SU(2) Yang-Mills theory in the Savvidy background at finite temperature and chemical potential

The one-loop effective energy density of a pure SU(2) Yang-Mills theory in the Savvidy background at finite temperature and chemical potential is examined with emphasis on the unstable modes. After identifying the stable and unstable modes, the stable modes are treated in the quadratic approximation. For the unstable modes, the full expansion including the cubic and the quartic terms in the fluctuations is used. The functional integrals for the unstable modes are evaluated and added to the results for the stable modes. The resulting energy density is found to be real, coinciding with the real part of the energy density in the quadratic approximation of earlier study. There is now no imaginary part. Numerical results are presented for the variation of the energy density with temperature for various choices of the chemical potential.