VARIATIONAL SOLUTION OF THE LOOP EQUATION IN QCD
Michael E. Agishtein, Alexander Migdal · Modern Physics Letters A · 1988
A new technique for the large N loop equation of QCD is worked out. The Wilson loop W(C) is approximated by a Gaussian functional. The parameters are fitted to the loop equation, after which the equation is satisfied up to 0.2 %. The resulting Wilson loop corresponds to linearly rising Regge trajectories. The problem of tachyon is still present, but it could be cured by iteration of the loop equation starting from this variational solution.