Nuclear Theory·nucl-th

Tuesday·April 23, 2024

10 papers—6 primary·4 cross-listed

01
[Submitted on 20 Apr 2024]
The axially-deformed relativistic quasiparticle random phase approximation based on point-coupling interactions
A. Ravlić🇺🇸 · T. Nikšić🇭🇷 · Y. F. Niu🇨🇳 · P. Ring🇩🇪 · N. Paar🇭🇷
Collective nuclear excitations, like giant resonances, are sensitive to nuclear deformation, as evidenced by alterations in their excitation energies and transition strength distributions. A common theoretical framework to study these collective modes, the random-phase approximation (RPA), has to deal with large dimensions spanned by all possible particle-hole configurations satisfying certain symmetries. This work aims to establish a new theoretical framework to study the impact of deformation on spin-isospin excitations, that can provide fast and reliable solutions of the RPA equations. The nuclear ground state is determined with the axially-deformed relativistic Hartree-Bogoliubov (RHB) model based on relativistic point-coupling energy density functionals (EDFs). To study the excitations in the charge-exchange channel, an axially-deformed proton-neutron relativistic quasiparticle RPA (pnRQRPA) is developed in the linear response approach. After benchmarking the axially-deformed pnRQRPA in the spherical limit, a study of spin-isospin excitations including Fermi, Gamow-Teller (GT), and Spin-Dipole (SD) is performed for selected $p f$ -shell nuclei. For GT transitions, it is demonstrated that deformation leads to considerable fragmentation of the strength function. A mechanism inducing the fragmentation is studied by decomposing the total strength to different projections of total angular momentum $K$ and constraining the nuclear shape to either spherical, prolate or oblate. A similar fragmentation is also observed for SD transitions, although somewhat moderated by the complex structure of these transitions, while the Fermi strength is almost shape-independent. The axially-deformed pnRQRPA introduced in this work opens perspectives for future studies of deformation effects on astrophysically relevant weak interaction processes, in particular beta decay and electron capture.
Comments:
22 pages, 11 figures, submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2404.13266 [pdf]
PRC(2024)·9 citations
02
[Submitted on 21 Apr 2024]
Light and hyper nuclei formation at $s_{NN} =$ 3 GeV Au+Au collisions using Wigner coalescence approach
L. K. Liu🇨🇳 · C. L. Hu🇨🇳 · X. H. He🇨🇳 · S. S. Shi🇨🇳 · G. N. Xie🇨🇳
The production of light nuclei and hyper-nuclei in heavy-ion collisions, particularly at high baryon density, is crucial for understanding the dynamical evolution of the collision system and exploring the internal state of nuclear matter of compacted stellar object. Despite being a topic of ongoing debate, an improved theoretical understanding is necessary. In this work, production of light nuclei ( $d$ , $t$ , $^{3}$ He, $^{4}$ He) and hyper-nuclei ( $_{Λ}^{3}$ H, $_{Λ}^{4}$ H) was investigated using the JAM microscopic transport model combined with an afterburner coalescence process at $s_{NN} =$ 3 GeV Au+Au collisions. The formation of a specific nucleus during the coalescence process is determined by its Wigner function. The comparison of the calculations for $p_{T}$ spectra, average $p_{T}$ , and rapidity distributions to the measurements from the STAR experiment was performed. We investigated the dynamic information carried by light nuclei and determined the averaged spatial distance $⟨ Δ R ⟩$ and momentum difference $⟨ Δ P ⟩$ of constituent nucleons ( $Λ$ ) for each nucleus species.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.13582 [pdf]
PLB(2024)·7 citations
03
[Submitted on 21 Apr 2024]
Radial and orbital decomposition of charge radii of Ca nuclei:Comparative study of Skyrme and Fayans functionals
T. Inakura · N. Hinohara · H. Nakada
We investigate the charge and point-proton radii of the Ca nuclei in detail in the density functional theory framework. As the Fayans energy density functional provides characteristic $N$ -dependence, successfully describing the parabolic behavior of the differential charge radii in $20 \leq N \leq 28$ , we pose our particular focus on its physics origin, by decomposing them into the radial and orbital contributions. The results are compared with those from the Skyrme plus usual pairing functional, which is taken as a representative of the functionals having normal pairing channels. We point out that, because the enhancement of the differential charge radii in $N < 20$ with the Fayans functional, which is contradictory with the data, has the origin parallel to the parabolic behavior in $20 \leq N \leq 28$ , it is significant to describe both $N$ regions simultaneously.
Comments:
12 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.13635 [pdf]
PRC(2024)·5 citations
04
[Submitted on 22 Apr 2024]
Fission barriers with Weizsäcker-Skyrme mass model
Ning Wang · Liu Min
Based on Weizsäcker-Skyrme (WS4) mass model, the fission barriers of nuclei are systematically studied. Considering the shell corrections, the macroscopic deformation energy and a phenomenological residual correction, the fission barrier heights for nuclei with $Z ⩾ 82$ can be well described, with an rms deviation of 0.481 MeV with respect to 71 empirical barrier heights. In addition to the shell correction at the ground state, the shell correction at the saddle point and its relative value are also important for both deformed nuclei and spherical nuclei. The fission barriers for nuclei far from the $β$ -stability line and super-heavy nuclei are also predicted with the proposed approach.
Comments:
7 figures, ao appear in Chin. Phys. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.14014 [pdf]
CPC(2024)·5 citations
05
[Submitted on 22 Apr 2024]
Ab initio description of monopole resonances in light- and medium-mass nuclei: III. Moments evaluation in ab initio PGCM calculations
Andrea Porro🇩🇪 · Thomas Duguet🇫🇷 · Jean-Paul Ebran🇫🇷 · Mikael Frosini🇫🇷 · Robert Roth🇩🇪 · Vittorio Somà🇫🇷
The paper is the third of a series dedicated to the ab initio description of monopole giant resonances in mid-mass closed- and open-shell nuclei via the so-called projected generator coordinate method. The present focus is on the computation of the moments $m_{k}$ of the monopole strength distribution, which are used to quantify its centroid energy and dispersion. First, the capacity to compute low-order moments via two different methods is developed and benchmarked for the $m_{1}$ moment. Second, the impact of the angular momentum projection on the centroid energy and dispersion of the monopole strength is analysed before comparing the results to those obtained from consistent quasi-particle random phase approximation calculations. Next, the so-called energy weighted sum rule (EWSR) is investigated. First, the appropriate ESWR in the center-of-mass frame is derived analytically. Second, the exhaustion of the intrinsic EWSR is tested in order to quantify the (unwanted) local-gauge symmetry breaking of the presently employed chiral effective field theory ( $χ$ EFT) interactions. Finally, the infinite nuclear matter incompressibility associated with the employed $χ$ EFT interactions is extracted by extrapolating the finite-nucleus incompressibility computed from the monopole centroid energy.
Comments:
19 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.14154 [pdf]
EPJA(2024)·13 citations
06
[Submitted on 22 Apr 2024]
$Λ$ polarization in very high energy heavy ion collisions as a probe of the Quark-Gluon Plasma formation and properties
Andrea Palermo🇺🇸 · Eduardo Grossi🇮🇹 · Iurii Karpenko🇨🇿 · Francesco Becattini🇮🇹
We have studied the spin polarization of $Λ$ hyperons in heavy ion collisions at center-of-mass energies $s_{N N} = 200$ GeV and $s_{N N} = 5.02$ TeV carried out at RHIC and LHC colliders. We have calculated the mean spin vector at local thermodynamic equilibrium, including all known first-order terms in the gradients of the thermo-hydrodynamic fields, assuming that the hadronization hypersurface has a uniform temperature. We have also included the feed-down contributions to the polarization of $Λ$ stemming from the decays of polarized $Σ^{*}$ and $Σ^{0}$ hyperons. The obtained results are in good agreement with the data. In general, the component of the spin vector along the global angular momentum, orthogonal to the reaction plane, shows strong sensitivity to the initial longitudinal flow velocity. Furthermore, the longitudinal component of the spin vector turns out to be very sensitive to the bulk viscosity of the plasma at the highest LHC energy. Therefore, the azimuthal dependence of spin polarization can effectively constrain the initial hydrodynamic conditions and the transport coefficients of the Quark Gluon Plasma.
Comments:
15 pages, 10 figures. V4: Modified Glissando IS. Polarization computed in more centralities
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
2404.14295 [pdf]
EPJC(2024)·47 citations
07
[Submitted on 20 Apr 2024] (cross-list from physics.atom-ph)
Isotope-shift factors with quantum electrodynamics effects for many-electron systems: A study of the nuclear charge radius of $^{26 m}$ Al
Leonid V. Skripnikov · Sergey D. Prosnyak · Aleksei V. Malyshev · Michail Athanasakis-Kaklamanakis · Alex Jose Brinson · Kei Minamisono · Fabian C. Pastrana Cruz · Jordan Ray Reilly · Brooke J. Rickey · Ronald. F. Garcia Ruiz
A method for calculating the field shift contribution to isotope shifts in many-electron atoms, incorporating quantum electrodynamics (QED) effects, is introduced. We also implement the model QED approach to incorporate QED contribution to the nuclear recoil effect at the high-order correlation effects treatment level. The proposed computational scheme is used to revise the value of the root-mean-square (rms) nuclear charge radius of the isomer of aluminium-26, $^{26 m}$ Al. This radius is important for the global analysis of the $V_{u d}$ element of the Cabibbo-Kobayashi-Maskawa matrix. The difference in mean-square nuclear charge radii of $^{27}$ Al and $^{26 m}$ Al, obtained by combining the calculated atomic factors with recently measured isotope shift (IS) of the $3 s^{2} 3 p^{2} P_{3/2} \to 3 s^{2} 4 s^{2} S_{1/2}$ transition in Al, is $0.443 (44) (19) fm^{2}$ , where the first and second uncertainties are experimental and theoretical ones, respectively. The latter is reduced by a factor of 4 with respect to the previous study. Using this value and the known value of the rms charge radius of $^{27}$ Al, the resultant value $R_{c} (^{26 m}$ Al) = 3.132(10)~fm is obtained. With the improved accuracy of the calculated IS factors the error in $R_{c} (^{26 m}$ Al) is now dominated by the experimental uncertainty. Similar revision of rms charge radii is made for the $^{28}$ Al, $^{29}$ Al, $^{30}$ Al, $^{31}$ Al and $^{32}$ Al isotopes using existing IS measurements. Additionally, atomic factors are computed for the $3 s^{2} 3 p^{2} P_{3/2} \to 3 s^{2} 4 s^{2} S_{1/2}$ , $3 s^{2} 3 p^{2} P_{1/2} \to 3 s^{2} 5 s^{2} S_{1/2}$ and $3 s^{2} 3 p^{2} P_{3/2} \to 3 s^{2} 5 s^{2} S_{1/2}$ transitions in Al, which can be used in future experimental studies.
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); physics.chem-ph (physics.chem-ph)
arXiv:
2404.13369 [pdf]
PRA(2024)·9 citations
08
[Submitted on 22 Apr 2024] (cross-list from hep-ph)
Local univalence versus stability and causality in hydrodynamic models
Roya Heydari🇮🇷 · Farid Taghinavaz🇮🇷
Our main objective is to compare the analytic properties of hydrodynamic series with the stability and causality conditions applied to hydrodynamic modes. Analyticity, in this context, implies that the hydrodynamic series behaves as a univalent or single-valued function. Stability and causality adhere to physical constraints where hydrodynamic modes neither exhibit exponential growth nor travel faster than the speed of light. Through an examination of various hydrodynamic models, such as the Muller-Israel-Stewart (MIS) and the first-order hydro models like the BDNK (Bemfica-Disconzi-Noronha-Kovtun) model, we observe no new restrictions stemming from the analyticity limits in the shear channel of these models. However, local univalence is maintained in the sound channel of these models despite the global divergence of the hydrodynamic series. Notably, differences in the sound equations between the MIS and BDNK models lead to distinct analyticity limits. The MIS model's sound mode remains univalent at high momenta within a specific transport range. Conversely, in the BDNK model, the univalence of the sound mode extends to intermediate momenta across all stable and causal regions. Generally, the convergence radius is independent of univalence and the given dispersion relation predominantly influences their correlation. For second-order frequency dispersions, the relationship is precise, i.e. within the convergence radius, the hydro series demonstrates univalence. However, with higher-order dispersions, the hydro series is locally univalent within certain transport regions, which may fall within or outside the stable and causal zones.
Comments:
24 pages, 10 figures, comments are welcome
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2404.14091 [pdf]
1 citation
09
[Submitted on 22 Apr 2024] (cross-list from hep-ph)
Topological susceptibility and axion potential in two-flavor superconductive quark matter
Fabrizio Murgana🇮🇹 · David E. Alvarez Castillo🇵🇱 · Ana G. Grunfeld🇦🇷 · Marco Ruggieri🇮🇹
We study the potential of the axion, $a$ , of Quantum Chromodynamics, in the two-flavor color superconducting phase of cold and dense quark matter. We adopt a Nambu-Jona-Lasinio-like model. Our interaction contains two terms, one preserving and one breaking the $U (1)_{A}$ symmetry: the latter is responsible of the coupling of axions to quarks. We introduce two quark condensates, $h_{L}$ and $h_{R}$ , describing condensation for left-handed and right-handed quarks respectively; we then study the loci of the minima of the thermodynamic potential, $Ω$ , in the $(h_{L}, h_{R})$ plane, noticing how the instanton-induced interaction favors condensation in the scalar channel when the $θ -$ angle, $θ = a / f_{a}$ , vanishes. Increasing $θ$ we find a phase transition where the scalar condensate rotates into a pseudo-scalar one. We present an analytical result for the topological susceptibility, $χ$ , in the superconductive phase, which stands both at zero and at finite temperature. Finally, we compute the axion mass and its self-coupling. In particular, the axion mass $m_{a}$ is related to the full topological susceptibility via $χ = m_{a}^{2} f_{a}^{2}$ , hence our result for $χ$ gives an analytical result for $m_{a}$ in the superconductive phase of high-density Quantum Chromodynamics.
Comments:
Few references added, few typos corrected, upgraded Fig.3 and Fig.6. Version accepted for publication on Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2404.14160 [pdf]
PRD(2024)·11 citations
10
[Submitted on 22 Apr 2024] (cross-list from physics.plasm-ph)
PM2D: A parallel GPU-based code for the kinetic simulation of laser plasma instabilities in large scale plasmas
Hanghang Ma · Liwei Tan · Suming Weng · Wenjun Ying · Zhengming Sheng · Jie Zhang
Laser plasma instabilities (LPIs) have significant influences on the laser energy deposition efficiency, hot electron generation, and uniformity of irradiation in inertial confined fusion (ICF). In contrast to theoretical analysis of linear development of LPIs, numerical simulations play a more and more important role in revealing the complex physics of LPIs. Since LPIs are typically a three-wave coupling process, the precise kinetic simulation of LPIs requires to resolve the laser period (around one femtosecond) and laser wavelength (less than one micron). In this paper, a full wave fluid model of LPIs is constructed and numerically solved by the particle-mesh method, where the plasma is described by macro particles that can move across the mesh grids freely. Based upon this model, a two-dimensional (2D) GPU code named PM2D is developed. It can simulate the kinetic effects of LPIs self-consistently as normal particle-in-cell (PIC) codes. Moreover, as the physical model adopted in the PM2D code is specifically constructed for LPIs, the required macro particles per grid in the simulations can be largely reduced and thus overall simulation cost is considerably reduced comparing with typical PIC codes. Moreover, the numerical noise in our PM2D code is much lower, which makes it more robust than PIC codes in the simulation of LPIs for the long-time scale above 10 picoseconds. After the distributed computing is realized, our PM2D code is able to run on GPU clusters with a total mesh grids up to several billions, which meets the typical requirements for the simulations of LPIs at ICF experimental scale with reasonable cost.
Comments:
37 pages,14 figures
Subjects:
Plasma Physics (physics.plasm-ph); Nuclear Theory (nucl-th)
arXiv:
2404.14293 [pdf]
Comput.Phys.Commun.(2024)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE