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Nuclear Theory·nucl-th

Monday·April 30, 2018

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    Finite-temperature relativistic nuclear field theory: an application to the dipole response

    Elena Litvinova🇺🇸 · Herlik Wibowo🇺🇸

    Nuclear response theory beyond the one-loop approximation is formulated for the case of finite temperature. For this purpose, the time blocking approximation to the time-dependent part of the in-medium nucleon-nucleon interaction amplitude is adopted for the thermal (imaginary-time) Green's function formalism. We found that introducing a soft blocking, instead of a sharp blocking at zero temperature, brings the Bethe-Salpeter equation to a single frequency variable equation also at finite temperatures. The method is implemented self-consistently in the framework of Quantum Hadrodynamics and designed to connect the high-energy scale of heavy mesons and the low-energy domain of nuclear medium polarization effects in a parameter-free way. In this framework, we investigate the temperature dependence of dipole spectra in the even-even nuclei Ca, Sn and Sn with a special focus on the giant dipole resonance's width problem and on the low-energy dipole strength distribution.

    nucl-thPRL(2018)·33 citations
  2. 02

    Review on the progress in nuclear fission

    Karl-Heinz Schmidt🇫🇷 · Beatriz Jurado🇫🇷

    An overview is given on some of the main advances in experimental methods, experimental results and theoretical models and ideas of the last years in the field of nuclear fission. New experimental approaches extended the availability of fissioning systems considerably and provided a full identification of all fission products in A and Z for the first time. In particular, the transition from symmetric to asymmetric fission around 226Th and some unexpected structure in the mass distributions in the fission of systems around Z = 80 to 84 as well as an extended systematics of the odd-even effect in fission fragment Z distributions have been measured [A. N. Andreyev et al., Rep. Progr. Phys. 81 (2018) 016301]. Three classes of theoretical descriptions of fission presently appear to be the most promising or the most successful ones: Self-consistent quantum-mechanical models fully consider the quantum-mechanical features of the fission process. Intense efforts are presently made to develop suitable theoretical tools [N. Schunck, L. M. Robledo, Rep. Prog. Phys. 79 (2016) 116301] for modeling the non-equilibrium, large-amplitude collective motion leading to fission. Stochastic, essentially classical models provide a fully developed technical framework. The main features of the fission-fragment mass distribution are well reproduced from mercury to fermium and beyond [P. Möller, J. Randrup, Phys. Rev. C 91 (2015) 044316]. In an alternative semi-empirical approach [K.-H. Schmidt et al., Nucl. Data Sheets 131 (2016) 107], considerable progress in describing the fission observables has been achieved by combining several general theoretical concepts. This new approach reveals a high degree of regularity and allows calculating high-quality data with a unique parameter set for a large number of systems and an extended excitation-energy range.

    nucl-thRept.Prog.Phys.(2018)·166 citations
  3. 03

    Net baryon diffusion in fluid dynamic simulations of relativistic heavy-ion collisions

    Gabriel S. Denicol🇧🇷 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Akihiko Monnai🇫🇷 · Björn Schenke🇺🇸 · Chun Shen🇺🇸

    A hybrid (hydrodynamics + hadronic transport) theoretical framework is assembled to model the bulk dynamics of relativistic heavy-ion collisions at energies accessible in the Beam Energy Scan (BES) program at the Relativistic Heavy-Ion Collider (RHIC) and the NA61/SHINE experiment at CERN. The system's energy-momentum tensor and net baryon current are evolved according to relativistic hydrodynamics with finite shear viscosity and non-zero net baryon diffusion. Our hydrodynamic description is matched to a hadronic transport model in the dilute region. With this fully integrated theoretical framework, we present a pilot study of the hadronic chemistry, particle spectra, and anisotropic flow. Phenomenological effects of a non-zero net-baryon current and its diffusion on hadronic observables are presented for the first time. The importance of the hadronic transport phase is also investigated.

    nucl-thhep-phnucl-exPRC(2018)·217 citations

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first authorsco-authorsvia INSPIRE