I. Bednarek, P. Haensel, J. L. Zdunik, M. Bejger, R. Mańka
Recent measurement of mass of PSR J1614-2230 rules out most of existing
models of equation of state (EOS) of dense matter with high-density softening
due to hyperonization or a phase transition to quark matter or a boson
condensate.
We look for a solution of an apparent contradiction between the consequences
stemming from up-to-date hypernuclear data, indicating appearance of hyperons
at 3 nuclear densities and existence of a two-solar-mass neutron star.
We consider a non-linear relativistic mean field (RMF) model involving baryon
octet coupled to meson fields. An effective lagrangian includes quartic terms
in the meson fields. The values of the parameters of the model are obtained by
fitting semi-empirical parameters of nuclear matter at the saturation point, as
well as potential wells for hyperons in nuclear matter and the strength of the
Lambda-Lambda attraction in double-Lambda hypernuclei.
We propose a non-linear RMF model which is consistent with up-to-date
semiempirical nuclear and hypernuclear data and allows for neutron stars with
hyperon cores and M larger than 2 solar masses. The model involves
hidden-strangenes scalar and vector mesons, coupled to hyperons only, and
quartic terms involving vector meson fields.
Our EOS involving hyperons is stiffer than the corresponding nucleonic EOS
(with hyperons artificially suppressed) above five nuclear densities. Required
stiffening is generated by the quartic terms involving hidden-strangeness
vector meson.
View original:
http://arxiv.org/abs/1111.6942
No comments:
Post a Comment