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Nuclear Theory·nucl-th

Friday·April 1, 2016

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    [Submitted on 30 Mar 2016]

    Fragmentation of Neutron Star Matter

    P. N. Alcain · C. O. Dorso

    Background: Neutron stars are astronomical systems with nucleons submitted to extreme conditions. Due to the long range coulomb repulsion between protons, the system has structural inhomogeneities. These structural inhomogeneities arise also in expanding systems, where the fragment distribution is highly dependent on the thermodynamic conditions (temperature, proton fraction, ...) and the expansion velocity. Purpose: We aim to find the different regimes of fragment distribution, and the existence of infinite clusters. Method: We study the dynamics of the nucleons with a semiclassical molecular dynamics model. Starting with an equilibrium configuration, we expand the system homogeneously until we arrive to an asymptotic configuration (i. e. very low final densities). We study the fragment distribution throughout this expansion. Results: We found the typical regimes of the asymptotic fragment distribution of an expansion: u-shaped, power law and exponential. Another key feature in our calculations is that, since the interaction between protons is long range repulsive, we do not have always an infinite fragment. We found that, as expected, the faster the expansion velocity is, the quicker the infinite fragment disappears. Conclusions: We have developed a novel graph-based tool for the identification of infinite fragments, and found a transition from U-shaped to exponential fragment mass distribution with increasing expansion rate.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1603.09362 [pdf]
    0 citations
  2. 02

    [Submitted on 31 Mar 2016]

    Mesonic Decay of Charm Hypernuclei

    Sabyasachi Ghosh🇧🇷 · Carlos E. Fontoura🇧🇷 · Gastão Krein🇧🇷

    hypernuclei are expected to have binding energies and other properties similar to those of strange hypernuclei in view of the similarity between the quark structures of the strange and charmed hyperons, namely and . One striking difference however occurs in their mesonic decays, as there is almost no Pauli blocking in the nucleonic decay of a charm hypernucleus because the final-state nucleons leave the nucleus at high energies. The nuclear medium nevertheless affects the mesonic decays of charm hypernucleus because the nuclear mean fields modify the masses of the charm hyperon. In the present communication we present results of a first investigation of the effects of finite baryon density on different weak mesonic decay channels of the baryon. We found a non-negligible reduction of the decay widths as compared to their vacuum values.

    Comments:
    Conference name : 21st International Conference on Few-Body Problems in Physics (Chicago, Illinois, USA, from May 18th to 22nd, 2015), Conference Link : http://www.phy.ohiou.edu/~fewbody/FB21Files/generalinfo.html ; Proceeding Link : http://www.epj-conferences.org/articles/epjconf/abs/2016/08/epjconf_fb2016_05016/epjconf_fb2016_05016.html
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1603.09640 [pdf]
    EPJ Web Conf.(2016)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE