The improved quark mass density-dependent model (IQMDD) based on soliton bag model is studied at finite temperature. Appling the finite temperature field theory, the effective potential of the IQMDD model and the bag constant $B(T)$ have been calculated at different temperatures. It is shown that there is a critical temperature $T_{ C}\simeq 110 \mathrm{ MeV}$. We also calculate the soliton solutions of the IQMDD model at finite tmperature. It turns out that when $T<T_{ C}$, there is a bag constant $B(T)$ and the soliton solutions are stable. However, when $T>T_{ C}$ the bag constant $B(T)=0$ and there is no soliton solution, therefore, the confinement of quarks are removed quickly.
Categories: hep-ph nucl-th