Nuclear Theory·nucl-th

Thursday·February 11, 2021

11 papers—5 primary·6 cross-listed

01
[Submitted on 9 Feb 2021]
The islands of shape coexistence within the Elliott and the proxy-SU(3) Models
Andriana Martinou🇬🇷 · Dennis Bonatsos🇬🇷 · T. J. Mertzimekis🇬🇷 · K. E. Karakatsanis🇬🇷 · I.E. Assimakis🇬🇷 · S. K. Peroulis🇬🇷 · S. Sarantopoulou🇬🇷 · N. Minkov🇧🇬
A novel dual-shell mechanism for the phenomenon of shape coexistence in nuclei within the Elliott SU(3) and the proxy-SU(3) symmetry is proposed for all mass regions. It is supposed, that shape coexistence is activated by large quadrupole-quadrupole interaction and involves the interchange among the spin-orbit (SO) like shells within nucleon numbers 6-14, 14-28, 28-50, 50-82, 82-126, 126-184, which are being described by the proxy-SU(3) symmetry, and the harmonic oscillator (HO) shells within nucleon numbers 2-8, 8-20, 20-40, 40-70, 70-112, 112-168 of the Elliott SU(3) symmetry. The outcome is, that shape coexistence may occur in certain islands on the nuclear map. The dual-shell mechanism predicts without any free parameters, that nuclei with proton number (Z) or neutron number (N) between 7-8, 17-20, 34-40, 59-70, 96-112, 146-168 are possible candidates for shape coexistence. In the light nuclei the nucleons flip from the HO shell to the neighboring SO-like shell, which means, that particle excitations occur. For this mass region, the predicted islands of shape coexistence, coincide with the islands of inversion. But in medium mass and heavy nuclei, in which the nucleons inhabit the SO-like shells, shape coexistence is accompanied by a merging of the SO-like shell with the open HO shell. The shell merging can be accomplished by the outer product of the SU(3) irreps of the two shells and represents the unification of the HO shell with the SO-like shell.
Comments:
31 pages, 25 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2102.05133 [pdf]
EPJA(2021)·55 citations
02
[Submitted on 10 Feb 2021]
Non-flow effects in correlation between harmonic flow and transverse momentum in nuclear collisions
Chunjian Zhang🇺🇸 · Arabinda Behera🇺🇸 · Somadutta Bhatta🇺🇸 · Jiangyong Jia🇺🇸
A large anti-correlation signal between elliptic flow $v_{2}$ and average transverse momentum $[p_{T}]$ was recently measured in small collision systems, consistent with a final-state hydrodynamic response to the initial geometry. This negative $v_{2}$ - $[p_{T}]$ correlation was predicted to change to positive correlation for events with very small charged particle multiplicity $N_{ch}$ due to initial-state momentum anisotropies of the gluon saturation effects. However, the role of non-flow correlations is expected to be important in these systems, which is not yet studied. We estimate the non-flow effects in $pp$ , $p$ Pb and peripheral PbPb collisions using {\tt Pythia} and {\tt Hijing} models, and compare them with the experimental data. We show that the non-flow effects are largely suppressed using the rapidity-separated subevent cumulant method (details of the cumulant framework are also provided). The magnitude of the residual non-flow is much less than the experimental observation in the higher $N_{ch}$ region, supporting the final-state response interpretation. In the very low $N_{ch}$ region, however, the sign and magnitude of the residual non-flow depend on the model details. Therefore, it is unclear at this moment whether the sign change of $v_{2}$ - $[p_{T}]$ can serve as evidence for initial state momentum anisotropies predicted by the gluon saturation.
Comments:
9 pages, 8 figures including an appendix, replace with published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2102.05200 [pdf]
PLB(2021)·27 citations
03
[Submitted on 10 Feb 2021]
Constraints on the Symmetry Energy from PREX-II in the Multimessenger Era
Tong-Gang Yue🇨🇳 · Lie-Wen Chen🇨🇳 · Zhen Zhang🇨🇳 · Ying Zhou🇨🇳
The neutron skin thickness $Δ r_{np}$ of heavy nuclei is essentially determined by the symmetry energy density slope $L (ρ)$ at $ρ_{c} = 0.11 fm^{- 3} \approx 2/3 ρ_{0}$ ( $ρ_{0}$ is nuclear saturation density), roughly corresponding to the average density of finite nuclei. The PREX collaboration recently reported a model-independent extraction of $Δ r_{np}^{208} = 0.283 \pm 0.071$ fm for the $Δ r_{np}$ of $^{208}$ Pb, suggesting a rather stiff symmetry energy $E_{sym} (ρ)$ with $L (ρ_{c}) \geq 52$ MeV. We show that the $E_{sym} (ρ)$ cannot be too stiff and $L (ρ_{c}) \leq 73$ MeV is necessary to be compatible with (1) the ground-state properties and giant monopole resonances of finite nuclei, (2) the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities from flow data in heavy-ion collisions, (3) the largest neutron star (NS) mass reported so far for PSR J0740+6620, (4) the NS tidal deformability extracted from gravitational wave signal GW170817 and (5) the mass-radius of PSR J0030+045 measured simultaneously by NICER. This allows us to obtain $52 \leq L (ρ_{c}) \leq 73$ MeV and $0.212 \leq Δ r_{np}^{208} \leq 0.271$ fm, and further $E_{sym} (ρ_{0}) = 34.3 \pm 1.7$ MeV, $L (ρ_{0}) = 83.1 \pm 24.7$ MeV, and $E_{sym} (2 ρ_{0}) = 62.8 \pm 15.9$ MeV. A number of critical implications on nuclear physics and astrophysics are discussed.
Comments:
6 pages, 4 figures. The published PREX-II result used, results updated and discussions added. Accepted version to appear in Physical Review Research as a Letter
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2102.05267 [pdf]
PRResearch(2022)·75 citations
04
[Submitted on 10 Feb 2021]
Baryonic matter and the medium modification of the baryon masses
Nam-Yong Ghim🇰🇷 · Ghil-Seok Yang🇰🇷 · Hyun-Chul Kim🇰🇷 · Ulugbek Yakhshiev🇰🇷
We investigate the properties of baryonic matter within the framework of the in-medium modified chiral soliton model by taking into account the effects of surrounding baryonic environment on the properties of in-medium baryons. The internal parameters of the model are determined based on nuclear phenomenology at nonstrange sector and fitted by reproducing nuclear matter properties near the saturation point. We discuss the equations of state in different nuclear environments such as symmetric nuclear matter, neutron and strange matters. We show that the results for the equations of state are in good agreement with the phenomenology of nuclear matter. We also discuss how the SU(3) baryons masses undergo changes in these various types of nuclear matter.
Comments:
14 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2102.05292 [pdf]
PRC(2021)·5 citations
05
[Submitted on 10 Feb 2021]
Sequential single pion production explaining the dibaryon " $d^{*} (2380)$ " peak
R. Molina · N. Ikeno · E. Oset
We study the two step sequential one pion production mechanism, $n p (I = 0) \to π^{-} pp$ , followed by the fusion reaction $pp \to π^{+} d$ , in order to describe the $n p \to π^{+} π^{-} d$ reaction with $π^{+} π^{-}$ in $I = 0$ , where a narrow peak, so far identified with a " $d (2380)$ " dibaryon, has been observed. We find that the second step $pp \to π^{+} d$ is driven by a triangle singularity that determines the position of the peak of the reaction and the large strength of the cross section. The combined cross section of these two mechanisms produce a narrow peak with the position, width and strength compatible with the experimental observation within the approximations done. This novel interpretation of the peak without invoking a dibaryon explains why the peak is not observed in other reactions where it has been searched for.
Comments:
6 pages, 2 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2102.05575 [pdf]
Chin.Phys.C 47 (2023) 4, 041001

Affiliations

first authorsco-authorsvia INSPIRE

The islands of shape coexistence within the Elliott and the proxy-SU(3) Models

Non-flow effects in correlation between harmonic flow and transverse momentum in nuclear collisions

Constraints on the Symmetry Energy from PREX-II in the Multimessenger Era

Baryonic matter and the medium modification of the baryon masses

Sequential single pion production explaining the dibaryon "d∗(2380)" peak

Affiliations

Sequential single pion production explaining the dibaryon " $d^{*} (2380)$ " peak