Hydrostatic Pressure of the O ( N ) φ 4 Theory in the Large N Limit

We present a self-contained calculation of the hydrostatic pressure in λφ 4 theory with O(N) internal symmetry. In the large N limit the pressure can be expressed in a resummed form. Our calculations are based on composite-operator renormal-ization. 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. The pressure computed is in complete agreement with the recent calculations of the thermodynamic pressure [1] .