Nuclear Theory·nucl-th

Tuesday·December 6, 2022

12 papers—6 primary·6 cross-listed

01
A Kohn-Sham Scheme Based Neural Network for Nuclear Systems
Zu-Xing Yang · Xiao-Hua Fan · Zhi-Pan Li · Haozhao Liang
A Kohn-Sham scheme based multi-task neural network is elaborated for the supervised learning of nuclear shell evolution. The training set is composed of the single-particle wave functions and occupation probabilities of 320 nuclei, calculated by the Skyrme density functional theory. It is found that the deduced density distributions, momentum distributions, and charge radii are in good agreements with the benchmarking results for the untrained nuclei. In particular, accomplishing shell evolution leads to a remarkable improvement in the extrapolation of nuclear density. After a further charge-radius-based calibration, the network evolves a stronger predictive capability. This opens the possibility to infer correlations among observables by combining experimental data for nuclear complex systems.
nucl-thPLB(2023)·14 citations
02
Charge-dependent anisotropic flow in high-energy heavy-ion collisions from relativistic resistive magneto-hydrodynamic expansion
Kouki Nakamura🇯🇵 · Takahiro Miyoshi🇯🇵 · Chiho Nonaka🇯🇵 · Hiroyuki R. Takahashi🇯🇵
We have investigated the charge-dependent anisotropic flow in high-energy heavy-ion collisions, using relativistic resistive magneto-hydrodynamics (RRMHD). We consider the optical Glauber model as an initial model of the quark-gluon plasma (QGP) and the solution of the Maxwell equations with source term of the charged particles in two colliding nuclei as initial electromagnetic fields. The RRMHD simulation is performed with these initial conditions in Au-Au and Cu-Au collisions at $s_{NN} = 200$ GeV. We have calculated the charge-odd contribution to the directed flow $Δ v_{1}$ and elliptic flow $Δ v_{2}$ in both collisions based on electric charge distributions as a consequence of RRMHD. Our results show that the $Δ v_{1}$ and $Δ v_{2}$ are approximately proportional to the electrical conductivity ( $σ$ ) of the medium. In the $σ = 0.023 fm^{- 1}$ case, our result of $Δ v_{1}$ is consistent with STAR data in Au-Au collisions. Furthermore, in Cu-Au collisions, $Δ v_{1}$ has a non-zero value at $η = 0$ . We conclude that the charge-dependent anisotropic flow is a good probe to extract the electrical conductivity of the QGP medium in high-energy heavy-ion experiments.
nucl-thhep-phnucl-exPRC(2023)·17 citations
03
Progress in Nuclear Astrophysics: a multi-disciplinary field with still many open questions
S. Goriely · A. Choplin · W. Ryssens · I. Kullmann
Nuclear astrophysics is a multi-disciplinary field with a huge demand for nuclear data. Among its various fields, stellar evolution and nucleosynthesis are clearly the most closely related to nuclear physics. The need for nuclear data for astrophysics applications challenges experimental techniques as well as the robustness and predictive power of present nuclear models. Despite impressive progress for the last years, major problems and puzzles remain. In the present contribution, only a few nuclear astrophysics specific aspects are discussed. These concern some experimental progress related to the measurement of key reactions of relevance for the so-called s-and p-processes of nucleosynthesis, the theoretical effort in predicting nuclear properties of exotic neutron-rich nuclei of interest for the r-process nucleosynthesis, and the recent introduction of machine learning techniques in nuclear astrophysics applications.
nucl-thastro-ph.HEastro-ph.SRnucl-exJ.Phys.Conf.Ser.(2023)·1 citation
04
Influence of hyperon-hyperon interaction on the properties of neutron stars
R. M. Aguirre🇦🇷
The properties of neutron stars are studied in a composite model of the strong interaction. In the regime of low to medium baryonic densities a covariant hadronic model is adopted which includes an exclusive channel for the hyperon-hyperon interaction mediated by hidden strangeness mesons, which in turn couple to other mesons through polynomial vertices. The new coupling constants are subject to phenomenological constraints. The presence of free quarks in the core of the star is considered by using the Nambu-Jona Lasinio model supplemented with a vector interaction. The deconfinement process is described by a continuous coexistence of phases. Several structure parameters of neutron stars, such as mass-radius relation, moment of inertia, tidal deformability, and the propagation of nonradial f and g-modes within the relativistic Cowling approximation are studied. The predictions of the model are in good agreement with recent observational data, in particular the maximum inertial mass is greater than the observational lower limit of two solar masses.
nucl-thastro-ph.HEhep-phJ.Phys.G(2024)·2 citations
05
Complex eigenenergy of GDR for $^{16}$ O by the Jost function within RPA framework
K. Mizuyama · N. Nhu Le · T. V. Nhan Hao · N. Hoang Tung · T. Dieu Thuy
The Jost function method is extended within the framework of the RPA theory to find poles on the complex energy plane that exhibit complex RPA eigenenergies. Poles corresponding to the RPA excited states such as the giant resonance of $^{16}$ O electric dipole excitations were successfully found on the complex energy plane. Although the giant resonance has been known as a single resonance with large strength and width, it is found that, at least within the RPA framework, the $^{16}$ O electric dipole giant resonance is formed by multiple poles, each of which is an independent pole with different widths, origins, response properties to residual interactions, and components structures of the density fluctuation.
nucl-thPRC(2023)·4 citations
06
Metric anisotropies and nonequilibrium attractor for expanding plasma
Nisarg Vyas🇮🇳 · Sunil Jaiswal🇮🇳 · Amaresh Jaiswal🇮🇳
We consider the evolution of a system of chargeless and massless particles in an anisotropic space-time given by the Bianchi type I metric. Specializing to the axis-symmetric case, we derive the framework of anisotropic hydrodynamics from the Boltzmann equation in the relaxation-time approximation. We consider the case of the axis-symmetric Kasner metric and study the approach to the emergent attractor in near and far-off-equilibrium regimes. Further, by relaxing the Kasner conditions on metric coefficients, we study the effect of expansion geometries on the far-off-equilibrium attractor and discuss its implications in the context of relativistic heavy-ion collisions.
nucl-thhep-phhep-thPLB(2023)·6 citations
07
Equation of state and Taylor expansions at nonzero isospin chemical potential
Bastian B. Brandt🇩🇪 · Francesca Cuteri🇩🇪 · Gergely Endrödi🇩🇪
We compute the equation of state of isospin asymmetric QCD at zero and non-zero temperatures using direct simulations of lattice QCD with three dynamical flavors at physical quark masses. In addition to the pressure and the trace anomaly and their behavior towards the continuum limit, we will particularly discuss the extraction of the speed of sound. Furthermore, we discuss first steps towards the extension of the EoS to small non-zero baryon chemical potentials via Taylor expansion.
↳ hep-lathep-phnucl-thPoS(2023)·12 citations
08
Fusion Reactivities with Drift bi-Maxwellian Ion Velocity Distributions
Huasheng Xie · Muzhi Tan · Di Luo · Zhi Li · Bing Liu
The calculation of fusion reactivity involves a complex six-dimensional integral that takes into account the fusion cross-section and velocity distributions of two reactants. However, a more simplified one-dimensional integral form can be useful in certain cases, such as for studying fusion yield or diagnosing ion energy spectra. This simpler form has been derived in a few special cases, such as for a combination of two Maxwellian distributions, a beam-Maxwellian combination, and a beam-target combination, and can greatly reduce computational costs. In this study, it is shown that the reactivity for two drift bi-Maxwellian reactants with different drift velocities, temperatures, and anisotropies can also be reduced to a one-dimensional form, unifying existing derivations into a single expression. This result is used to investigate the potential enhancement of fusion reactivity due to the combination of beam and temperature anisotropies. For relevant parameters in fusion energy, the enhancement factor can be larger than 20\%, which is particularly significant for proton-boron (p-B11) fusion, as this factor can have a significant impact on the Lawson fusion gain criteria.
↳ physics.plasm-phnucl-thPlasma Phys.Control.Fusion(2023)·1 citation
09
Particle-dimer approach for the Roper resonance in a finite volume
Daniel Severt🇩🇪 · Maxim Mai🇩🇪 · Ulf-G. Meißner🇩🇪
We propose a new finite-volume approach which implements two- and three-body dynamics in a transparent way based on an Effective Field Theory Lagrangian. The formalism utilizes a particle-dimer picture and formulates the quantization conditions based on the self-energy of the decaying particle. The formalism is studied for the case of the Roper resonance, using input from lattice QCD and phenomenology. Finally, finite-volume energy eigenvalues are predicted and compared to existing results of lattice QCD calculations. This crucially provides initial guidance on the necessary level of precision for the finite-volume spectrum.
↳ hep-lathep-phnucl-thJHEP(2023)·28 citations
10
Tracing the emergence of collectivity phenomena in small systems
B Schenke🇺🇸 · S Schlichting🇩🇪 · P Singh🇫🇮
We study initial state momentum correlations and event-by-event geometry in p+Pb collisions at $s = 5.02 TeV$ by following the approach of extending the IP-Glasma model to 3D using JIMWLK rapidity evolution. On examining the non-trivial rapidity dependence of the observables, we find that the geometry is correlated over large rapidity intervals, while the initial state momentum correlations have a relatively short range in rapidity. Based on our results, we discuss implications for the relevance of both effects in explaining the origin of collective phenomena in small systems.
↳ hep-phnucl-thActa Phys.Polon.Supp.(2023)·2 citations
11
Neutrino-tagged jets at the Electron-Ion Collider
Miguel Arratia🇺🇸 · Zhong-Bo Kang🇺🇸 · Sebouh J. Paul🇺🇸 · Alexei Prokudin🇺🇸 · Felix Ringer🇺🇸 · Fanyi Zhao🇺🇸
We explore the potential of jet observables in charged-current deep-inelastic scattering (CC DIS) events at the future Electron-Ion Collider (EIC). Tagging jets with a recoiling neutrino, which can be identified by the event's missing transverse momentum, will allow for flavor-sensitive measurements of Transverse Momentum Dependent parton distribution functions (TMDs). We present the first predictions for transverse-spin asymmetries in azimuthal neutrino-jet correlations and hadron-in-jet measurements. We study the kinematic reach and the precision of these measurements and explore their feasibility using parameterized detector simulations. We conclude that jet production in CC DIS, while challenging in terms of luminosity requirements, will complement the EIC experimental program to study the three-dimensional structure of the nucleon encoded in TMDs.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·17 citations
12
Jet quenching for heavy flavors in $AA$ and $pp$ collisions
B.G. Zakharov🇷🇺
We perform a global analysis of experimental data on jet quenching for heavy flavors for scenarios with and without quark-gluon plasma formation in $pp$ collisions. We find that the theoretical predictions for the nuclear modification factor $R_{AA}$ for heavy flavors at the LHC energies are very similar for these scenarios, and the results for $R_{AA}$ and $v_{2}$ agree reasonably with the LHC data. The agreement with data at the RHIC top energy becomes somewhat better for the intermediate scenario, in which the quark-gluon plasma formation in $pp$ collisions occurs only at the LHC energies. Our fits to heavy flavor $R_{AA}$ show that description of jet quenching for heavy flavors requires somewhat bigger $α_{s}$ than data on jet quenching for light hadrons.
↳ hep-phnucl-thJ.Exp.Theor.Phys.(2023)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE