  The cooling process of a protoneutron star is investigated with focus on its
sensitivity to properties of hot and dense matter. An equation of state, which
includes the nucleon effective mass and nuclear symmetry energy at twice the
saturation density as control parameters, is constructed for systematic
studies. The numerical code utilized in this study follows a quasi-static
evolution of a protoneutron star solving the general-relativistic stellar
structure with neutrino diffusion. The cooling timescale evaluated from the
neutrino light curve is found to be longer for the models with larger effective
masses and smaller symmetry energies at high densities. The present results are
compared with those for other equations of state and it is found that they are
consistent in terms of their dependences on the effective mass and neutron star
radius.
