Nuclear Theory·nucl-th

Wednesday·January 13, 2016

8 papers—5 primary·3 cross-listed

01
Symmetries and deformations in the spherical shell model
Piet Van Isacker🇫🇷 · Stuart Pittel🇺🇸
We discuss symmetries of the spherical shell model that make contact with the geometric collective model of Bohr and Mottelson. The most celebrated symmetry of this kind is SU(3), which is the basis of Elliott's model of rotation. It corresponds to a deformed mean field induced by a quadrupole interaction in a single major oscillator shell N and can be generalized to include several major shells. As such, Elliott's SU(3) model establishes the link between the spherical shell model and the (quadrupole component of the) geometric collective model. We introduce the analogue symmetry induced by an octupole interaction in two major oscillator shells N-1 and N, leading to an octupole-deformed solution of the spherical shell model. We show that in the limit of large oscillator shells (large N) the algebraic octupole interaction tends to that of the geometric collective model.
nucl-thPhys.Scripta(2016)·22 citations
02
Influence of the weakly interacting light U boson on the properties of massive PNS
Bin Hong · Huan-Yu Jia · Xia Zhou · Xue-Ling Mu
Considering the octet baryons in relativistic mean field theory and selecting entropy per baryon S=1, we calculate and discuss the influence of U boson on the equation of state, mass-radius, moment of inertia and gravitational redshift of massive protoneutron star (PNS). The effective coupling constant $g_{U}$ of U bosons and nucleons is selected from 0GeV $^{- 2}$ to 70GeV $^{- 2}$ . The results point that U bosons will stiffen the equation of state (EOS). The influence of U bosons on the pressure is more obvious at low density than high density, while, the influence of U bosons on the energy density is more obvious at high density than low density. The U bosons play a significant role in increasing the maximum mass and radius of PNS. When the value of $g_{U}$ changes from 0GeV $^{- 2}$ to 70GeV $^{- 2}$ , the maximum mass of massive PNS increases from 2.11 $M_{⊙}$ to 2.58 $M_{⊙}$ , and the radius of PNS corresponding PSR J0348+0432 increases from 13.71 km to 24.35 km. The U bosons will increase the moment of inertia and decrease the gravitational redshift of PNS. For PNS of the massive PSR J0348+0432, the radius and moment of inertia vary directly with $g_{U}$ , the gravitational redshift vary inversely with $g_{U}$ approximately.
nucl-thastro-ph.HECPC(2016)·2 citations
03
On the emission of the fast $δ -$ electrons during nuclear $β^{-}$ -decay in few-electron atoms
Alexei M. Frolov
We discuss a possibility to observe fast secondary electrons ( $δ -$ electrons) during nuclear $β^{-}$ -decay in few-electron atoms and ions. Formulas for the corresponding probabilities and explicit expression for the energy spectrum of $δ -$ electrons are derived in the closed analytical forms.
nucl-thphysics.atom-phEPL(2016)·0 citations
04
Thermal evolution of hybrid stars within the framework of a nonlocal Nambu--Jona-Lasinio model
S. M. de Carvalho🇧🇷 · R. Negreiros🇧🇷 · M. Orsaria🇦🇷 · G. A. Contrera🇦🇷 · F. Weber🇺🇸 · W. Spinella🇺🇸
We study the thermal evolution of neutron stars containing deconfined quark matter in their core. Such objects are generally referred to as quark-hybrid stars. The confined hadronic matter in their core is described in the framework of non-linear relativistic nuclear field theory. For the quark phase we use a non-local extension of the SU(3) Nambu Jona-Lasinio model with vector interactions. The Gibbs condition is used to model phase equilibrium between confined hadronic matter and deconfined quark matter. Our study indicates that high-mass neutron stars may contain between 35 and 40 % deconfined quark-hybrid matter in their cores. Neutron stars with canonical masses of around $1.4 M_{⊙}$ would not contain deconfined quark matter. The central proton fractions of the stars are found to be high, enabling them to cool rapidly. Very good agreement with the temperature evolution established for the neutron star in Cassiopeia A (Cas A) is obtained for one of our models (based on the popular NL3 nuclear parametrization), if the protons in the core of our stellar models are strongly paired, the repulsion among the quarks is mildly repulsive, and the mass of Cas A has a canonical value of $1.4 M_{⊙}$ .
nucl-thastro-ph.HEhep-phPRC(2015)·27 citations
05
Partial wave decomposition of finite-range effective tensor interaction
D. Davesne🇫🇷 · P. Becker🇫🇷 · A. Pastore🇬🇧 · J. Navarro🇪🇸
We perform a detailed analysis of the properties of the finite-range tensor term associated with the Gogny and M3Y effective interactions. In particular, by using a partial wave decomposition of the equation of state of symmetric nuclear matter, we show how we can extract their tensor parameters directly from microscopic results based on bare nucleon-nucleon interactions. Furthermore, we show that the zero-range limit of both finite-range interactions has the form of the N3LO Skyrme pseudo-potential, which thus constitutes a reliable approximation in the density range relevant for finite nuclei. Finally, we use Brueckner-Hartree-Fock results to fix the tensor parameters for the three effective interactions.
nucl-thPRC(2016)·6 citations
06
The hidden-charm pentaquark and tetraquark states
Hua-Xing Chen🇨🇳 · Wei Chen🇨🇦 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳
In the past decade many charmonium-like states were observed experimentally. Especially those charged charmonium-like $Z_{c}$ states and bottomonium-like $Z_{b}$ states can not be accommodated within the naive quark model. These charged $Z_{c}$ states are good candidates of either the hidden-charm tetraquark states or molecules composed of a pair of charmed mesons. Recently, the LHCb Collaboration discovered two hidden-charm pentaquark states, which are also beyond the quark model. In this work, we review the current experimental progress and investigate various theoretical interpretations of these candidates of the multiquark states. We list the puzzles and theoretical challenges of these models when confronted with the experimental data. We also discuss possible future measurements which may distinguish the theoretical schemes on the underlying structures of the hidden-charm multiquark states.
↳ hep-phhep-exhep-latnucl-ex+1Phys.Rept.(2016)·1460 citations
07
Holographic Nambu Jona-Lasinio Interactions
Nick Evans🇬🇧 · Keun-Young Kim🇰🇷
NJL interactions are introduced into the D3/ probe D7 system using Witten's double trace operator prescription which includes the operator as a classical term in the effective potential. In the supersymmetric system they do not induce chiral symmetry breaking which we attribute to the flat effective potential with quark mass in the supersymmetric theory. If additional supersymmetry breaking is introduced then standard NJL behaviour is realized. In examples where chiral symmetry breaking is not preferred such as with a B field plus an IR cut off chiral condensation is triggered by the NJL interaction at a second order transition after a finite critical coupling. If the model already contains chiral symmetry breaking, for example in the B field case with no IR cut off, then the NJL interaction enhances the quark mass at all values of the NJL coupling. We also consider the system at finite temperature: the temperature discourages condensation but when combined with a magnetic field we find regions of parameter space where the NJL interaction triggers a first order chiral transition above a critical coupling.
↳ hep-thnucl-thPRD(2016)·18 citations
08
Nuclear collisions at the Future Circular Collider
N. Armesto🇪🇸 · A. Dainese🇮🇹 · D. d'Enterria🇨🇭 · S. Masciocchi🇩🇪 · C. Roland🇺🇸 · C.A. Salgado🇪🇸 · M. van Leeuwen🇳🇱 · U.A. Wiedemann🇨🇭
The Future Circular Collider is a new proposed collider at CERN with centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at assessing its physics potential and technical feasibility. Here we focus on updates in physics opportunities accessible in pA and AA collisions not covered in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon saturation studies, novel hard probes of QCD matter, and photon-induced collisions.
↳ hep-phhep-exnucl-exnucl-thNPA(2016)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE