We have examined the properties of neutron-rich matter and finite nuclei in the modified relativistic Hartree approximation for several values of the renormalization parameter, μ, around the standard choice of μ equal to the nucleon mass M. Observed neutron-star masses do not effectively constrain the value of μ. However, for finite nuclei the value μ/M = 0.79, suggested by nuclear matter data, provides a good account of the bulk properties with a sigma mass of about 600 MeV. This value of μ/M renders the effective three- and four-body scalar self-couplings to be zero at 60% of equilibrium nuclear matter density. We have also found that the matter part of the exchange diagram has little impact on the bulk properties of neutron stars.
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We thank C.J. Horowitz for giving us a copy of his computerc ode for finite nuclei and for discussions pertaining thereto.W e acknowledgep artial supportf rom the Department of Energy under contracts No. ~E-FG~-~~E~~~32~~~ E”AC~2-~3E~4~10ã nd DE-FG~2-~8~~4~3~Ã. grant for computing time from the Minnesota Supercomputer Institute is gratefully acknowledged.