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Nuclear Theory·nucl-th

Monday·July 1, 2019

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 01

    [Submitted on 27 Jun 2019]

    Elastic Antiproton-Nucleus Scattering from Chiral Forces

    Matteo Vorabbi🇨🇦 · Michael Gennari🇨🇦 · Paolo Finelli🇮🇹 · Carlotta Giusti🇮🇹 · Petr Navrátil🇨🇦

    Elastic scattering of antiprotons off He, C, and O is described for the first time with a totally microscopic approach based on the calculation of an optical potential (OP) describing the antiproton-target interaction. The OP is derived using the recent antiproton-nucleon () chiral interaction to calculate the matrix, while the target densities are computed with the ab initio no-core shell model using chiral interactions as well. Our results are in a good agreement with the existing experimental data and the results computed at different chiral orders of the interaction display the convergence pattern expected from the theory.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1906.11984 [pdf]
    PRL(2020)·15 citations
  2. 02

    [Submitted on 28 Jun 2019]

    Nuclear effective field theory: status and perspectives

    H.-W. Hammer🇩🇪 · S. König🇩🇪 · U. van Kolck🇫🇷

    The nuclear physics landscape has been redesigned as a sequence of effective field theories (EFTs) connected to the Standard Model through symmetries and lattice simulations of Quantum Chromodynamics (QCD). EFTs in this sequence are expansions around different low-energy limits of QCD, each with its own characteristics, scales, and ranges of applicability regarding energy and number of nucleons. We review each of the three main nuclear EFTs -- Chiral, Pionless, Halo/Cluster -- highlighting their similarities, differences, and connections. In doing so, we survey the structural properties and reactions of nuclei that have been derived from the ab initio solution of the few- and many-body problem built upon EFT input.

    Comments:
    76 pages, 29 figures, version to appear in Rev. Mod. Phys
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1906.12122 [pdf]
    RMP(2020)·569 citations
  3. 03

    [Submitted on 28 Jun 2019]

    Number conserving particle-hole RPA for superfluid nuclei

    J. Dukelsky🇪🇸 · J.E. García-Ramos🇪🇸 · J.M. Arias🇪🇸 · P. Pérez-Fernández🇪🇸 · P. Schuck🇫🇷

    We present a number conserving particle-hole RPA theory for collective excitations in the transition from normal to superfluid nuclei. The method derives from an RPA theory developed long ago in quantum chemistry using antisymmetric geminal powers, or equivalently number projected HFB states, as reference states. We show within a minimal model of pairing plus monopole interactions that the number conserving particle-hole RPA excitations evolve smoothly across the superfluid phase transition close to the exact results, contrary to particle-hole RPA in the normal phase and quasiparticle RPA in the superfluid phase that require a change of basis at the broken symmetry point. The new formalism can be applied in a straightforward manner to study particle-hole excitations on top of a number projected HFB state.

    Comments:
    Under revision in PLB
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1906.12217 [pdf]
    PLB(2019)·5 citations
  4. 04

    [Submitted on 28 Jun 2019]

    Suppression of elliptic flow without viscosity

    Adam Takacs🇳🇴 · Denes Molnar🇭🇺

    We investigate fluid-to-particle conversion using the usual Cooper-Frye approach but with more general local equilibrium distributions than the Boltzmann or Bose/Fermi distributions typically used. Even though we study ideal fluids (i.e., shear stress and bulk pressure are zero everywhere), we find a suppression of elliptic flow (v2) at high transverse momenta (pT>1.5 GeV/c), relative to results obtained with the traditional Boltzmann distributions. The non-viscous suppression shows qualitatively similar features to the well-known shear viscous suppression of v2; for example, it increases with pT, and it is smaller for heavier species as seen in self-consistent kinetic theory calculations. Our results question whether all of the v2 suppression seen in the data can be attributed to viscous effects, and indicate that shear viscosities extracted from RHIC and LHC elliptic flow data might be overestimated.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1906.12311 [pdf]
    8 citations
  5. 05

    [Submitted on 28 Jun 2019]

    How AMPT generates large elliptic flow with small cross sections

    Denes Molnar (Dept. of Physics and Astronomy, Purdue University, West Lafayette, IN)🇺🇸

    We resolve the long-standing open question of how the transport model AMPT manages to generate sufficiently high elliptic flow (v2) in A+A reactions with only few-millibarn 2->2 partonic cross sections - in apparent contradiction with an early study by Molnar and Gyulassy. Through detailed comparisons with the covariant Molnar's Parton Cascade (MPC), we pinpoint which features of initial conditions, interactions, and dynamics encoded in the partonic stage of AMPT allow it to circumvent the "opacity puzzle" at RHIC.

    Comments:
    7 pages, 7 EPS figures, REVTeX style
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1906.12313 [pdf]
    9 citations

Affiliations

first authorsco-authorsvia INSPIRE