Nuclear Theory·nucl-th

Tuesday·June 28, 2016

10 papers—6 primary·4 cross-listed

01
Azimuthal instabilities of the Gribov-Levin-Ryskin equation
Guillermo Gambini🇧🇷 · Giorgio Torrieri🇧🇷
We introduce the phenomenology of elliptic flow in nuclear collisions, and argue that its scaling across energies, rapidities and system sizes could be suggestive of a QCD-based rather than a hydrodynamical explanation. As a hypothesis for such an explanation, we show that the GLR equation develops unstable modes when the parton distribution function is generalized to depend on azimuthal angle. This generally means the structure function aquires an azimuthal dependence. We argue that this process is a plausible alternative explanation for the origin of elliptic flow, one that naturally respects the scaling experimentally observed.
nucl-thhep-phEPJA(2017)·9 citations
02
The calculation of single-nucleon energies of nuclei by considering two-body effective interaction, n(k,rho), and a Hartree-Fock inspired scheme
Hodjat Mariji🇵🇹
The nucleon single-particle energies (SPEs) of the selected nuclei, that is, 16O, 40Ca, and 56Ni, are obtained by using the diagonal matrix elements of two-body effective interaction, which generated through the lowest order constrained variational (LOCV) calculations for the symmetric nuclear matter with the AV18 phenomenological nucleon-nucleon potential. The SPEs at the major levels of nuclei are calculated by employing a Hartree-Fock inspired scheme in the spherical harmonic oscillator basis. In the scheme, the correlation influences are taken into account by imposing the nucleon effective mass factor on the radial wave functions of the major levels. Replacing the density-dependent one-body momentum distribution functions of nucleons, n(k,rho), with the Heaviside functions, the role of n(k,rho) on the nucleon SPEs at the major levels of the selected closed shell nuclei, is investigated. The best fit of spin-orbit splitting is taken into account when correcting the major levels of the nuclei by using the parameterized Wood-Saxon potential and the AV18 density-dependent mean field potential which is constructed by the LOCV method. Considering the point-like protons in the spherical Coulomb potential well, the single-proton energies are corrected. The results show the importance of including n(k,rho), instead of the Heaviside functions, in the calculation of nucleon SPEs at the different levels, particularly the valence levels, of the closed shell nuclei.
nucl-thAdv.High Energy Phys.(2016)·0 citations
03
Proton-skins in momentum space and neutron-skins in coordinate space in heavy nuclei
Bao-Jun Cai · Bao-An Li · Lie-Wen Chen
Neutron-skins in coordinate space and proton-skins in momentum space are predicted to coexist in heavy nuclei and their correlation is governed by Liouville's theorem and Heisenberg's uncertainty principle. An analysis of their correlation within a further extended Thomas-Fermi (ETF $^{+}$ ) approximation incorporating effects of nucleon short-range correlations reveals generally that protons move faster than neutrons in neutron-skins of heavy nuclei.
nucl-thastro-ph.SRnucl-exPRC(2016)·21 citations
04
Influence of Surface Tension on Nuclear Collective Properties
N.G. Goncharova
Rigidities of even-even nuclei were estimated and compared with nuclear charge radii. Correlation of maximal nuclear rigidities with minimal values of r0 parameters was revealed. Influence of effective surface tension on nuclear properties was discussed.
nucl-thPhys.Part.Nucl.(2017)·1 citation
05
Axial anomaly and energy dependence of hyperon polarization in Heavy-Ion Collisions
A. Sorin🇷🇺 · O. Teryaev🇷🇺
We address the issue of energy and charge dependence of global polarization of $Λ$ hyperons in peripheral $A u - A u$ collisions recently observed by the STAR collaboration at RHIC. We compare different contributions to the anomalous mechanism relating polarization to vorticity and hydrodynamic helicity in QCD matter. We stress that the suppression of the gravitational anomaly contribution in strongly correlated matter observed in lattice simulations confirms our earlier prediction of rapid decrease of polarization with increasing collision energy. Our mechanism leads to polarization of $Λ ˉ$ of the same sign and larger magnitude than the polarization of $Λ$ . The energy and charge dependence of polarization is suggested as a sensitive probe of fine details of QCD matter structure.
nucl-thhep-lathep-phnucl-exPRC(2017)·54 citations
06
Sequential bottomonium production at high temperatures
P. Petreczky🇺🇸 · C. Young🇺🇸
Bottomonium production in heavy ion collisions is modified compared with any simple extrapolation from elementary collisions. This modification is most likely caused by the presence of a deconfined system of quarks and gluons for times of several fm/c. In such a medium, bottomonium can be destroyed, but the constituent bottom quarks will likely stay spatially correlated due to small mean free paths in this system. With these facts in mind, we describe bottomonium formation with a coupled set of equations. A rate equation describes the destruction of $Υ (1 S)$ particles, while a Langevin equation describes how the bottom quarks stay correlated for a sufficiently long time so that recombination into bottomonia is possible. We show that within this approach it is possible to understand the magnitude of $Υ (1 S)$ suppression in heavy ion collisions and the larger suppression of the $Υ (2 S)$ state, implying that the reduction in the ratio of $Υ (1 S) /Υ (2 S)$ yield in heavy ion collision does not necessarily correspond to sequential melting picture.
nucl-thhep-phFew Body Syst.(2017)·7 citations
07
Chiral magnetic effect by synthetic gauge fields
Tomoya Hayata🇯🇵 · Masahito Ueda🇯🇵
We study the dynamical generation of the chiral chemical potential in a Weyl metal constructed from a three-dimensional optical lattice and subject to synthetic gauge fields. By numerically solving the Boltzmann equation with the Berry curvature in the presence of parallel synthetic electric and magnetic fields, we find that the spectral flow and the ensuing chiral magnetic current emerge. We show that the spectral flow and the chiral chemical potential can be probed by time-of-flight imaging.
↳ cond-mat.quant-gascond-mat.mes-hallhep-phhep-th+11 citation
08
Yang-Mills correlators across the deconfinement phase transition
U. Reinosa🇫🇷 · J. Serreau🇫🇷 · M. Tissier🇫🇷 · A. Tresmontant🇫🇷
We compute the finite temperature ghost and gluon propagators of Yang-Mills theory in the Landau-DeWitt gauge. The background field that enters the definition of the latter is intimately related with the (gauge-invariant) Polyakov loop and serves as an equivalent order parameter for the deconfinement transition. We use an effective gauge-fixed description where the nonperturbative infrared dynamics of the theory is parametrized by a gluon mass which, as argued elsewhere, may originate from the Gribov ambiguity. In this scheme, one can perform consistent perturbative calculations down to infrared momenta, which have been shown to correctly describe the phase diagram of Yang-Mills theories in four dimensions as well as the zero-temperature correlators computed in lattice simulations. In this article, we provide the one-loop expressions of the finite temperature Landau-DeWitt ghost and gluon propagators for a large class of gauge groups and present explicit results for the SU(2) case. These are substantially different from those previously obtained in the Landau gauge, which corresponds to a vanishing background field. The nonanalyticity of the order parameter across the transition is directly imprinted onto the propagators in the various color modes. In the SU(2) case, this leads, for instance, to a cusp in the electric and magnetic gluon susceptibilities as well as similar signatures in the ghost sector. We mention the possibility that such distinctive features of the transition could be measured in lattice simulations in the background field gauge studied here.
↳ hep-thhep-lathep-phnucl-thPRD(2017)·33 citations
09
Finite-Size Scaling of Non-Gaussian Fluctuations Near the QCD Critical Point
Roy A. Lacey (1,2)🇺🇸 · Peifeng Liu (1,2)🇺🇸 · Niseem Magdy (1)🇺🇸 · B. Schweid (1,2)🇺🇸 · N. N. Ajitanand (1) ((1) Department of Chemistry, Stony Brook University, (2) Dept. of Physics, Stony Brook University)🇺🇸
An effective Finite-Size Scaling (FSS) of moment products from recent STAR measurements of the variance $σ$ , skewness $S$ and kurtosis $κ$ of net-proton multiplicity distributions, are reported for a broad range of collision centralities in Au+Au ( $s_{N N} = 7.7 - 200$ GeV) collisions. The products $S σ$ and $κ σ^{2}$ , which are directly related to the hgher-order baryon number susceptibility ratios $χ_{B}^{(3)} / χ_{B}^{(2)}$ and $χ_{B}^{(4)} / χ_{B}^{(2)}$ , show scaling patterns consistent with earlier indications for a second order phase transition at a critical end point (CEP) in the plane of temperature vs. baryon chemical potential ( $T, μ_{B}$ ) of the QCD phase diagram. The resulting scaling functions validate the earlier estimates of $T^{cep} \sim 165$ MeV and $μ_{B}^{cep} \sim 95$ MeV for the location of the CEP, and the critical exponents used to assign its 3D Ising model universality class.
↳ nucl-exhep-exnucl-th11 citations
10
Hidden-charm pentaquarks as a meson-baryon molecule with coupled channels for $D ˉ^{(*)} Λ_{c}$ and $D ˉ^{(*)} Σ_{c}^{(*)}$
Yasuhiro Yamaguchi🇮🇹 · Elena Santopinto🇮🇹
The recent observation of two hidden-charm pentaquark states by LHCb collaborations prompted us to investigate the exotic states close to the $D ˉ Λ_{c}$ , $D ˉ^{*} Λ_{c}$ , $D ˉ Σ_{c}$ , $D ˉ Σ_{c}^{*}$ , $D ˉ^{*} Σ_{c}$ and $D ˉ^{*} Σ_{c}^{*}$ thresholds. We therefore studied the hadronic molecules that form the coupled-channel system of $D ˉ^{(*)} Λ_{c}$ and $D ˉ^{(*)} Σ_{c}^{(*)}$ . As the heavy quark spin symmetry manifests the mass degenerations of $D ˉ$ and $D ˉ^{*}$ mesons, and of $Σ_{c}$ and $Σ_{c}^{*}$ baryons, the coupled channels of $D ˉ^{(*)} Σ_{c}^{(*)}$ are important in these molecules. In addition, we consider the coupling to the $D ˉ^{(*)} Λ_{c}$ channel whose thresholds are near the $D ˉ^{(*)} Σ_{c}^{(*)}$ thresholds, and the coupling to the state with nonzero orbital angular momentum mixed by the tensor force. This full coupled channel analysis of $D ˉ^{(*)} Λ_{c} - D ˉ^{(*)} Σ_{c}^{(*)}$ with larger orbital angular momentum has never been performed before. By solving the coupled-channel Schrödinger equations with the one meson exchange potentials that respected to the heavy quark spin and chiral symmetries, we studied the hidden-charm hadronic molecules with $I (J^{P}) = 1/2 (3/ 2^{\pm})$ and $1/2 (5/ 2^{\pm})$ . We conclude that the $J^{P}$ assignment of the observed pentaquarks is $3/ 2^{+}$ for $P_{c}^{+} (4380)$ and $5/ 2^{-}$ for $P_{c}^{+} (4450)$ , which is agreement with the results of the LHCb analysis. In addition, we give predictions for other $J^{P} = 3/ 2^{\pm}$ states at 4136.0, 4307.9 and 4348.7 MeV in $J^{P} = 3/ 2^{-}$ , and 4206.7 MeV in $J^{P} = 3/ 2^{+}$ , which can be further investigated by means of experiment.
↳ hep-phnucl-thPRD(2017)·83 citations

Affiliations

first authorsco-authorsvia INSPIRE