Light clusters in dilute heavy-baryon admixed nuclear matter
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Regular Article - Theoretical Physics
Light clusters in dilute heavy-baryon admixed nuclear matter Armen Sedrakian1,2,a 1 2
Frankfurt Institute for Advanced Studies, Ruth-Moufang str. 1, 60438 Frankfurt am Main, Germany Institute of Theoretical Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław, Poland
Received: 1 September 2020 / Accepted: 26 September 2020 / Published online: 9 October 2020 © The Author(s) 2020 Communicated by David Blaschke
Abstract We study the composition of nuclear matter at sub-saturation densities, non-zero temperatures, and isospin asymmetry, under the conditions characteristic of binary neutron star mergers, stellar collapse, and low-energy heavy-ion collisions. The composition includes light clusters with mass number A ≤ 4, a heavy nucleus (56 Fe), the Δ-resonances, the isotriplet of pions, as well as the hyperon. The nucleonic mean-fields are computed from a zero-range density functional, whereas the pion-nucleon interactions are treated to leading order in chiral perturbation theory. We show that with increasing temperature and/or density the composition of matter shifts from light-cluster to heavy baryon dominated one, the transition taking place nearly independent of the magnitude of the isospin. Our findings highlight the importance of simultaneous treatment of light clusters and heavy baryons in the astrophysical and heavy-ion physics contexts.
1 Introduction The formation of light clusters in dilute, warm nuclear matter is of interest in astrophysics of binary neutron star mergers, stellar collapse, as well as in heavy-ion physics. The details of the matter composition are important for the accurate determination of transport coefficients appearing in dissipative relativistic fluid dynamics as well as the neutrino Boltzmann transport in various astrophysical scenarios. The clustering phenomenon is also of great interest in nuclear structure calculations (e.g. alpha-clustering) and heavy ion collisions in laboratory experiments. A great deal of effort during the last decade was focused on the accurate determination of the composition of dilute nuclear matter at finite temperatures and isospin asymmetry within a range of methods based on the ideas of nuclear statistical equilibrium [1–36] and virial expansion for quantum gases [37–40]. The appearance of clusters leads to a range of a e-mail:
interesting phenomena, in particular α-condensation at low temperatures [25,26,30,41–44]. In astrophysics, light clusters and their weak interactions with neutrinos were studied in detail in the context of stellar collapse and supernova physics [45–48]. The electroweak interactions of leptons with baryonic matter are also of interest in describing the transport in binary neutron star mergers, in particular the bulk viscosity [49–52] and electrical conductivity [53,54]. The formation of the heavy baryons in dense and cold nuclear matter, in particular hyperonic members of the J 1/2+ baryonic octet in combinations with the non-strange members of baryon J 3/2+ decouplet (Δ-reson
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