Nuclear Theory·nucl-th

Wednesday·July 20, 2016

9 papers—2 primary·7 cross-listed

01
Nuclear constraints on gravitational waves from deformed pulsars
Plamen G. Krastev🇺🇸 · Bao-An Li🇺🇸
The recent direct detection of gravitational waves (GWs) from binary black hole mergers (2016, Phys. Rev. Lett. 116, no. 6, 061102; no. 24, 241103) opens up an entirely new non-electromagnetic window into the Universe making it possible to probe physics that has been hidden or dark to electromagnetic observations. In addition to cataclysmic events involving black holes, GWs can be triggered by physical processes and systems involving neutron stars. Properties of neutron stars are largely determined by the equation of state (EOS) of neutron-rich matter, which is the major ingredient in calculating the stellar structure and properties of related phenomena, such as gravitational wave emission from elliptically deformed pulsars and neutron star binaries. Although the EOS of neutron-rich matter is still rather uncertain mainly due to the poorly known density dependence of nuclear symmetry energy at high densities, significant progress has been made recently in constraining the symmetry energy using data from terrestrial nuclear laboratories. These constraints could provide useful information on the limits of GWs expected from neutron stars. Here after briefly reviewing our previous work on constraining gravitational radiation from elliptically deformed pulsars with terrestrial nuclear laboratory data in light of the recent gravitational wave detection, we estimate the maximum gravitational wave strain amplitude, using an optimistic value for the breaking strain of the neutron star crust, for 15 pulsars at distances 0.16 kpc to 0.91 kpc from Earth, and find it to be in the range of $\sim [0.2 - 31.1] \times 1 0^{- 24}$ , depending on the details of the EOS used to compute the neutron star properties. Implications are discussed.
nucl-thastro-ph.HEastro-ph.SRnucl-ex2 citations
02
Prediction for a four-neutron resonance
A. M. Shirokov · G. Papadimitriou · A. I. Mazur · I. A. Mazur · R. Roth · J. P. Vary
We utilize various {\em ab initio} approaches to search for a low-lying resonance in the four-neutron ( $4 n$ ) system using the JISP16 realistic $N N$ interaction. Our most accurate prediction is obtained using a $J$ -matrix extension of the No-Core Shell Model and suggests a $4 n$ resonant state at an energy near $E_{r} = 0.8$ MeV with a width of approximately $Γ = 1.4$ MeV.
nucl-thnucl-exPRL(2016)·91 citations
03
Theory of neutrino emission from nucleon-hyperon matter in neutron stars: Angular integrals
A. D. Kaminker🇷🇺 · D. G. Yakovlev🇷🇺 · P. Haensel🇵🇱
Investigations of thermal evolution of neutron stars with hyperon cores require neutrino emissivities for many neutrino reactions involving strongly degenerate particles (nucleons, hyperons, electrons, muons). We calculate the angular integrals $I_{n}$ (over orientations of momenta of $n$ degenerate particles) for major neutrino reactions with $n$ =3, 4, 5 at all possible combinations of particle Fermi momenta. The integrals $I_{n}$ are necessary ingredients for constructing a uniform database of neutrino emissivities in dense nucleon-hyperon matter. The results can also be used in many problems of physical kinetics of strongly degenerate systems.
↳ astro-ph.HEastro-ph.SRnucl-thAstrophys.Space Sci.(2016)·18 citations
04
Holographic heavy ion collisions with baryon charge
Jorge Casalderrey-Solana🇬🇧 · David Mateos🇪🇸 · Wilke van der Schee🇺🇸 · Miquel Triana🇪🇸
We numerically simulate collisions of charged shockwaves in Einstein-Maxwell theory in anti-de Sitter space as a toy model of heavy ion collisions with non-zero baryon charge. The stress tensor and the baryon current become well described by charged hydrodynamics at roughly the same time. The effect of the charge density on generic observables is typically no larger than 15\%. %The rapidity profile of the charge is wider than the profile of the local energy density. We find significant stopping of the baryon charge and compare our results with those in heavy ion collision experiments.
↳ hep-thnucl-thJHEP(2016)·40 citations
05
Production of the entire range of r-process nuclides by black hole accretion disc outflows from neutron star mergers
Meng-Ru Wu · Rodrigo Fernández · Gabriel Martínez-Pinedo · Brian D. Metzger
We consider $r$ -process nucleosynthesis in outflows from black hole accretion discs formed in double neutron star and neutron star -- black hole mergers. These outflows, powered by angular momentum transport processes and nuclear recombination, represent an important -- and in some cases dominant -- contribution to the total mass ejected by the merger. Here we calculate the nucleosynthesis yields from disc outflows using thermodynamic trajectories from hydrodynamic simulations, coupled to a nuclear reaction network. We find that outflows produce a robust abundance pattern around the second $r$ -process peak (mass number $A \sim 130$ ), independent of model parameters, with significant production of $A < 130$ nuclei. This implies that dynamical ejecta with high electron fraction may not be required to explain the observed abundances of $r$ -process elements in metal poor stars. Disc outflows reach the third peak ( $A \sim 195$ ) in most of our simulations, although the amounts produced depend sensitively on the disc viscosity, initial mass or entropy of the torus, and nuclear physics inputs. Some of our models produce an abundance spike at $A = 132$ that is absent in the Solar system $r$ -process distribution. The spike arises from convection in the disc and depends on the treatment of nuclear heating in the simulations. We conclude that disc outflows provide an important -- and perhaps dominant -- contribution to the $r$ -process yields of compact binary mergers, and hence must be included when assessing the contribution of these systems to the inventory of $r$ -process elements in the Galaxy.
↳ astro-ph.HEastro-ph.SRgr-qcnucl-thMNRAS(2016)·165 citations
06
Electron-positron pair production in ion collisions at low velocity beyond Born approximation
R.N. Lee · A.I. Milstein
We derive the spectrum and the total cross section of electromagnetic $e^{+} e^{-}$ pair production in the collisions of two nuclei at low relative velocity $β$ . Both free-free and bound-free $e^{+} e^{-}$ pair production is considered. The parameters $η_{A, B} = Z_{A, B} α$ are assumed to be small compared to unity but arbitrary compared to $β$ ( $Z_{A, B}$ are the charge numbers of the nuclei and $α$ is the fine structure constant). Due to a suppression of the Born term by high power of $β$ , the first Coulomb correction to the amplitude appears to be important at $η_{A, B} ≳ β$ . The effect of a finite nuclear mass is discussed. In contrast to the result obtained in the infinite nuclear mass limit, the terms $\propto M^{- 2}$ are not suppressed by the high power of $β$ and may easily dominate at sufficiently small velocities.
↳ physics.atom-phnucl-thPLB(2016)·4 citations
07
Charmed Mesons and Charmonia: Three-Meson Strong Couplings
Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇷🇺 · Hagop Sazdjian🇫🇷 · Silvano Simula🇮🇹
Revisiting the strong couplings of three mesons, each of which involves at least one charm quark, proves clear disaccord between quark-model and QCD sum-rule results.
↳ hep-phnucl-thEPJ Web Conf.(2016)·1 citation
08
The $X (4140)$ , $X (4274)$ , $X (4500)$ and $X (4700)$ in the relativized quark model
Qi-Fang Lü🇨🇳 · Yu-Bing Dong🇨🇳
We investigate the masses of $cs c ˉ s ˉ$ tetraquark states in a diquark-antidiquark picture employing the relativized quark model proposed by Godfrey and Isgur. Only the antitriplet diquark states in color space are calculated. The diquark masses are obtained with the relativized potential firstly, and then the diquark and antidiquark are treated as the usual antiquark and quark, respectively, and the masses of the tetraquark states are obtained by solving the Schrödinger equation with the relativized potential between the diquark and antidiquark. The theoretical uncertainties induced by screening effects are also taken into account. It is found that the resonance of $X (4140)$ can be regarded as the $cs c ˉ s ˉ$ tetraquark ground states, and the $X (4700)$ can be assigned as the $2 S$ excited tetraquark state. When the internal excited diquarks are taken into account, the resonance of $X (4500)$ can be explained as the tetraquark composed of one $2 S$ scalar diquark and one scalar antidiquark. In our approach, the $X (4274)$ cannot be explained as a tetraquark state, however, it can be a good candidate of the conventional $χ_{c 1} (3^{3} P_{1})$ state. In addition, other charmonium-like states $χ_{c 0} (3915)$ , $X (4350)$ , $X (4630)$ and $X (4660)$ , as the $cs c ˉ s ˉ$ tetraquark states, are also discussed.
↳ hep-phhep-exnucl-thPRD(2016)·78 citations
09
Review of anisotropic flow correlations in ultrarelativistic heavy-ion collisions
You Zhou🇩🇰
Anisotropic flow phenomena is a key probe of the existence of Quark-Gluon Plasma. Several new observable associated with correlations between anisotropic flow harmonics are developed, which are expected to be sensitive to the initial fluctuations and transport properties of the created matter in heavy ion collisions. I review recent developments of correlations of anisotropic flow harmonics. The experimental measurements, together with the comparisons to theoretical model calculations, open up new opportunities of exploring novel QCD dynamics in heavy-ion collisions.
↳ nucl-exnucl-thAdv.High Energy Phys.(2016)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE