Triple energy correlation near the phase-space limit

Triple energy correlation near the planar limit in high-energy e+e- annihilation is calculated in QCD to the double-logarithmic approximation. The result is the exponentiated squared logarithm of an appropriately chosen variable. This is characteristic of semi-inclusive cross sections with more than one large invariant. In the course of deriving the result we have introduced generalized Sudakov variables, which will be useful calculating other processes, where three hard partons emit soft gluons