Hadron-quark transition and chiral symmetry restoration at high density

A simple phenomenological hybrid hadron-quark model with excluded volume effects of baryons and chiral dynamics is investigated. The hybrid equation of state naturally connects the low-density baryonic matter with the high-density quark matter. In the intermediate region, a phase, which cannot be regarded as pure hadron matter or pure quark matter, appears. In this model, there is a possibility that the abrupt first-order-like transition to pure quark matter induces the strong chiral symmetry restoration and the speed of sound has a large peak at considerable large density.