The present work aims to study the possible states of matter and the location of phase boundaries between hadronic gas and the quark-gluon plasma QGP. The boundary at the hadron freeze-out is also considered. Proton-proton collisions at a wide range of center of mass energies are used to examine the phase transition (entropy-temperature) diagram. Local thermodynamic equilibrium is assumed at different intervals of rapidity space. The entropy of the system is expressed in terms of the multiplicity of hadron production in each interval. However, the local temperature is estimated using the average transverse momentum. The values of the critical temperatures are found at the boundaries of the phases with a quite clear description of the states.
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