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Equation of state and transition temperatures in the quark-hadron hybrid model

We analyze the equation of state of 2+1 flavor lattice QCD at zero baryon density by constructing the simple quark-hadron hybrid model that has both quark and hadron components simultaneously. We calculate hadron and quark contribution separately and parameterizing those to match with LQCD data. Lattice data on the equation of state are decomposed into hadron and quark components by using the model. The transition temperature is defined by the temperature at which the hadron component is equal to the quark one in the equation of state. The transition temperature thus obtained is about 215 MeV and somewhat higher than the chiral and the deconfinement pseudocritical temperatures defined by the temperature at which the susceptibility or the absolute value of the derivative of the order parameter with respect to temperature becomes maximum.