Nuclear Theory·nucl-th

Thursday·August 20, 2015

12 papers—9 primary·3 cross-listed

01
Using spectator distributions to measure the initial geometry fluctuation
Md Nasim🇺🇸
A study of eccentricity ( $ε_{n}$ ) fluctuations and its possible impact on final state momentum anisotropy ( $v_{n}$ ) for symmetric collisions are presented in the framework of Glauber model. Effect of fluctuations of nucleon's position on the initial geometry has been studied using a new method, where the difference between oppositely moving spectators is taken as a measurement of eccentricity fluctuations. This study shows that higher harmonics ( $n$ =3, 4 and 5) of eccentricity are less sensitive to fluctuations in transverse plane compared to the 2 $^{n d}$ harmonic. Position fluctuations in transverse plane will increase $ε_{2}$ and hence possibly $v_{2}$ for the most central nucleus-nucleus collisions. For semi-central and peripheral collisions, the fluctuations have opposite effect, it deceases the eccentricity $ε_{2}$ . The fluctuation of initial geometry can be studied in collider experiments by studying the spectator distribution on the both sides of the beam.
nucl-thhep-phnucl-exIJMPE(2015)·0 citations
02
Impact of pion dynamics on nuclear shell structure
Elena Litvinova
Spin-isospin response in exotic nuclear systems is investigated. It is found that in some nuclei excitations with pionic quantum numbers (0-, 1+, 2-, ...) appear at very low energies with large transition probabilities, which is an indication of the vicinity of the onset of pion condensation. As an example, 2- components of the spin-dipole resonance in 78-Ni and 132-Sn are considered. The existence of such modes points out to the necessity of taking into account their coupling to other elementary modes of excitation, e.g. single-quasiparticle ones. This coupling is introduced in the theory for the first time. Thereby, pion-exchange contribution to the nucleon-nucleon interaction is included in the relativistic framework beyond the Hartree-Fock approximation. Namely, classes of Feynman diagrams are selected according to their significance for nuclear spectroscopic characteristics, such as single-particle energies and strength functions, and included into the nucleonic self-energy in all orders of meson-exchange. As an illustration, the impact of these new contributions on the single-particle energies of 100-Sn is discussed.
nucl-thAIP Conf.Proc.(2015)·1 citation
03
Anisotropic hydrodynamics for mixture of quark and gluon fluids
Wojciech Florkowski🇵🇱 · Ewa Maksymiuk🇵🇱 · Radoslaw Ryblewski🇵🇱 · Leonardo Tinti🇵🇱
A system of equations for anisotropic hydrodynamics is derived that describes a mixture of anisotropic quark and gluon fluids. The consistent treatment of the zeroth, first and second moments of the kinetic equations allows us to construct a new framework with more general forms of the anisotropic phase-space distribution functions than those used before. In this way, the main difficiencies of the previous formulations of anisotropic hydrodynamics for mixtures have been overcome and the good agreement with the exact kinetic-theory results is obtained.
nucl-thPRC(2015)·29 citations
04
Limiting temperature of pion gas with the van der Waals equation of state
R. V. Poberezhnyuk · V. Vovchenko · D. V. Anchishkin · M. I. Gorenstein
The grand canonical ensemble formulation of the van der Waals equation of state that includes the effects of Bose statistics is applied to an equilibrium system of interacting pions. If the attractive interaction between pions is large enough, a limiting temperature $T_{0}$ emerges, i.e., no thermodynamical equilibrium is possible at $T > T_{0}$ . The system pressure $p$ , particle number density $n$ , and energy density $ε$ remain finite at $T = T_{0}$ , whereas for $T$ near $T_{0}$ both the specific heat $C = d ε / d T$ and the scaled variance of particle number fluctuations $ω [N]$ are proportional to $(T_{0} - T)^{- 1/2}$ and, thus, go to infinity at $T \to T_{0}$ . The limiting temperature corresponds also to the softest point of the equation of state, i.e., the speed of sound squared $c_{s}^{2} = d p / d ε$ goes to zero as $(T_{0} - T)^{1/2}$ . Very similar thermodynamical behavior takes place in the Hagedorn model for the special choice of a power, namely $m^{- 4}$ , in the pre-exponential factor of the mass spectrum $ρ (m)$ .
nucl-thJ.Phys.G(2016)·9 citations
05
Symmetry Remnants in the Face of Competing Interactions in Nuclei
A. Leviatan · M. Macek
Detailed description of nuclei necessitates model Hamiltonians which break most dynamical symmetries. Nevertheless, generalized notions of partial and quasi dynamical symmetries may still be applicable to selected subsets of states, amidst a complicated environment of other states. We examine such scenarios in the context of nuclear shape-phase transitions.
nucl-thnlin.CDquant-phAIP Conf.Proc.(2015)·0 citations
06
Quasifission dynamics in TDHF
A.S. Umar · V.E. Oberacker · C. Simenel
For light and medium mass systems the capture cross-section may be considered to be the same as that for complete fusion, whereas for heavy systems leading to superheavy formations the evaporation residue cross-section is dramatically reduced due to the quasifission (QF) and fusion-fission processes thus making the capture cross-section to be essentially the sum of these two cross-sections, with QF occurring at a much shorter time-scale. Consequently, quasifission is the primary reaction mechanism that limits the formation of superheavy nuclei. Within the last few years the time-dependent Hartree-Fock (TDHF) approach has been utilized for studying the dynamics of quasifission. The study of quasifission is showing a great promise to provide insight based on very favorable comparisons with experimental data. In this article we will focus on the TDHF calculations of quasifission observables for the $^{48}$ Ca+ $^{249}$ Bk system.
nucl-thEPJ Web Conf.(2016)·1 citation
07
Entanglement in the states of the Two-Rotor-Model
Fabrizio Palumbo
The eigenfunctions of the Two-Rotors Model are superpositions of states corresponding to precessions of the rotors around two orthogonal axes. In Nuclear Physics such an entanglement has not been directly confirmed. We discuss how it might be observed and compare with the application of the TRM to single domain nanoparticles. In the latter case, in addition to the present indirect evidence there is the possibility of direct observation in experiments at temperatures of the order of 1 K.
nucl-thPRC(2016)·4 citations
08
Modelling Hybrid Stars in Quark-Hadron Approaches
S. Schramm🇩🇪 · V. Dexheimer🇺🇸 · R. Negreiros🇧🇷
The density in the core of neutron stars can reach values of about 5 to 10 times nuclear matter saturation density. It is, therefore, a natural assumption that hadrons may have dissolved into quarks under such conditions, forming a hybrid star. This star will have an outer region of hadronic matter and a core of quark matter or even a mixed state of hadrons and quarks. In order to investigate such phases, we discuss different model approaches that can be used in the study of compact stars as well as being applicable to a wider range of temperatures and densities. One major model ingredient, the role of quark interactions in the stability of massive hybrid stars is discussed. In this context, possible conflicts with lattice QCD simulations are investigated.
nucl-thEPJA(2016)·24 citations
09
Strangeness in nuclei and neutron stars: a challenging puzzle
Diego Lonardoni🇺🇸 · Alessandro Lovato🇺🇸 · Stefano Gandolfi🇺🇸 · Francesco Pederiva🇮🇹
The prediction of neutron stars properties is strictly connected to the employed nuclear interactions. The appearance of hyperons in the inner core of the star is strongly dependent on the details of the underlying hypernuclear force. We summarize our recent quantum Monte Carlo results on the development of realistic two- and three-body hyperon-nucleon interactions based on the available experimental data for light- and medium-heavy hypernuclei.
nucl-thEPJ Web Conf.(2016)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE