Nuclear Theory·nucl-th

Monday·September 23, 2019

7 papers—4 primary·3 cross-listed

01
[Submitted on 20 Sept 2019]
Light Nuclei Production in Au+Au Collisions at $s_{NN}$ = 5-200 GeV from JAM model
Hui Liu🇨🇳 · Dingwei Zhang🇨🇳 · Shu He🇨🇳 · Kai-jia Sun🇺🇸 · Ning Yu🇨🇳 · Xiaofeng Luo🇨🇳
Light nuclei production is sensitive to the baryon density fluctuations and can be used to probe the QCD phase transition in relativistic heavy-ion collisions. In this work, we studied the production of proton, deuteron, triton in central Au+Au collisions at $s_{NN}$ = 5, 7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4 and 200 GeV from a transport model (JAM). Based on the coalescence production of light nuclei, we calculated the energy dependence of rapidity density $d N / d y$ and particle ratios ( $d / p$ , $t / p$ , and $t / d$ ). More importantly, the yield ratio $N_{t} \times N_{p} / N_{d}^{2}$ , which is sensitive to the neutron density fluctuations, shows a flat energy dependence and cannot describe the non-monotonic trend observed by the STAR experiment. Based on the nucleon coalescence, this work can provide constraint and reference to search for the QCD critical point and/or first order phase transition with light nuclei production in future heavy-ion collision experiments.
Comments:
5 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1909.09304 [pdf]
PLB(2020)·57 citations
02
[Submitted on 20 Sept 2019]
Precision calculation of isospin-symmetry-breaking corrections to T=1/2 mirror decays using multi-reference charge-dependent density functional theory
M. Konieczka · P. Bączyk · W. Satuła
We present systematic study of isospin impurities ( $α_{ISB}$ ) to the wave functions of $T = 1/2$ , $11 \leq A \leq 47$ mirror nuclei and the isospin-symmetry-breaking (ISB) corrections ( $δ_{ISB}^{V}$ ) to their ground state vector $β$ -decays using, for the first time, multi-reference charge-dependent density functional theory (MR-DFT) that includes strong-force-rooted class-III interaction adjusted to correct for the Nolen-Schiffer anomaly in nuclear masses. We demonstrate that, unexpectedly, the strong-force-rooted isovector force gives rise to a large systematic increase of $α_{ISB}$ and $δ_{ISB}^{V}$ as compared to the results obtained within MR-DFT that uses Coulomb interaction as the only source of ISB. This, in turn, increases a central value of the $V_{ud}$ element of the CKM matrix extracted from the $T = 1/2$ mirrors bringing it closer to the value obtained form the purely vector superallowed $0^{+} \to 0^{+}$ transitions. In order to compute the value of $V_{ud}$ , we performed precision calculation of the Fermi matrix elements in $A = 19, 21, 35$ , and 37 mirror nuclei using DFT-rooted configuration-interaction model that includes all relevant axially-deformed particle-hole configurations built upon Nilsson orbitals originating from the spherical $s d$ shell. Our calculations yield $∣ V_{ud} ∣ = 0.9736 (16)$ .
Comments:
8 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.09350 [pdf]
PRC(2022)·8 citations
03
[Submitted on 20 Sept 2019]
Shell closure at $N = 34$ and the $^{48}$ Si nucleus
G. Co' · M. Anguiano · A. M. Lallena
By using a non-relativistic independent particle model we investigate the mechanism promoting 34 as new magic number. We carried out Hartree-Fock plus Bardeen-Cooper-Schrieffer and Quasi-particle Random Phase Approximation calculations by consistently using the same finite-range interaction in all the three steps of our approach. We used four Gogny-like interactions, with and without tensor terms. We find that the shell closure for $N = 34$ neutrons appears in isotones with $Z < 26$ protons. The smaller is the proton number, the more evident is the shell closure at $N = 34$ . An ideal nucleus to investigate this effect should be $^{48}$ Si, as it has been recently suggested. However, some discrepancies occur between the results obtained with the four effective interactions we used concerning the position of the two-neutron drip line and, therefore, the existence of $^{48}$ Si. The experimental identification of this nucleus could shed light about the shell evolution in nuclei far from the stability valley and put stringent tests on nuclear structure theories.
Comments:
6 pages, 2 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.09431 [pdf]
IJMPE(2019)·1 citation
04
[Submitted on 20 Sept 2019]
Nuclear chart in covariant density functional theory with dynamical correlations: From Oxygen to Tin
Yi-Long Yang · Ya-Kun Wang
Nuclear masses of even-even nuclei with the proton number $8 \leq Z \leq 50$ (O to Sn isotopes) from proton drip line to neutron drip line are investigated using the triaxial relativistic Hartree-Bogoliubov (RHB) theory with the relativistic density functional PC-PK1, and the dynamical correlation energies (DCEs) associated with the rotational motion and the quadrupole shape vibrational motion are taken into account by the five-dimensional collective Hamiltonian (5DCH) method. The root-mean-square deviation with respect to the experimental masses reduces from 2.50 MeV to 1.59 MeV after the consideration of DCEs. The inclusion of DCEs has little influence on the position of drip lines, and the predicted numbers of bound even-even nuclei between proton and neutron drip lines from O to Sn isotopes are respectively 569 and 564 for the cases with and without DCEs.
Comments:
9 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.09498 [pdf]
CPC(2020)·7 citations
05
[Submitted on 20 Sept 2019] (cross-list from hep-ph)
Reevaluating Reactor Antineutrino Anomalies with Updated Flux Predictions
Jeffrey Berryman🇺🇸 · Patrick Huber🇺🇸
Hints for the existence of a sterile neutrino at nuclear reactors are reexamined using two updated predictions for the fluxes of antineutrinos produced in fissions. These new predictions diverge in their preference for the rate deficit anomaly, relative to previous analyses, but the anomaly in the ratios of measured antineutrino spectra persists. We comment on upcoming experiments and their ability to probe the preferred region of the sterile-neutrino parameter space in the electron neutrino disappearance channel.
Comments:
7 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1909.09267 [pdf]
PRD(2020)·39 citations
06
[Submitted on 20 Sept 2019] (cross-list from hep-ph)
The decay $J / ψ \to γ ϕϕ$ : spin dependence of amplitude and angular distributions of photons with linear polarizations
A.A. Kozhevnikov🇷🇺
Based on the effective invariant amplitudes of the transitions $J / ψ \to γ X (J^{P})$ and $X (J^{P}) \to ϕϕ$ , the spin dependence of the $J / ψ \to γ X (J^{P}) \to γ ϕϕ$ decay amplitude is obtained in the case of the intermediate resonances $X$ with $J^{P} = 0^{\pm}, 1^{\pm}, 2^{\pm}$ . Angular distributions of photons with the definite linear polarizations relative to the plane spanned by the momentum of initial electron and the total momentum of the $ϕϕ$ pair in the reaction $e^{+} e^{-} \to J / ψ \to γ X (J^{P}) \to γ ϕϕ$ are calculated. It is shown that the sign of the asymmetry of the distributions of the photons polarized in the above plane and orthogonal to it correlates with the signature $P_{X} (- 1)^{J_{X}}$ of the $X$ resonance with given spin-parity $J_{X}^{P_{X}}$ so it may help to establish this quantum number in a way which does not depend on the specific model of the $X (J^{P}) \to ϕϕ$ amplitude.
Comments:
11 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1909.09311 [pdf]
EPJA(2019)·3 citations
07
[Submitted on 20 Sept 2019] (cross-list from hep-ph)
Flavor structures of charged fermions and massive neutrinos
Zhi-zhong Xing🇨🇳
Most of the free parameters in the Standard Model (SM) -- a quantum field theory which has successfully elucidated the behaviors of strong, weak and electromagnetic interactions of all the known fundamental particles, come from the lepton and quark flavors. The discovery of neutrino oscillations has proved that the SM is incomplete, at least in its lepton sector; and thus the door of opportunity is opened to exploring new physics beyond the SM and solving a number of flavor puzzles. In this review article we give an overview of important progress made in understanding the mass spectra, flavor mixing patterns, CP-violating effects and underlying flavor structures of charged leptons, neutrinos and quarks in the past twenty years. After introducing the standard pictures of fermion mass generation, flavor mixing and CP violation in the SM extended with the presence of massive Dirac or Majorana neutrinos, we briefly summarize current experimental knowledge about the flavor parameters of quarks and leptons. Various ways of describing flavor mixing and CP violation are discussed, the renormalization-group evolution of flavor parameters is illuminated, and the matter effects on neutrino oscillations are interpreted. Taking account of possible extra neutrino species, we propose a standard parametrization of the $6 \times 6$ flavor mixing matrix and comment on the phenomenological aspects of heavy, keV-scale and light sterile neutrinos. We pay particular attention to those novel and essentially model-independent ideas or approaches regarding how to determine the Yukawa textures of Dirac fermions and the effective mass matrix of Majorana neutrinos, including simple discrete and continuous flavor symmetries. An outlook to the future development in unravelling the mysteries of flavor structures is also given.
Comments:
227 pages, 36 figures, final version matching the published version in Physics Reports
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1909.09610 [pdf]
Phys.Rept.(2020)·338 citations

Affiliations

first authorsco-authorsvia INSPIRE

Light Nuclei Production in Au+Au Collisions at sNN​​ = 5-200 GeV from JAM model

Precision calculation of isospin-symmetry-breaking corrections to T=1/2 mirror decays using multi-reference charge-dependent density functional theory

Shell closure at N=34 and the 48Si nucleus

Nuclear chart in covariant density functional theory with dynamical correlations: From Oxygen to Tin

Reevaluating Reactor Antineutrino Anomalies with Updated Flux Predictions

The decay J/ψ→γϕϕ: spin dependence of amplitude and angular distributions of photons with linear polarizations

Flavor structures of charged fermions and massive neutrinos

Affiliations

Light Nuclei Production in Au+Au Collisions at $s_{NN}$ = 5-200 GeV from JAM model

Shell closure at $N = 34$ and the $^{48}$ Si nucleus

The decay $J / ψ \to γ ϕϕ$ : spin dependence of amplitude and angular distributions of photons with linear polarizations