Constraints on the nuclear symmetry energy and its density slope from the decay process

Abstract

We study the impact of the nuclear symmetry energy and its density dependence on the α-decay process. Within the framework of the preformed cluster model and the energy density formalism, we use different parameterizations of the Skyrme energy density functionals that yield different equations of state (EOS). Each EOS is characterized by a particular symmetryenergy coefficient (asym) and a corresponding density-slope parameter L. The stepwise trends of the neutron (proton) skin thickness of the involved nuclei with both asym and L do not clarify the oscillating behaviors of the α-decay half-life Tα with these quantities. We find that the change of the skin thickness after α-decay satisfactorily explains these behaviors. The presented results provide constraints on asym centered around an optimum value asym=32 MeV, and on L between 41 and 57 MeV. These values of asym and L, which indicate larger reduction of the proton-skin thickness and less increase in the neutron-skin thickness after an α-decay, yield a minimum calculated half-life with the same extracted value of the α-preformation factor inside the parent nucleus.