Nuclear Theory·nucl-th

Thursday·May 17, 2018

9 papers—7 primary·2 cross-listed

01
[Submitted on 15 May 2018]
Electric dipole moment of light nuclei - 6Li, 7Li, 9Be, 11B, and 13C -
Nodoka Yamanaka🇫🇷
In this proceeding, we present the results of the theoretical evaluations of the electric dipole moment (EDM) of light nuclei, including the preliminary value for the 11B nucleus. From the data, we can infer an approximate counting rule, and predict the EDM of other light nuclei.
Comments:
6 pages, 2 figures, proceeding of the 13th conference on Low Energy Antiprotons Physics (LEAP2018), March 12-16, 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1805.05982 [pdf]
Hyperfine Interact.(2018)·6 citations
02
[Submitted on 15 May 2018]
Quantum Dynamics of Nuclear Slabs: Mean Field and Short-Range Correlations
Hossein Mahzoon (Michigan State U and Truman State U) · Pawel Danielewicz (Michigan State U) · Arnau Rios (U Surrey)
Computational difficulties aside, nonequilibrium Green's functions appear ideally suited for investigating the dynamics of central nuclear reactions. Many particles actively participate in those reactions. At the two energy extremes for the collisions, the limiting cases of the Green's function approach have been successful: the time-dependent Hartree-Fock theory at low energy and Boltzmann equation at high. The strategy for computational adaptation of the Green's function to central reactions is discussed. The strategy involves, in particular, incremental progression from one to three dimensions to develop and assess approximations, discarding of far-away function elements, use of effective interactions and preparation of initial states for the reactions through adiabatic switching. At this stage we concentrate on inclusion of correlations in one dimension, where relatively few approximations are needed, and we carry out reference calculations that can benchmark approximations needed for more dimensions. We switch on short-range interactions generating the correlations adiabatically in the Kadanoff-Baym equations to arrive at correlated ground states for uniform matter. As the energy of the correlated matter does not quite match the expectations for nuclear matter we add mean field to arrive at the match in energy. From there on, we move to finite systems. In switching on the correlations we observe emergence of extended tails in momentum distributions and evolution of single particle occupations away from 1 and 0.
Comments:
Contribution to Proc. Frontiers of Quantum and Mesoscopic Thermodynamics, 9-15 July 2017, Prague, Czech Republic, ed. Vaclav Spicka; 10 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1805.06030 [pdf]
Eur.Phys.J.ST(2019)·3 citations
03
[Submitted on 15 May 2018]
Large- $N_{c}$ Relationships Among Two-Derivative Pionless Effective Field Theory Couplings
Matthias R. Schindler🇺🇸 · Hersh Singh🇺🇸 · Roxanne P. Springer🇺🇸
We analyze two-derivative two-nucleon interactions in a combined pionless effective field theory and large- $N_{c}$ expansion. At leading order in the large- $N_{c}$ expansion, relationships among low-energy constants emerge. We find these to be consistent with experiment. However, it is critical to correctly address the subtraction-point dependence of the low-energy constants. These results provide additional confidence that the dual-expansion procedure is useful for analyzing low-energy few-body observables.
Comments:
33 pages, 5 figures, version accepted for publication
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1805.06056 [pdf]
PRC(2018)·19 citations
04
[Submitted on 16 May 2018]
Isoscalar neutron-proton pairing and SU(4)-symmetry breaking in Gamow-Teller transitions
K. Kaneko · Y. Sun · T. Mizusaki
The isoscalar neutron-proton pairing is thought to be important for nuclei with equal number of protons and neutrons but its manifestation in structure properties remains to be understood. We investigate the Gamow-Teller (GT) transitions for the f7/2-shell nuclei in large-scale shell-model calculations with the realistic Hamiltonian. We show that the isoscalar T=0, J=1+ neutron-proton pairing interaction plays a decisive role for the concentration of GT strengths at the first-excited 1+ state in 42Sc, and that the suppression of these strengths in 46V, 50Mn, and 54Co is mainly caused by the spin-orbit force supplemented by the quadrupole-quadrupole interaction. Based on the good reproduction of the charge-exchange reaction data, we further analyze the interplay between the isoscalar and isovector pairing correlations. We conclude that even for the most promising A=42 nuclei where the SU(4) isoscalar-isovector-pairing symmetry is less broken, the probability of forming an isoscalar neutron-proton pairing condensation is less than 60% as compared to the expectation at the SU(4)-symmetry limit.
Comments:
5 pages, 4 figures, accepted in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1805.06136 [pdf]
PRC(2018)·12 citations
05
[Submitted on 16 May 2018]
Multiple chiral doublets in four- $j$ shells particle rotor model: five possible chiral doublets in $_{60}^{136}$ Nd $_{76}$
Q. B. Chen🇩🇪 · B. F. Lv🇫🇷 · C. M. Petrache🇫🇷 · J. Meng🇨🇳
A particle rotor model, which couples nucleons in four single- $j$ shells to a triaxial rotor core, is developed to investigate the five pairs of nearly degenerate doublet bands recently reported in the even-even nucleus $^{136}$ Nd. The experimental energy spectra and available $B (M 1) / B (E 2)$ values are successfully reproduced. The angular momentum geometries of the valence nucleons and the core support the chiral rotation interpretations not only for the previously reported chiral doublet, but also for the other four candidates. Hence, $^{136}$ Nd is the first even-even candidate nucleus in which the multiple chiral doublets exist. Five pairs of chiral doublet bands in a single nucleus is also a new record in the study of nuclear chirality.
Comments:
15 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1805.06162 [pdf]
PLB(2018)·60 citations
06
[Submitted on 16 May 2018]
Heavy Quarkonium Dissociation by Thermal Gluons at Next-to-leading Order in the Quark-Gluon Plasma
Shile Chen🇨🇳 · Min He🇨🇳
Using the chromo-electric dipole coupling Hamiltonian from QCD multipole expansion, we derive the dissociation cross sections of heavy quarkonia by thermal gluons at next-to-leading order (NLO, also known as inelastic parton scattering dissociation) in the Quark-Gluon Plasma (QGP) in the framework of second order quantum mechanical perturbation theory. While suffering divergence (infrared and soft-collinear divergences) in vacuum, the cross sections thus derived become finite in the QGP as rendered by the finite thermal gluon masses. In contrast to the leading order (LO, also known as gluo-dissociation) counterparts rapidly dropping off with increasing incident gluon energy, the NLO cross sections exhibits finite value toward high energies because of new phase space being opened up. We then carry out a full calculation of the dissociation rates for various charmonia and bottomonia within a non-relativistic in-medium potential model. The NLO process is shown to dominate the dissociation rate toward high temperatures when the binding energies of heavy quarkonia become smaller relative to the Debye screening mass.
Comments:
11 pages, 6 figures; version accepted for publication in Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1805.06346 [pdf]
PLB(2018)·14 citations
07
[Submitted on 16 May 2018]
New Perspective on Hybrid Mesons
Shu-Sheng Xu🇨🇳 · Zhu-Fang Cui🇨🇳 · Lei Chang🇨🇳 · Joannis Papavassiliou🇪🇸 · Craig D. Roberts🇺🇸 · Hong-Shi Zong🇨🇳
It is thought that strong interactions within the Standard Model can generate bound-states in which non-Abelian gauge-bosons play a dual role, serving both as force and matter fields. In this context we introduce a novel approach to the hybrid-meson (valence-gluon+quark+antiquark) bound-state problem in relativistic quantum field theory. Exploiting the existence of strong two-body correlations in the gluon-quark, $q_{g} = [g q]$ , and gluon-antiquark, $q ˉ_{g} = [g q ˉ]$ channels, we argue that a sound description of hybrid properties can be obtained by solving a coupled-pair of effectively two-body equations; and, consequently, that hybrids may be viewed as highly-correlated $q_{g} q ˉ \leftrightarrow q q ˉ_{g}$ bound-states. Analogies may be drawn between this picture of hybrid structure and that of baryons, in which quark+quark (diquark) correlations play a key role. The potential of this formulation is illustrated by calculating the spectrum of light-quark isovector hybrid mesons.
Comments:
5 pages, 2 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1805.06430 [pdf]
EPJA(2019)·33 citations
08
[Submitted on 15 May 2018] (cross-list from astro-ph.HE)
Transport coefficients of leptons in superconducting neutron star cores
Peter Shternin🇷🇺
I consider the thermal conductivity and shear viscosity of leptons (electrons and muons) in the nucleon NS cores where protons are in the superconducting state. I restrict the consideration to the case of not too high temperatures $T ≲ 0.35 T_{c p}$ , where $T_{c p}$ is the critical temperature of the proton pairing. In this case, lepton collisions with protons can be neglected. Charged lepton collision frequencies are mainly determined by the transverse plasmon exchange and are mediated by the character of the transverse plasma screening. In our previous works [Shternin \& Yakovlev, Phys. Rev. D {\bf 75} 103004 (2007); {\bf 78} 063006 (2008)] the superconducting proton contribution to the transverse screening was considered in the Pippard limit $Δ ≪ ℏ q v_{F p}$ , where $Δ$ is the proton pairing gap, $v_{F p}$ is the proton Fermi velocity, and $ℏ q$ is the typical transferred momentum in collisions. However, for large critical temperatures (large $Δ$ ) and relatively small densities (small $q$ ) the Pippard limit may become invalid. In the present study I show that this is indeed the case and that the older calculations severely underestimated the screening in a certain range of the parameters appropriate to the neutron star cores. As a consequence, the kinetic coefficients at $T ≪ T_{c p}$ are found to be smaller than in previous calculations.
Comments:
18 pages, 11 figures, accepted for publication in PRD. In v.2 new figure 9 is added and BSK21 results are corrected
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1805.06000 [pdf]
PRD(2018)·16 citations
09
[Submitted on 16 May 2018] (cross-list from hep-ph)
Spectroscopy of the hidden-charm $[q c] [q ˉ c ˉ]$ and $[sc] [s ˉ c ˉ]$ tetraquarks
Muhammad Naeem Anwar🇨🇳 · Jacopo Ferretti🇨🇳 · Elena Santopinto🇮🇹
We calculate the spectrum of $q q ˉ c c ˉ$ and $s s ˉ c c ˉ$ tetraquarks, where $q$ , $s$ and $c$ stand for light ( $u, d$ ), strange and charm quarks, respectively, in a relativized diquark model, characterized by one-gluon-exchange (OGE) plus confining potential. In the diquark model, a $q q ˉ c c ˉ$ ( $s s ˉ c c ˉ$ ) tetraquark configuration is made up of a heavy-light diquark, $q c$ ( $sc$ ), and anti-diquark, $q ˉ c ˉ$ ( $s ˉ c ˉ$ ). According to our results, 13 charmonium-like observed states can be accommodated in the tetraquark picture, both in the hidden-charm ( $q q ˉ c c ˉ$ ) and hidden-charm hidden-strange ( $s s ˉ c c ˉ$ ) sectors.
Comments:
Discussions extended, references added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1805.06276 [pdf]
PRD(2018)·78 citations

Affiliations

first authorsco-authorsvia INSPIRE