Quark deconfinement at finite temperature in the bag model

A thermodynamical description of a single hadron at finite internal temperature is given within the framework of the MIT bag model. The quark deconfinement transition is characterized by the divergence of the bag radius R(T). The radius behaves like ($T_c$ ${\mathrm{}}^4$-$T^4$ ${)}^{\mathrm{-}1/4}$ as the temperature T increases toward the critical temperature $T_c$. A possible consequence from this result combined with a percolation picture is that the normalized critical baryon-number density may behave as ${\mathrm{\rho }}_{\mathit{c}}$(T)/${\mathrm{\rho }}_{\mathit{c}}$(0)≃(1-${\mathrm{T}}^4$/${\mathrm{T}}_{\mathit{c}}$ ${\mathrm{}}^4$ ${)}^{3/4}$ when T approaches $T_c$ from below.