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Nuclear Theory·nucl-th

Wednesday·October 26, 2016

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Quasiparticle anisotropic hydrodynamics

    Mubarak Alqahtani🇺🇸 · Michael Strickland🇺🇸

    We study an azimuthally-symmetric boost-invariant quark-gluon plasma using quasiparticle anisotropic hydrodynamics including the effects of both shear and bulk viscosities. We compare results obtained using the quasiparticle method with the standard anisotropic hydrodynamics and viscous hydrodynamics. We consider the predictions of the three methods for the differential particle spectra and mean transverse momentum. We find that the three methods agree for small shear viscosity to entropy density ratio, , but show differences at large . Additionally, we find that the standard anisotropic hydrodynamics method shows suppressed production at low transverse-momentum compared to the other two methods, and the bulk-viscous correction can drive the primordial particle spectra negative at large in viscous hydrodynamics.

    nucl-thhep-phJ.Phys.Conf.Ser.(2017)·4 citations
  2. 02

    Impact of new data for neutron-rich heavy nuclei on theoretical models for -process nucleosynthesis

    Toshitaka Kajino · Grant J. Mathews

    Current models for the process are summarized with an emphasis on the key constraints from both nuclear physics measurements and astronomical observations. In particular, we analyze the importance of nuclear physics input such as beta-decay rates; nuclear masses; neutron-capture cross sections; beta-delayed neutron emission; probability of spontaneous fission, beta- and neutron-induced fission, fission fragment mass distributions; neutrino-induced reaction cross sections, etc. We highlight the effects on models for -process nucleosynthesis of newly measured -decay half-lives, masses, and spectroscopy of neutron-rich nuclei near the -process path. We overview r-process nucleosynthesis in the neutrino driven wind above the proto-neutron star in core collapse supernovae along with the possibility of magneto-hydrodynamic jets from rotating supernova explosion models. We also consider the possibility of neutron star mergers as an r-process environment. A key outcome of newly measured nuclear properties far from stability is the degree of shell quenching for neutron rich isotopes near the closed neutron shells. This leads to important constraints on the sites for -process nucleosynthesis in which freezeout occurs on a rapid timescale.

    nucl-thastro-ph.HEastro-ph.SRRept.Prog.Phys.(2017)·29 citations
  3. 03

    To CME or not to CME? Implications of p+Pb measurements of the chiral magnetic effect in heavy ion collisions

    R. Belmont🇺🇸 · J.L. Nagle🇺🇸

    The Chiral Magnetic Effect (CME) is a fundamental prediction of QCD, and various observables have been proposed in heavy ion collisions to access this physics. Recently the CMS Collaboration \cite{Khachatryan:2016got} has reported results from p+Pb collisions at 5.02 TeV on one such observable, the three-point correlator. The results are strikingly similar to those measured at the same particle multiplicity in Pb+Pb collisions, which have been attributed to the CME. This similarity, combined with two key assumptions about the magnetic field in p+Pb collisions, presents a major challenge to the CME picture. These two assumptions as stated in the CMS paper are (1) that the magnetic field in p+Pb collisions is smaller than that in Pb+Pb collisions and (2) that the magnetic field direction is uncorrelated with the flow angle. We test these two postulates in the Monte Carlo Glauber framework and find that the magnetic fields are not significantly smaller in central p+Pb collisions, however the magnetic field direction and the flow angle are indeed uncorrelated. The second finding alone gives strong evidence that the three-point correlator signal in Pb+Pb and p+Pb is not an indication of the CME. Similar measurements in d+Au over a range of energies accessible at RHIC would be elucidating. In the same calculational framework, we find that even in Pb+Pb collisions, where the magnetic field direction and the flow angle are correlated, there exist large inhomogeneities that are on the size scale of topological domains. These inhomogeneities need to be incorporated in any detailed CME calculation.

    nucl-thnucl-exPRC(2017)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE