Hydrostatic Pressure of the $O(N)\Phi^{4}$ Theory in the Large N Limit

We present a self-contained calculation of the hydrostatic pressure in pressure can be expressed in a resummed form. Our calculations are based on composite-operator renormalization. As a byproduct, the renormalized (or improved) energy-momentum tensor is obtained. The Dyson-Schwinger equations are used to discuss both the mass and coupling constant renormalization. We also calculate the high-temperature expansion for the pressure in D=4. The latter is done by means of the Mellin transform technique