Nuclear Theory·nucl-th

Tuesday·March 28, 2023

18 papers—9 primary·9 cross-listed

01
[Submitted on 25 Mar 2023]
Soft dipole resonance in $^{8}$ C and its isospin symmetry with $^{8}$ He
Takayuki Myo · Kiyoshi Kato
We investigate the soft dipole resonance in the proton-rich nucleus $_{6}^{8}$ C $_{2}$ , which is a collective dipole oscillation of four valence protons against the $α$ core,and discuss the isospin symmetry with the mirror nucleus $_{2}^{8}$ He $_{6}$ . We use the $α + N + N + N + N$ five-body cluster model and many-body resonances are obtained using the complex-scaling method. The $1^{-}$ resonance of $_{6}^{8}$ C $_{2}$ is confirmed at the excitation energy of 13 MeV with a large decay width of 24 MeV, and its structure is similar to the soft dipole resonance in $_{2}^{8}$ He $_{6}$ , such as the configuration mixing and the spatial properties. These results indicate a good isospin symmetry in the soft dipole resonances of two nuclei with a common collective excitation of multiproton and multineutron, while the ground states of two nuclei show different properties due to the Coulomb repulsion of valence protons in $_{6}^{8}$ C $_{2}$ , leading to the symmetry breaking. In conclusion, the appearance of the isospin symmetry differs depending on the states of $_{6}^{8}$ C $_{2}$ and $_{2}^{8}$ He $_{6}$ .
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2303.14318 [pdf]
PRC(2023)·5 citations
02
[Submitted on 25 Mar 2023]
Importance of higher orders in opacity in QGP tomography
Stefan Stojku🇷🇸 · Bojana Ilic🇷🇸 · Igor Salom🇷🇸 · Magdalena Djordjevic🇷🇸
We consider the problem of including a finite number of scattering centers in dynamical energy loss and classical DGLV formalism. Previously, either one or an infinite number of scattering centers were considered in energy loss calculations, while attempts to relax such approximations were largely inconclusive or incomplete. In reality, however, the number of scattering centers is generally estimated to be 4-5 at RHIC and the LHC, making the above approximations (a priori) inadequate and this theoretical problem significant for QGP tomography. We derived explicit analytical expressions for dynamical energy loss and DGLV up to the $4^{t h}$ order in opacity, resulting in complex mathematical expressions that were, to our knowledge, obtained for the first time. These expressions were then implemented into an appropriately generalized DREENA framework to calculate the effects of higher orders in opacity on a wide range of high- $p_{⊥}$ light and heavy flavor predictions. Results of extensive numerical analysis, together with interpretations of nonintuitive results, are presented. We find that, for both RHIC and the LHC, higher-order effects on high- $p_{⊥}$ observables are small, and the approximation of a single scattering center is adequate for dynamical energy loss and DGLV formalisms.
Comments:
23 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2303.14527 [pdf]
PRC(2023)·4 citations
03
[Submitted on 26 Mar 2023]
Heavy-Flavour Jets in High-Energy Nuclear Collisions
Sa Wang🇨🇳 · Wei Dai🇨🇳 · Enke Wang🇨🇳 · Xin-Nian Wang🇺🇸 · Ben-Wei Zhang🇨🇳
Reconstructed jets initiated from heavy quarks provide a powerful tool to probe the properties of the quark-gluon plasma (QGP) and to explore the mass hierarchy of jet quenching. In this article, we review the recent theoretical progresses on heavy-flavour jets in high-energy nuclear collisions at the RHIC and LHC. We focus on the yields and substructures of charm and bottom quark jets with jet quenching effect, such as the nuclear modification factors, transverse momentum imbalance, angular correlation, radial profiles, fragmentation functions, the "dead-cone" effect, etc.
Comments:
27 pages, 9 figures. Contribution to the Special Issue "Heavy-Ion Collisions and Multiparticle Production"
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2303.14660 [pdf]
Symmetry(2023)·19 citations
04
[Submitted on 26 Mar 2023]
Constraining nuclear symmetry energy with the charge radii of mirror-pair nuclei
Rong An · Shuai Sun · Li-Gang Cao · Feng-Shou Zhang
The nuclear charge radius plays a vital role in determining the equation of state of isospin asymmetric nuclear matter. Based on the correlation between the differences in charge radii of mirror-partner nuclei and the slope parameter ( $L$ ) of symmetry energy at the nuclear saturation density, an analysis of the calibrated slope parameter $L$ was performed in finite nuclei. In this study, relativistic and non-relativistic energy density functionals were employed to constrain the nuclear symmetry energy through the available databases of the mirror-pair nuclei $^{36}$ Ca- $^{36}$ S, $^{38}$ Ca- $^{38}$ Ar, and $^{54}$ Ni- $^{54}$ Fe. The deduced nuclear symmetry energy was located in the range 29.89-31.85 MeV, and $L$ of the symmetry energy essentially covered the range 22.50-51.55 MeV at the saturation density. Moreover, the extracted $L_{s}$ at the sensitivity density $ρ_{s} = 0.10 fm^{- 3}$ was located in the interval range 30.52-39.76 MeV.
Comments:
23 pages, 6 figures, 2 tables, Published in Nuclear Science and Techniques
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
2303.14667 [pdf]
Nucl.Sci.Tech.(2023)·30 citations
05
[Submitted on 26 Mar 2023]
The astrophysical $S -$ factor and reaction rate for $^{15}$ N( $p, γ$ ) $^{16}$ O within the modified potential cluster model
S. B. Dubovichenko · A. S. Tkachenko · R. Ya. Kezerashvili · N. A. Burkova · B.M. Yeleusheva
We study a radiative $p^{15}$ N capture on the ground state of $^{16}$ O at stellar energies within the framework of a modified potential cluster model (MPCM) with forbidden states, including low-lying resonances. The investigation of the $^{15}$ N( $p, γ_{0}$ ) $^{16}$ O reaction includes the consideration of $^{3} S_{1}$ resonances due to $E 1$ transitions and the contribution of $^{3} P_{1}$ scattering wave in $p$ + $^{15}$ N channel due to $^{3} P_{1} ⟶$ $^{3} P_{0}$ $M 1$ transition. We calculated the astrophysical low-energy $S -$ factor, and extrapolated $S (0)$ turned out to be within $34.7 - 40.4$ keV $\cdot$ b. The important role of the asymptotic constant (AC) for the $^{15}$ N( $p, γ_{0}$ ) $^{16}$ O process with interfering $^{3} S_{1}$ (312) and $^{3} S_{1}$ (962) resonances is elucidated. A comparison of our calculation for $S -$ factor with existing experimental and theoretical data is addressed, and a reasonable agreement is found. The reaction rate is calculated and compared with the existing rates. It has negligible dependence on the variation of AC, but shows a strong impact of the interference of $^{3} S_{1}$ (312) and $^{3} S_{1}$ (962) resonances, especially at temperatures, referring to the CNO Gamow windows. We estimate the contribution of cascade transitions to the reaction rate based on the exclusive experimental data by \textit{Imbriani, et al. 2012}. The reaction rate enhancement due to the cascade transitions is observed from $T_{9} > 0.3$ and reaches the maximum factor $\sim$ \ 1.3 at $T_{9} = 1.3$ . We present the Gamow energy window and a comparison of rates for radiative proton capture reactions $^{12}$ N( $p, γ$ ) $^{13}$ O, $^{13}$ N( $p, γ$ ) $^{14}$ O, $^{14}$ N( $p, γ$ ) $^{15}$ O, and $^{15}$ N( $p, γ$ ) $^{16}$ O obtained in the framework of the MPCM and give temperature windows, prevalence, and significance of each process.
Comments:
17 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2303.14680 [pdf]
CPC(2024)·2 citations
06
[Submitted on 26 Mar 2023]
Can the PREX-2 and CREX results be understood by relativistic mean-field models with the astrophysical constraints?
Tsuyoshi Miyatsu🇰🇷 · Myung-Ki Cheoun🇰🇷 · Kyungsik Kim🇰🇷 · Koichi Saito🇯🇵
We construct new effective interactions using the relativistic mean-field models with the isoscalar- and isovector-meson mixing, $σ^{2} δ^{2}$ and $ω_{μ} ω^{μ} ρ_{ν} ρ^{ν}$ . Taking into account the particle flow data in heavy-ion collisions, the observed mass of PSR J0740 $+$ 6620, and the tidal deformability of a neutron star from binary merger events, GW170817 and GW190814, we study the ground-state properties of finite, closed-shell nuclei, and try to explain the recent results from the PREX-2 and CREX experiments. It is found that the $σ$ -- $δ$ mixing is very powerful to understand the terrestrial experiments and astrophysical observations of neutron stars self-consistently. We can predict the large neutron skin thickness of $^{208}$ Pb, $R_{skin}^{208} = 0.243$ ~fm, using the slope parameter of nuclear symmetry energy, $L = 70$ ~MeV, which is consistent with the PREX-2 result. However, to explain the CREX data, it is preferable to adopt the small value of $L = 20$ ~MeV. It is very difficult to understand the PREX-2 and CREX results simultaneously within relativistic mean-field models.
Comments:
7 pages, 6 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.14763 [pdf]
PLB(2023)·54 citations
07
[Submitted on 27 Mar 2023]
$α$ + core structure described with an additional interaction in the nuclear matter saturation region
M. A. Souza · H. Miyake
In a phenomenological approach, the $α$ + core structure is investigated in the $^{20}$ Ne, $^{44}$ Ti, $^{94}$ Mo, $^{104}$ Te, and $^{212}$ Po nuclei through the local potential model using a double-folding nuclear potential with effective nucleon-nucleon interaction of M3Y + $c_{sat} δ (s)$ type, where the term $c_{sat} δ (s)$ acts only between the saturation regions of $α$ -cluster and core. Properties such as energy levels, $α$ -widths, $B (E 2)$ transition rates, and half-lives are calculated, and good level of agreement with experimental data is obtained in general. It is shown the inclusion of the term $c_{sat} δ (s)$ is determinant for a better description of the experimental energy levels compared to the ground state bands produced with the simple M3Y interaction. The properties calculated for $^{104}$ Te reinforce the superallowed $α$ -decay feature for this nucleus, as indicated in previous studies.
Comments:
13 pages, 6 figures. Accepted for publication in The European Physical Journal A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.14927 [pdf]
EPJA(2023)·4 citations
08
[Submitted on 27 Mar 2023]
Dynamical critical fluctuations near the QCD critical point with hydrodynamic cooling rate
Shian Tang🇨🇳 · Shanjin Wu🇨🇳 · Huichao Song🇨🇳
Within the model A in the Hohenberg's dynamical universality classification, we investigate the critical slowing down effects on the critical fluctuations driven by the expanding quark-gluon plasma, using a trajectory and cooling rate obtained from hydrodynamics. We numerically solved the Langevin dynamics of the non-conserved order parameter field and find that, compared with commonly used Hubble-like expansion, the cooling rate of a realistic hydrodynamic system is pretty large and the associated critical slowing down effects strongly suppress the higher-order cumulants of the order parameter field ({\it e.g.,} $C_{4}$ ). Furthermore, for an evolving system that approaches the critical point, such critical slowing down suppression overcomes the enhancement of the critical fluctuations, which indicates that the largest fluctuations of the order parameter field ({\it i.e.,} $C_{2}$ ) do not necessarily associate with the evolving trajectory closest to the critical point.
Comments:
7 pages,5 figures.Published version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.15017 [pdf]
PRC(2023)·10 citations
09
[Submitted on 27 Mar 2023]
Thermalization at the femtoscale seen in high-energy Pb+Pb collisions
Rupam Samanta🇵🇱 · Somadutta Bhatta🇺🇸 · Jiangyong Jia🇺🇸 · Matthew Luzum🇧🇷 · Jean-Yves Ollitrault🇫🇷
A collision between two atomic nuclei accelerated at a speed close to that of light creates a dense system of quarks and gluons. Interactions among them are so strong that they behave collectively like a droplet of fluid of ten-femtometer size, which expands into the vacuum and eventually fragments into thousands of particles. We report a new manifestation of thermalization in recent data from the Large Hadron Collider. Our analysis is based on results from the ATLAS Collaboration, which has measured the variance of the momentum per particle across Pb+Pb collision events with the same particle multiplicity. This variance decreases steeply over a narrow multiplicity range corresponding to central collisions. We provide a simple explanation of this newly-observed phenomenon: For a given multiplicity, the momentum per particle increases with increasing impact parameter. Since a larger impact parameter goes along with a smaller collision volume, this in turn implies that the momentum per particle increases as a function of density, which is a generic consequence of thermalization. Our analysis provides the first direct evidence of this phenomenon at the femtoscale.
Comments:
8 pages, 3 figures. v2: minor revision
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2303.15323 [pdf]
PRC(2024)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE