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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
  5. 05

    In-medium dispersion relations of charmonia studied by maximum entropy method

    Atsuro Ikeda🇯🇵 · Masayuki Asakawa🇯🇵 · Masakiyo Kitazawa🇯🇵

    We study in-medium spectral properties of charmonia in the vector and pseudoscalar channels at nonzero momenta on quenched lattices, especially focusing on their dispersion relation and weight of the peak. We measure the lattice Euclidean correlation functions with nonzero momenta on the anisotropic quenched lattices and study the spectral functions with the maximum entropy method. The dispersion relations of charmonia and the momentum dependence of the weight of the peak are analyzed with the maximum entropy method together with the errors estimated probabilistically in this method. We find significant increase of the masses of charmonia in medium. It is also found that the functional form of the charmonium dispersion relations is not changed from that in the vacuum within the error even at for all the channels we analyzed.

    ↳ hep-lathep-phnucl-thPRD(2017)·21 citations
  6. 06

    Equation of State for SU(3) Gauge Theory via the Energy-Momentum Tensor under Gradient Flow

    Masakiyo Kitazawa🇯🇵 · Takumi Iritani🇯🇵 · Masayuki Asakawa🇯🇵 · Tetsuo Hatsuda🇯🇵 · Hiroshi Suzuki🇯🇵

    The energy density and the pressure of SU(3) gauge theory at finite temperature are studied by direct lattice measurements of the renormalized energy-momentum tensor obtained by the gradient flow. Numerical analyses are carried out with -- corresponding to the lattice spacing --. The spatial (temporal) sizes are chosen to be , , (, , , , ) with the aspect ratio, . Double extrapolation, (the continuum limit) followed by (the zero flow-time limit), is taken using the numerical data. Above the critical temperature, the thermodynamic quantities are obtained with a few percent precision including statistical and systematic errors. The results are in good agreement with previous high-precision data obtained by using the integral method.

    ↳ hep-lathep-phnucl-thPRD(2016)·101 citations
  7. 07

    Analytical On-shell Calculation of Higher Order Scattering: Massive Particles

    Barry R. Holstein🇺🇸

    We demonstrate that the use of on-shell methods, involving calculation of the discontinuity across the t-channel cut associated with the exchange of a pair of massless particles, can be used to evaluate loop contributions to both the electromagnetic and gravitational scattering of massive systems. In the gravitational case, the use of factorization permits a straightforward and algebraic calculation of higher order scattering results, which were obtained previously by much more arduous Feynman diagram techniques.

    ↳ hep-phgr-qchep-thnucl-th9 citations

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first authorsco-authorsvia INSPIRE