The Equation of State ( EoS ) of dense matter represents a central issue in the study of compact astrophysical objects and heavy ion reactions at intermediate and relativistic energies .
We have derived a nuclear EoS with nucleons and hyperons within the Brueckner-Hartree-Fock approach , and joined it with quark matter EoS .
For that , we have employed the MIT bag model , as well as the Nambu–Jona-Lasinio ( NJL ) and the Color Dielectric ( CD ) models , and found that the NS maximum masses are not larger than 1.7 solar masses .
A comparison with available data supports the idea that dense matter EoS should be soft at low density and quite stiff at high density .