Nuclear Theory·nucl-th

Tuesday·March 19, 2024

12 papers—6 primary·6 cross-listed

01
Simulations of stochastic fluid dynamics near a critical point in the phase diagram
Chandrodoy Chattopadhyay🇺🇸 · Josh Ott🇺🇸 · Thomas Schaefer🇺🇸 · Vladimir V. Skokov🇺🇸
We present simulations of stochastic fluid dynamics in the vicinity of a critical endpoint belonging to the universality class of the Ising model. This study is motivated by the challenge of modeling the dynamics of critical fluctuations near a conjectured critical endpoint in the phase diagram of Quantum Chromodynamics (QCD). We focus on the interaction of shear modes with a conserved scalar density, which is known as model H. We show that the observed dynamical scaling behavior depends on the correlation length and the shear viscosity of the fluid. As the correlation length is increased or the viscosity is decreased we observe a cross-over from the dynamical exponent of critical diffusion, $z ≃ 4$ , to the expected scaling exponent of model H, $z ≃ 3$ . We use our method to investigate time-dependent correlation function of non-Gaussian moments $M^{n} (t)$ of the order parameter. We find that the relaxation time depends in non-trivial manner on the power $n$ .
nucl-thhep-phphysics.flu-dynPRL(2024)·29 citations
02
Systematic shell-model study of structure and isomeric states in $^{204 - 213}$ Bi isotopes
Sakshi Shukla · Praveen C. Srivastava · Deepak Patel
In this work, we have performed systematic shell-model calculations for Bi isotopes with $A =$ 204-213 using KHH7B and KHM3Y effective interactions. We have reported yrast and non-yrast shell-model states corresponding to the available experimental data. From the comparison with the experimental data, we could assign spin and parity of several unconfirmed states. We have also calculated electromagnetic properties and compared them with the available experimental data and predicted where experimental data are not available. This study also includes a detailed discussion of multiple isomeric states based on computed shell-model configurations and their respective half-lives.
nucl-thnucl-exJ.Phys.G(2024)·4 citations
03
Probing multi-particle bunching from intermittency analysis in relativistic heavy-ion collisions
Valeria Zelina Reyna Ortiz🇵🇱 · Maciej Rybczynski🇵🇱 · Zbigniew Wlodarczyk🇵🇱
It has been demonstrated that factorial moments analysis in dependence from the size of phase-space cells (when the latter is decreased but is still considerably large), exhibits sensitivity to particle bunching within a system situated in the two-dimensional cell. Based on recent findings concerning fluctuations in charge particle density observed in central Au + Au collisions at various energies ranging from $s_{N N}$ = 7.7 to 200 GeV at RHIC/STAR, it is proposed that analyzing factorial moments in relativistic heavy-ion collisions could serve as a method to investigate density fluctuations linked to correlation phenomena. Our understanding of particle production mechanisms may be enriched by using factorial moments analysis to gain new information contained in them that was previously unavailable.
nucl-thhep-phNPA(2025)·1 citation
04
Characteristics of the fission fragments in the three-body model of binary fission
V. Yu. Denisov
The evaluated nuclide yields, fragment mass and charge distributions, and averaged total kinetic energy of fission fragments for the neutron-induced fission of 30 actinide nuclei are well described in the new model, which considers the fissioning scission system consisting of two heavy fragments and an alpha-particle between them. The alpha-particle has its origin in the neck nucleons. The yield of fission fragments in the model is linked to the number of states over the barrier of the saddle point, which is between the contacting and well-separated fission fragments. The alpha-particle is fused with the nearest heavy fragment after passing the saddle point, therefore, two final fragments appear during fission. The quadrupole deformations of heavy fragments are taken into account in the model. The fragment yields depend on the heights of corresponding saddle points and the values of the equilibrium quadrupole deformation of fragments.
nucl-thEPJ Web Conf.(2024)·1 citation
05
Variational calculations of symmetric nuclear matter and pure neutron matter with the tensor-optimized Fermi Sphere (TOFS) method: many-body effects and short-range correlation
Taiichi Yamada
The equations of state for symmetric nuclear matter and pure neutron matter are investigated with the tensor-optimized Fermi Sphere method (TOFS) up to the density $ρ = 0.5$ ~fm $^{- 3}$ . This method is based on a linked-cluster expansion theorem, and the energy per particle of nuclear matter ( $E / A$ ) is calculated variationally with respect to the correlated nuclear matter wave function. We can study the density dependence of the many-body terms arising from the operator products, which contribute to $E / A$ . In order to clarify the relation between the many-body effects and short-range correlation, we take the spin-isospin dependent central {\it NN} interaction with a few GeV repulsion in the inner region. The EOS obtained by the TOFS method is reasonably reproduced, compared with other \textit{ab initio} many-body methods. We found that the many-body terms from the 2-body to 6-body ones) give sizable effects on $E / A$ at higher density, and they play an important role in nuclear matter.
nucl-thEPJA(2024)·1 citation
06
Effects of strangeness on the chiral pseudocritical line
Mahammad Sabir Ali🇮🇳 · Deeptak Biswas🇮🇳 · Amaresh Jaiswal🇮🇳 · Hiranmaya Mishra🇮🇳
Within a 2+1 flavor Nambu\textendash Jona-Lasinio model, we calculate the curvature coefficients and check them against available lattice QCD estimations. With the observation that the flavor mixing due to the `t Hooft determinant term significantly affects the $κ_{2}^{S}$ , we explore the effect of $μ_{S}$ on the $T - μ_{B}$ crossover lines. With the novel determination of negative $κ_{2}^{B}$ at large $μ_{S}$ , we advocate the importance of studying the same in lattice QCD.
nucl-thhep-latPRD(2024)·9 citations
07
Quark anomalous magnetic moment in an extreme magnetic background from perturbative QCD
Eduardo S. Fraga🇧🇷 · Leticia F. Palhares🇧🇷 · Cristian Villavicencio🇨🇱
We compute the one-loop QCD correction to the photon-quark-antiquark vertex in an extremely strong magnetic background, i.e., one in which $e B$ is much larger than all other mass scales. We resort to the lowest-Landau level approximation, and consider on shell fermions. We find that the total magnetic moment is such that the anomalous magnetic moment contributes to the electric part $\sim i E_{3} σ_{3}$ , the other contributions to $B \cdot σ$ and $i E \cdot σ_{⊥}$ being completely suppressed. We show results for the anomalous magnetic moment of quarks up and down, scaled by their values in the vacuum, as a function of the external magnetic field, considering dressed gluons and a renormalization scale $μ_{MS} = ∣ e B ∣$ .
↳ hep-phnucl-thPRD(2024)·8 citations
08
Evolution of chirality from transverse wobbling in $^{135}$ Pr
N. Sensharma · U. Garg · Q. B. Chen · S. Frauendorf · S. Zhu · J. Arroyo · A. D. Ayangeakaa · D. P. Burdette · M. P. Carpenter · P. Copp · J. L. Cozzi · S. S. Ghugre and 11 other authors
Chirality is a distinct signature that characterizes triaxial shapes in nuclei. We report the first observation of chirality in the nucleus $^{135}$ Pr using a high-statistics Gammasphere experiment with the $^{123}$ Sb( $^{16}$ O,4n) $^{135}$ Pr reaction. Two chiral-partner bands with the configuration $π (1 h_{11/2})^{1} \otimes ν (1 h_{11/2})^{- 2}$ have been identified in this nucleus. Angular distribution analyses of the $Δ I = 1$ transitions connecting the two bands reveal a dominant dipole character, and quasiparticle triaxial rotor model calculations show good agreement with the data. Since the simultaneous observation of chirality and transverse wobbling in $^{135}$ Pr relies critically on these angular distribution results, we also address and refute the experimental and theoretical criticisms raised in a recent work by Lv et al., presenting additional evidence that further strengthens our interpretation. This marks the first observation of both hallmarks of triaxiality-chirality and wobbling-in the same nucleus.
↳ nucl-exnucl-thPRC(2026)·2 citations
09
Revisiting the excitation of the low-lying $^{181 m}$ Ta isomer in optical laser-generated plasma
Simone Gargiulo · Ivan Madan · Benoit Truc · Paolo Usai · Kjeld Beeks · Veronica Leccese · Giovanni Maria Vanacore · Fabrizio Carbone
The excitation of the $^{181 m}$ Ta isomer in the laser-plasma scenario was claimed to have been observed more than two decades ago. However, the reported experimental findings - and the respective high excitation rate - were later questioned as they could not be reproduced theoretically. The controversy has remained open ever since. In this work, we reinvestigate both theoretically and experimentally the $^{181 m}$ Ta nuclear excitation in an optical laser-generated plasma. Experimentally we have found no evidence for such an excitation process as consistently predicted by previous and our theoretical models.
↳ nucl-exnucl-thPRL(2024)·4 citations
10
Detecting superfluid transition in the pulsar core
Partha Bagchi (1) · Biswanath Layek (2) · Dheeraj Saini (3) · Anjishnu Sarkar (3) · Ajit M. Srivastava (4) · Deepthi Godaba Venkata (2) ((1) School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar, India, (2) Department of Physics, Birla Institute of Technology and Science, Pilani-333031, India, (3) Physics Department, The LNM Institute of Information Technology, Jaipur-302031, India, (4) Institute of Physics, Sachivalaya Marg, Bhubaneswar-751005, India)
It is believed that the core of a neutron star can be host to various novel phases of matter, from nucleon superfluid phase to exotic high baryon density quantum chromodynamics (QCD) phases. Different observational signals for such phase transitions have been discussed in the literature. Here, we point out a unique phenomenon associated with phase transition to a superfluid phase, which may be the nucleon superfluid phase or a phase like the CFL phase, allowing for superfluid vortices. In any superfluid phase transition, a random network of vortices forms via the so-called Kibble-Zurek mechanism, which eventually mostly decays away, finally leaving primarily vortices arising from the initial angular momentum of the core. This transient, random vortex network can have a non-zero net angular momentum for the superfluid component, which will generally be oriented in an arbitrary direction. This is in contrast to the final vortices, which arise from initial rotation and hence have the initial angular momentum of the neutron star. The angular momentum of the random vortex network is balanced by an equal and opposite angular momentum in the normal fluid due to the conservation of angular momentum, thereby imparting an arbitrarily oriented angular momentum component to the outer shell of the neutron star. This will affect the pulse timing and pulse profile of a pulsar. These changes in the pulses will decay away in a characteristic manner such that the random vortex network decays, obeying specific scaling laws leading to universal features for the detection of superfluid transitions occurring in a pulsar core.
↳ astro-ph.HEhep-phnucl-thMNRAS(2024)·2 citations
11
Nonlinear Pulse Dynamics in a Magnetized and Nonextensive Quark-Gluon Plasma
Trambak Bhattacharyya · Md Hasanujjaman
We investigate the propagation of nonlinear energy density waves in a nonextensive quark-gluon plasma under the influence of a magnetic field using the reductive perturbation technique. For a nonextensive MIT bag equation of state, we obtain the governing equation for the first order perturbation of the energy density. We observe that an increase in the strength of the magnetic field results in the localization of the waves.
↳ hep-phhep-thnucl-th0 citations
12
Isotropization of a longitudinally expanding system of scalar fields in the 2PI formalism
François Gelis🇫🇷 · Sigtryggur Hauksson🇫🇷
Motivated by isotropization of QCD matter in the initial stages of heavy-ion collisions, we consider a system of scalar fields that undergoes a boost invariant longitudinal expansion. We use the framework of the two-particle irreducible (2PI) effective action, which is close to the underlying quantum field theory, and resum self-energy corrections up to three loops. The resulting 2PI equations of motion are expressed in terms of the Milne coordinates to account for longitudinal expansion. By solving numerically these equations of motion, we can extract the occupation density and the effective mass generated by in-medium interactions. At the largest values of the coupling considered in this study, we observe the onset of isotropization both in the occupation number and in the momentum dependence of the effective mass.
↳ hep-phnucl-thJHEP(2024)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE