Nuclear Theory·nucl-th

Tuesday·April 14, 2015

14 papers—5 primary·9 cross-listed

01
Many-body forces, isospin asymmetry and dense hyperonic matter
R.O. Gomes🇩🇪 · V. Dexheimer🇺🇸 · S. Schramm🇩🇪 · C.A.Z. Vascconcellos🇧🇷
The equation of state (EoS) of asymmetric nuclear matter at high densities is a key topic for the description of matter inside neutron stars. The determination of the properties of asymmetric nuclear matter, such as the symmetry energy ( $a_{sy m}$ ) and the slope of the symmetry energy ( $L_{0}$ ) at saturation density, has been exaustively studied in order to better constrain the nuclear matter EoS. However, differently from symmetric matter properties that are reasonably constrained, the symmetry energy and its slope still large uncertainties in their experimental values. Regarding this subject, some studies point towards small values of the slope of the symmetry energy, while others suggest rather higher values. Such a lack of agreement raised a certain debate in the scientific community. In this paper, we aim to analyse the role of these properties on the behavior of asymmetric hyperonic matter. Using the formalism presented in Ref. (R.O. Gomes et al 2014}, which considers many-body forces contributions in the meson-baryon coupling, we calculate the EoS of asymmetric hyperonic matter and apply it to describe hyperonic matter and hyperon stars.
nucl-thastro-ph.SR0 citations
02
Condition for the burning of hadronic stars into quark stars
A. Drago🇮🇹 · G. Pagliara🇮🇹
We will review the approach used for studying the conversion of a hadronic star into a quark star based on the assumption of a infinitely thin combustion zone and we will discuss why, in this scheme, the combustion stops before the whole hadronic star is converted.
nucl-thastro-ph.SR4 citations
03
R-Matrix description of particle energy spectra produced by low-energy T+T reactions
C.R. Brune · J.A. Caggiano · D.B. Sayre · A.D. Bacher · G.M. Hale · M.W. Paris
An R-matrix model for three-body final states is presented and applied to a recent measurement of the neutron energy spectrum from the T+T->2n+alpha reaction. The calculation includes the n-alpha and n-n interactions in the final state, angular momentum conservation, antisymmetrization, and the interference between different channels. A good fit to the measured spectrum is obtained, where clear evidence for the 5He ground state is observed. The model is also used to predict the alpha-particle spectrum from T+T as well as particle spectra from 3He+3He. The R-matrix approach presented here is very general, and can be adapted to a wide variety of problems with three-body final states.
nucl-thnucl-exPRC(2015)·17 citations
04
Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force
K. Nomura🇫🇷 · R. Rodríguez-Guzmán🇰🇼 · L. M. Robledo🇪🇸
Collective quadrupole and octupole states are described in a series of Sm and Gd isotopes within the framework of the interacting boson model (IBM), whose Hamiltonian parameters are deduced from mean field calculations with the Gogny energy density functional. The link between both frameworks is the ( $β_{2} β_{3}$ ) potential energy surface computed within the Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The diagonalization of the IBM Hamiltonian provides excitation energies and transition strengths of an assorted set of states including both positive and negative parity states. The resultant spectroscopic properties are compared with the available experimental data and also with the results of the configuration mixing calculations with the Gogny force within the generator coordinate method (GCM). The structure of excited $0^{+}$ states and its connection with double octupole phonons is also addressed. The model is shown to describe the empirical trend of the low-energy quadrupole and octupole collective structure fairly well, and turns out to be consistent with GCM results obtained with the Gogny force.
nucl-thPRC(2015)·61 citations
05
Properties of nuclei in the nobelium region studied within the covariant, Skyrme, and Gogny energy density functionals
J. Dobaczewski · A.V. Afanasjev · M. Bender · L.M. Robledo · Yue Shi
We calculate properties of the ground and excited states of nuclei in the nobelium region for proton and neutron numbers of 92 <= Z <= 104 and 144 <= N <= 156, respectively. We use three different energy-density-functional (EDF) approaches, based on covariant, Skyrme, and Gogny functionals, each within two different parameter sets. A comparative analysis of the results obtained for odd-even mass staggerings, quasiparticle spectra, and moments of inertia allows us to identify single-particle and shell effects that are characteristic to these different models and to illustrate possible systematic uncertainties related to using the EDF modelling
nucl-thNPA(2015)·74 citations
06
Solution of the Hyperon Puzzle within a Relativistic Mean-Field Model
K.A. Maslov🇷🇺 · E.E. Kolomeitsev🇸🇰 · D.N. Voskresensky🇷🇺
The equation of state of cold baryonic matter is studied within a relativistic mean-field model with hadron masses and coupling constants depending on the scalar field. All hadron masses undergo a universal scaling, whereas the coupling constants are scaled differently. The appearance of hyperons in dense neutron star interiors is accounted for, however the equation of state remains sufficiently stiff if a reduction of the $ϕ$ meson mass is included. Our equation of state matches well the constraints known from analyses of the astrophysical data and the particle production in heavy-ion collisions.
↳ astro-ph.HEnucl-thPLB(2015)·108 citations
07
Perturbative study of the QCD phase diagram for heavy quarks at nonzero chemical potential
Urko Reinosa🇫🇷 · Julien Serreau🇫🇷 · Matthieu Tissier🇫🇷
We investigate the phase diagram of QCD with heavy quarks at finite temperature and chemical potential in the context of background field methods. In particular, we use a massive extension of the Landau-DeWitt gauge which is motivated by previous studies of the deconfinement phase transition in pure Yang-Mills theories. We show that a simple one-loop calculation is able to capture the richness of the phase diagram in the heavy quark region, both at real and imaginary chemical potential. Moreover, dimensionless ratios of quantities directly measurable in numerical simulations are in good agreement with lattice results.
↳ hep-thhep-lathep-phnucl-thPRD(2015)·67 citations
08
Evading the sign problem in the mean-field approximation through Lefschetz-thimble path integral
Yuya Tanizaki🇯🇵 · Hiromichi Nishimura🇩🇪 · Kouji Kashiwa🇯🇵
The fermion sign problem appearing in the mean-field approximation is considered, and the systematic computational scheme of the free energy is devised by using the Lefschetz-thimble method. We show that the Lefschetz-thimble method respects the reflection symmetry, which makes physical quantities manifestly real at any order of approximations using complex saddle points. The formula is demonstrated through the Airy integral as an example, and its application to the Polyakov-loop effective model of dense QCD is discussed in detail.
↳ hep-thcond-mat.str-elhep-lathep-ph+1PRD(2015)·62 citations
09
Reduced quasifission competition in fusion reactions forming neutron-rich heavy elements
K. Hammerton · Z. Kohley · D. J. Hinde · M. Dasgupta · A. Wakhle · E. Williams · V. E. Oberacker · A. S. Umar · I. P. Carter · K. J. Cook · J. Greene · D. Y. Jeung and 6 other authors
Measurements of mass-angle distributions (MADs) for Cr + W reactions, providing a wide range in the neutron-to-proton ratio of the compound system, (N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be determined in a model-independent way. Previous experimental and theoretical studies had produced conflicting conclusions. The experimental MADs reveal an increase in contact time and mass evolution of the quasifission fragments with increasing (N/Z)CN, which is indicative of an increase in the fusion probability. The experimental results are in agreement with microscopic time-dependent Hartree-Fock calculations of the quasifission process. The experimental and theoretical results favor the use of the most neutron-rich projectiles and targets for the production of heavy and superheavy nuclei.
↳ nucl-exnucl-thPRC(2015)·61 citations
10
Bulk viscosity in a plasma of Gribov-Zwanziger gluons
Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱 · Nan Su🇩🇪 · Konrad Tywoniuk🇪🇸
We investigate dynamic properties of a plasma whose constituents are confining gluons resulting from the Gribov quantization. In a static formulation, this system reproduces qualitatively the pure-glue equation of state and thereby encodes crucial features of the phase transition. The dynamic description proposed in this work allows us to study non-equilibrium transport phenomena with the inclusion of confinement effects. In particular, we determine the non-equilibrium behaviour of the interaction measure (trace anomaly) and find the form of the bulk viscosity coefficient. The latter may be used in phenomenological applications to heavy-ion collisions.
↳ hep-phhep-lathep-thnucl-thActa Phys.Polon.B(2016)·40 citations
11
Chiral vortical wave and induced flavor charge transport in a rotating quark-gluon plasma
Yin Jiang🇺🇸 · Xu-Guang Huang🇨🇳 · Jinfeng Liao🇺🇸
We show the existence of a new gapless collective excitation in a rotating fluid system with chiral fermions, named as the Chiral Vortical Wave (CVW). The CVW has its microscopic origin at the quantum anomaly and macroscopically arises from interplay between vector and axial charge fluctuations induced by vortical effects. The wave equation is obtained both from hydrodynamic current equations and from chiral kinetic theory and its solutions show nontrivial CVW-induced charge transport from different initial conditions. Using the rotating quark-gluon plasma in heavy ion collisions as a concrete example, we show the formation of induced flavor quadrupole in QGP and estimate the elliptic flow splitting effect for Lambda baryons that may be experimentally measured.
↳ hep-phhep-thnucl-thPRD(2015)·116 citations
12
A possibility of quark spin polarized phase in high density quark matter
Y. Tsue (Kochi Univ., Japan)🇵🇹 · J. da Providencia (Univ. de Coimbra, Portugal)🇵🇹 · C. Providencia (Univ. de Coimbra, Portugal)🇵🇹 · M. Yamamura (Kansai Univ., Japan)🇯🇵 · H. Bohr (Danish Technical Univ., Denmark)🇩🇰
It is shown that the quark spin polarization may occur for each quark flavor by the use of the Nambu-Jona-Lasinio model with a tensor-type four-point interaction between quarks, while the two-flavor color superconducting phase in two-flavor case may be realized at high density quark matter.
↳ hep-phnucl-thActa Astron.Sin.Suppl.(2015)·0 citations
13
Dispersive calculation of complex Regge trajectories for the lightest $f_{2}$ resonances
J.A. Carrasco🇪🇸 · J. Nebreda🇪🇸 · J.R. Pelaez🇪🇸 · A.P. Szczepaniak🇺🇸
We apply a recently developed dispersive formalism to calculate the Regge trajectories of the $f_{2} (1270)$ and $f_{2}^{'} (1525)$ mesons. Trajectories are calculated, not fitted to a family of resonances. Assuming that these spin-2 resonances can be treated in the elastic approximation the only input are the pole position and residue of the resonances. In both cases, the predicted Regge trajectories are almost real and linear, with slopes in agreement with the universal value of order 1 GeV $^{- 2}$ .
↳ hep-phnucl-thPLB(2015)·16 citations
14
Sensitivity of multiplicity fluctuations to freeze-out conditions in heavy ion collisions
Paolo Alba🇮🇹 · Rene Bellwied🇺🇸 · Marcus Bluhm🇺🇸 · Valentina Mantovani Sarti🇮🇹 · Marlene Nahrgang🇺🇸 · Claudia Ratti🇺🇸
We study the sensitivity of the higher-order moments of produced particle multiplicity distributions to the chemical freeze-out parameters in relativistic heavy ion collisions using the Hadron Resonance Gas (HRG) model. We compare the obtained sensitivity level to the one extracted from the ratios of particle yields. We find that, for certain final state hadrons, the fluctuation measurements add significant information to the determination of the hadro-chemical freeze-out properties of the deconfined phase of matter obtained at RHIC and the LHC.
↳ hep-phnucl-thPRC(2015)·50 citations

Affiliations

first authorsco-authorsvia INSPIRE