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Nuclear Theory·nucl-th

Monday·April 17, 2017

9 papers—7 primary·2 cross-listed

All9Primary7Cross-lists2
  1. 01

    Evolving theoretical descriptions of heavy-ion fusion :from phenomenological to microscopic approaches

    K. Hagino

    We overview the current status of theoretical approaches for heavy-ion fusion reactions at subbarrier energies. We particularly discuss theoretical challenges in the coupled-channels approach, that include i) a description of deep subbarrier hindrance of fusion cross sections, ii) the role of nuclear dissipation, iii) fusion of unstable nuclei, and iv) an interplay between fusion and multi-nucleon transfer processes. We also present results of a semi-microscopic approach to heavy-ion fusion reactions, that combines the coupled-channels approach with state-of-the-art microscopic nuclear structure calculations.

    nucl-thnucl-exEPJ Web Conf.(2017)·1 citation
  2. 02

    Catalysis of partial chiral symmetry restoration by Delta matter

    Yusuke Takeda🇯🇵 · Youngman Kim🇰🇷 · Masayasu Harada🇯🇵

    We study the phase structure of dense hadronic matter including as well as N(939) based on the parity partner structure, where the baryons have their chiral partners with a certain amount of chiral invariant masses. We show that, in symmetric matter, enters into matter in the density region of about one to four times of normal nuclear matter density, . The onset density of matter depends on the chiral invariant mass of , : The lager , the bigger the onset density. The matter of is unstable due to the existence of , and the stable -nucleon matter is realized at about , i.e., the phase transition from nuclear matter to -nucleon matter is of first order for small , and it is of second order for large . We find that, associated with the phase transition, the chiral condensate changes very rapidly, i.e., the chiral symmetry restoration is accelerated by \Delta matter. As a result of the accelerations, there appear (1535) and (1700), which are the chiral partners to N(939) and (1232), in high density matter, signaling the partial chiral symmetry restoration. Furthermore, we find that complete chiral symmetry restoration itself is delayed by matter. We also calculate the effective masses, pressure and symmetry energy to study how the transition to matter affects such physical quantities. We observe that the physical quantities change drastically at the transition density.

    nucl-thPRC(2018)·38 citations
  3. 03

    Chiral magnetic effect in isobaric collisions

    Xu-Guang Huang🇨🇳 · Wei-Tian Deng🇨🇳 · Guo-Liang Ma🇨🇳 · Gang Wang🇺🇸

    We give a numerical simulation of the generation of the magnetic field and the charge-separation signal due to the chiral magnetic effect (CME) --- the induction of an electric current by the magnetic field in a parity-odd matter --- in the collisions of isobaric nuclei, Ru + Ru and Zr + Zr, at GeV. We show that such collisions provide an ideal tool to disentangle the CME signal from the possible elliptic-flow driven background effects. We also discuss some other effects that can be tested by using the isobaric collisions.

    nucl-thnucl-exNPA(2017)·12 citations
  4. 04

    Phenomenological QCD equations of state for neutron star mergers

    Toru Kojo🇨🇳

    Thermal QCD equations of state at high baryon density are sensitive to the phase structure and the resulting excitation modes. The leading contribution at low temperature can be either ~p_F^2 T^2 (pF: Fermi momentum, T: temperature) for phases with gapless quarks, or ~T^4 for phases with gapped quarks. In the latter the thermal pressure is dominated by collective modes. Starting with a schematic quark model developed for neutron star structure, we estimate the thermal contributions and zero point energy from the Nambu-Goldstone modes by building them upon the mean field background for the color-flavor-locked quark matter. Applying the phase shift representation for thermodynamic potentials, we include not only the bound state pairs but also resonating pairs. According to the Levinson's theorem, the high energy contributions tend to cancel the pole contributions to the thermodynamics, tempering the UV behaviors in the zero point energy. Our primary target in this talk is the domain with baryon density nB as large as ~ 5-10n_0 (n_0 = 0.16 fm^{-3}: nuclear saturation density), and the temperature T of the order ~30-100 MeV. The insights into this domain may be obtained through the future detection of gravitational waves from neutron star merging events.

    nucl-thastro-ph.HEhep-phNPA(2017)·2 citations
  5. 05

    Characterization of the initial state and QGP medium from a combined Bayesian analysis of LHC data at 2.76 and 5.02 TeV

    Jonah E. Bernhard🇺🇸 · J. Scott Moreland🇺🇸 · Steffen A. Bass🇺🇸

    We perform a global Bayesian analysis of a modern event-by-event heavy-ion collision model and LHC data at = 2.76 and 5.02 TeV. After calibration, the model simultaneously describes multiplicity, transverse momentum, and flow data at both beam energies. We report new constraints on the scaling of initial-state entropy deposition and QGP transport coefficients, including a quantitative estimate of the temperature-dependent shear viscosity .

    nucl-thhep-phnucl-exNPA(2017)·21 citations
  6. 06

    Electromagnetic fields from quantum sources in heavy-ion collisions

    Balthazar Peroutka🇺🇸 · Kirill Tuchin🇺🇸

    We compute the electromagnetic field created by an ultrarelativistic charged particle in vacuum at distances comparable to the particle Compton wavelength. The wave function of the particle is governed by the Klein-Gordon equation, for a scalar particle, or the Dirac equation, for a spin-half particle. The produced electromagnetic field is essentially different in magnitude and direction from the Coulomb field, induced by a classical point charge, due to the quantum diffusion effect. Thus, a realistic computation of the electromagnetic field produced in heavy-ion collisions must be based upon the full quantum treatment of the valence quarks.

    nucl-thhep-phNPA(2017)·4 citations
  7. 07

    Flow in small and large quark-gluon plasma droplets: the role of nucleon substructure

    J. Scott Moreland🇺🇸 · Jonah E. Bernhard🇺🇸 · Weiyao Ke🇺🇸 · Steffen A. Bass🇺🇸

    We study the effects of nucleon substructure on bulk observables in proton-lead collisions at the LHC using Bayesian methodology. Substructure is added to the TRENTO parametric initial condition model using Gaussian nucleons with a variable number of Gaussian partons. We vary the number and width of these partons while recovering the desired inelastic proton-proton cross section and ensemble averaged proton density. We then run the model through a large number of minimum bias hydrodynamic simulations and measure the response of final particle production and azimuthal particle correlations to initial state properties. Once these response functions are determined, we calibrate free parameters of the model using established Bayesian methodology. We comment on the implied viability of the partonic model for describing hydrodynamic behavior in small systems.

    nucl-thnucl-exNPA(2017)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE