Nuclear Theory·nucl-th

Thursday·July 13, 2017

9 papers—4 primary·5 cross-listed

01
[Submitted on 12 Jul 2017]
Strongly screening electron capture rates of chromium isotopes in presupernova
Jing-Jing Liu · Qiu-He Peng · Liang-Huan Hao · Xiao-Ping Kang · Dong-Mei Liu
Taking into account the effect of electron screening on the electron energy and electron capture threshold energy, by using the method of Shell-Model Monte Carlo and Random Phase Approximation theory, we investigate the strong electron screening capture rates of chromium isotopes according to the linear response theory screening model. The strong screening rates can decrease by about 40.43\% (e.g., for $^{60}$ Cr at $T_{9} = 3.44, Y_{e} = 0.43$ ). Our conclusions may be helpful to the researches of supernova explosion and numerical simulation.
Comments:
9 pages, 2 figures,Accepted for publication in Astronomy and Astrophysics (RAA)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.03504 [pdf]
Res.Astron.Astrophys.(2017)·19 citations
02
[Submitted on 12 Jul 2017]
Multiple multi-orbit pairing algebras in shell model and interacting boson models
V.K.B. Kota
In nuclei with valence nucleons are say identical nucleons and say these nucleons occupy several- $j$ orbits, then it is possible to consider pair creation operator $S_{+}$ to be a sum of the single- $j$ shell pair creation operators $S_{+} (j)$ with arbitrary phases, $S_{+} = \sum_{j} α_{j} S_{+} (j); α_{j} = \pm 1$ . In this situation, it is possible to define multi-orbit or generalized seniority that corresponds to the quasi-spin $S U (2)$ algebra generated by $S_{+}$ , $S_{-} = (S_{+})^{†}$ and $S_{0} = (n^- Ω) /2$ operators; $n^$ is number operator and $Ω = [\sum_{j} (2 j + 1)] /2$ . There are now multiple pairing quasi-spin $S U (2)$ algebras. Also, the $α_{j}$ 's and the generators of the corresponding generalized seniority generating sympletic algebras $S p (2Ω)$ in $U (2Ω) \supset S p (2Ω)$ have one-to-one correspondence. Using these, derived are the special seniority selection rules for electromagnetic transitions. A particular choice for $α_{j}$ 's as advocated by Arvieu and Moszkowski (AM) in the past gives pairing Hamiltonians having maximum correlation with well known effective interactions. The various results derived for identical fermion systems are shown to extend to identical boson systems with the bosons occupying several- $ℓ$ orbits as for example in $s d$ , $s p$ , $s d g$ and $s d p f$ IBM's. The quasi-spin algebra here is $S U (1, 1)$ and the generalized seniority quantum number is generated by $S O (2Ω)$ in $U (2Ω) \supset S O (2Ω)$ . The different $S O (2Ω)$ algebras here will be important in the study of quantum phase transitions and order-chaos transitions in nuclei.
Comments:
25 pages, 3 figure
Subjects:
Nuclear Theory (nucl-th); Mathematical Physics (math-ph); math.MP (math.MP)
arXiv:
1707.03552 [pdf]
Bulg.J.Phys.(2017)·4 citations
03
[Submitted on 12 Jul 2017]
Prolate over oblate dominance in deformed nuclei as a consequence of the SU(3) symmetry and the Pauli principle
Dennis Bonatsos
We show that the dominance of prolate over oblate shapes in even-even deformed nuclei can be derived from the SU(3) symmetry and the Pauli principle.
Comments:
2 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.03763 [pdf]
EPJA(2017)·41 citations
04
[Submitted on 12 Jul 2017]
TMDs of Spin-one Targets: Formalism and Covariant Calculations
Yu Ninomiya🇯🇵 · Wolfgang Bentz🇯🇵 · Ian C. Cloët🇺🇸
We present a covariant formulation and model calculations of transverse momentum-dependent quark distribution functions (TMDs) for spin-one hadrons. Emphasis is placed on a description of these 3-dimensional distribution functions which is independent of any constraints on the spin quantization axis. We apply our covariant spin description to all nine leading-twist time-reversal even $ρ$ meson TMDs in the framework provided by the Nambu--Jona-Lasinio model, incorporating important aspects of quark confinement via the infrared cut-off in the proper-time regularization scheme. In particular, the behavior of the 3-dimensional TMDs in a tensor polarized spin-one hadron are illustrated. Sum rules and positivity constraints are discussed in detail. Results of particular interest include the finding that the tensor polarized TMDs -- associated with spin-one hadrons -- are very sensitive to quark orbital angular momentum, and that the TMDs associated with the quark operator $γ^{+} γ_{T} γ_{5}$ would vanish were it not for dynamical chiral symmetry breaking. In addition, we find that 44% of the $ρ$ meson's spin is carried by the orbital angular momentum of the quarks, and that the magnitude of the tensor polarized quark distribution function is about 30% of the unpolarized quark distribution. A qualitative comparison between our results for the tensor structure of a quark-antiquark bound state is made to previous experimental and theoretical results for the two-nucleon (deuteron) bound state.
Comments:
16 pages, 9 figures (updated to agree with journal version -- some changes in notation)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1707.03787 [pdf]
PRC(2017)·50 citations

Affiliations

first authorsco-authorsvia INSPIRE

Strongly screening electron capture rates of chromium isotopes in presupernova

Multiple multi-orbit pairing algebras in shell model and interacting boson models

Prolate over oblate dominance in deformed nuclei as a consequence of the SU(3) symmetry and the Pauli principle

TMDs of Spin-one Targets: Formalism and Covariant Calculations

Affiliations