction of QCD. If the analysis is restricted to homogeneous phases, the phase diagram features a first-order chiral transition in the lower-temperature regime. Performing the stability analysis along the lower-chemical-potential border of the corresponding spinodal region, we find that below a certain temperature the homogeneous chirally symmetric solution is unstable against inhomogeneous condensation. We argue that this instability may persist to chemical potentials above the homogeneous first-order phase boundary, in which case it signals the existence of an inhomogeneous ground state. Our methodology is also applicable for more sophisticated truncations of the QCD effective action.
↳ hep-phnucl-thPRD(2024)·16 citations
07
Generalized Fluid Models of the Braginskii Type. Part 2. The Boltzmann Operator
P. Hunana
In our previous paper (Hunana et al. 2022) we have employed the Landau collisional operator together with the moment method of Grad and considered various generalizations of the Braginskii model, such as a multi-fluid formulation of the 21- and 22-moment models valid for general masses and temperatures, where all of the considered moments are described by their evolution equations (with fully non-linear left-hand-sides). Here we consider the same models, however, we employ the Boltzmann operator and calculate the collisional contributions via expressing them through the Chapman-Cowling collisional integrals. These ``integrals'' just represent a useful mathematical technique/notation introduced roughly 100 years ago, which (in the usual semi-linear approximation) allows one to postpone specifying the particular collisional process and finish all of the calculations with the Boltzmann operator. We thus consider multi-fluid 21- and 22-moment models which are valid for a large class of elastic collisional processes describable by the Boltzmann operator. Reduction into the 13-moment approximation recovers the models of Schunk and Burgers. We only focus on the particular cases of hard spheres, Coulomb collisions, purely repulsive inverse power force $∣ K ∣/ r^{ν}$ and attractive force $- ∣ K ∣/ r^{ν}$ with repulsive rigid core (or potential $V (r) = δ (r) - ∣ c ∣/ r^{n}$ , so that the particles bounce from each other when they meet), but other cases can be found in the literature. In the Appendix, we introduce the Boltzmann operator in a way suitable for newcomers and we discuss a surprisingly simple recipe how to calculate the collisional contributions with analytic software.
↳ physics.plasm-phastro-ph.SRnucl-thAstrophys.J.Suppl.(2025)·1 citation
08
Compact dwarfs made of light-quark nuggets
Hao-Song You🇨🇳 · Hao Sun🇨🇳 · Hong-Bo Li🇨🇳 · Cheng-Jun Xia🇨🇳 · Ren-Xin Xu🇨🇳
Utilizing an equivparticle model with both linear confinement and leading-order perturbative interactions, we obtain systematically the properties of strangelets and nonstrange quark matter ( $u d$ QM) nuggets at various baryon ( $A$ ) and charge ( $Z$ ) numbers, where the detailed single-quark-energy levels are fixed by solving Dirac equations in mean-field approximation (MFA). We then examine the structures of compact dwarfs made of light strangelets or $u d$ QM nuggets forming body-centered cubic lattices in a uniform electron background. Despite the strangelets and $u d$ QM nuggets generally become more stable at larger $A$ , the compact dwarfs are still stable since the fusion reactions between those objects do not take place in the presence of a Coulomb barrier, which is similar to the cases of light nuclei in normal white dwarfs. If $u d$ QM dwarfs or strangelet dwarfs are covered with normal matter, their masses and radii become larger but do not exceed those of ordinary white dwarfs. Finally, we investigate the radial oscillation frequencies of $u d$ QM dwarfs and strangelet dwarfs, and find that their frequencies are typically higher than traditional white dwarfs. The stability of compact dwarfs are then analysised by examining radial oscillation frequencies of the fundamental mode, where compact dwarfs covered by normal matter are still stable.
↳ hep-phnucl-thPRD(2024)·0 citations
09
Role of particle diffusion in shaping the gravitational wave signal from neutron star inspirals
Elena M. Kantor🇷🇺 · Mikhail E. Gusakov🇷🇺 · Kirill Y. Kraav🇷🇺
It is commonly believed that the dissipative properties of superdense matter play a negligible role in modeling gravitational waveforms from neutron star inspirals. This study aims to investigate whether this presumption holds true for the often neglected dissipative process associated with particle diffusion in superconducting neutron stars. As we demonstrate, diffusion effects can significantly impact the phase of the gravitational wave from the inspiral, manifesting at a magnitude of a few tens of milliradians at large orbit separations, equivalent to orbital frequencies of a few hertz. We also find that dissipation resulting from particle diffusion might increase the neutron star's temperature to approximately $1 0^{7} K$ during the inspiral.
↳ astro-ph.HEastro-ph.SRgr-qcnucl-thPRD(2024)·1 citation
10
Quantum turbulence, superfluidity, non-Markovian dynamics, and wave function thermalization
A. Bulgac · M. Kafker · I. Abdurrahman · G. Wlazlowski
While quantum turbulence has been addressed both experimentally (predominantly for superfluid $^{4}$ He and $^{3}$ He) and theoretically, the dynamics of various ensembles of quantized vortices was followed in time only until the vortices decay into phonons. How this ``thermalization'' is achieved is still an unaddressed and thus an unelucidated question. The Unitary Fermi Gas (UFG) is a unique quantum system, which has no classical counterpart and of relevance to neutron stars, cold atoms, condensed matter and nuclear many-body systems. The non-Markovian evolution of an isolated UFG is put in evidence and its entire non-equilibrium evolution can be studied theoretically within a unified theoretical framework. The initial lattice of quantum vortices and anti-vortices evolves through a couple of vortex tangles and excitation of Kelvin waves, where vortices cross and reconnect, until very slowly thermalization sets in.
↳ cond-mat.quant-gasnucl-thPRResearch(2024)·8 citations
11
Understanding the nature of the $Δ (1600)$ resonance
Liam Hockley🇦🇺 · Curtis Abell🇦🇺 · Derek Leinweber🇦🇺 · Anthony Thomas🇦🇺
We present a coupled-channel analysis of the $J^{P} = 3/ 2^{+} Δ$ -baryon spectrum, based in the framework of Hamiltonian Effective Field Theory (HEFT). We construct a Hamiltonian which mixes quark model-like single-particle states and two-particle meson-baryon channels, and constrain this via experimentally measured $π N \to π N$ scattering observables. In the same vein as Lüscher's approach, we then connect this infinite-volume inspired Hamiltonian with finite-volume lattice QCD results. Drawing on lattice correlation-matrix eigenvectors identifying the $1 s$ and $2 s$ states in the finite-volume $Δ (3/ 2^{+})$ spectrum, and utilising the HEFT eigenvectors describing the composition of the energy eigenstates, we resolve the structure of these states and their relation to the $Δ (1600)$ resonance. We find the dominant contributions to this resonance come from strong rescattering in the $π N$ and $π Δ$ channels. This contrasts the long-held view of a dominant quark model-like core for the $Δ (1600)$ . Further discussion of other contemporary lattice results for the $Δ$ spectrum and $π N$ scattering states is also presented.
↳ hep-phhep-latnucl-thPRD(2025)·13 citations
12
Parton distribution functions and fragmentation functions of spin-1 hadrons
S. Kumano🇯🇵
Structure functions of the spin-1 deuteron will be investigated experimentally from the late 2020's at various facilities such as Thomas Jefferson National Accelerator Facility, Fermi National Accelerator Laboratory, nuclotron-based ion collider facility, and electron-ion colliders. We expect that a new high-energy spin-physics field could be created by these projects. In this paper, the current theoretical status is explained for the structure functions of spin-1 hadrons, especially on parton distribution functions, transverse-momentum dependent parton distributions, and fragmentation functions. Related multiparton distribution functions are also shown.
↳ hep-phhep-exhep-latnucl-ex+1EPJA(2024)·12 citations
13
Low energy alpha-nucleus optical potential studied via (a,n) cross section measurements on Te isotopes
Zs. Mátyus · Gy. Gyürky · P. Mohr · A. Angyal · Z. Halász · G.G. Kiss · Á Tóth · T. Szücs · Zs. Fülöp
In several processes of stellar nucleosynthesis, like the astrophysical gamma-process, nuclear reactions involving alpha particles play an important role. The description of these reactions necessitates the knowledge of the alpha-nucleus optical model potential (AOMP) which is highly ambiguous at low, astrophysical energies. This ambiguity introduces a substantial uncertainty in the stellar models for predicting elemental and isotopic abundances. The experimental study of the AOMP is thus necessary which can be implemented by measuring the cross section of alpha-induced nuclear reactions. At low energies, (a,n) reactions are suitable for such a purpose. Therefore, in the present work, the (a,n) cross sections of four Te isotopes have been measured, mostly for the first time, and compared with theoretical predictions. The (a,n) cross sections of 120,122,124,130Te have been measured in the energy range between about 10 and 17 MeV using the activation method. The detection of the gamma radiation following the decay of the radioactive reaction products were used to determine the cross sections. The measured cross sections are compared with statistical model calculations obtained from the widely used TALYS nuclear reaction simulation code. Predictions using various available AOMPs are investigated. It is found that the recently developed Atomki-V2 AOMP provides the best description for all studied reactions and this potential also reproduces well the total reaction cross sections from elastic scattering experiments, when they are available in literature. We recommend therefore to use the astrophysical reaction rates based on this potential for nucleosynthesis models of heavy elements.
↳ nucl-exastro-ph.SRnucl-thPRC(2024)·2 citations
14
On the role of $J / ψ$ production in electron-ion collisions
Zexuan Chu🇨🇳 · Jinhui Chen🇨🇳 · Xiang-Peng Wang🇩🇪 · Hongxi Xing🇨🇳
Within the framework of non-relativistic QCD (NRQCD) effective field theory, we study the leptoproduction of $J / ψ$ at next-to-leading order in perturbative QCD for both unpolarized and polarized electron-ion collisions. We demonstrate that the $J / ψ$ -tagged deep inelastic scattering in the future Electron-Ion Collider can be served as a golden channel for the reasons including constraining NRQCD long distance matrix elements, probing the nuclear gluon distribution functions, as well as investigating the gluon helicity distribution inside a longitudinal polarized proton.
↳ hep-phnucl-thPRD(2025)·4 citations

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first authorsco-authorsvia INSPIRE