Multi-reggeon compound states and resummed anomalous dimensions in QCD

We perform the OPE analysis of the contribution of colour-singlet compound states of reggeized gluons to a generic hard process in QCD and calculate the spectrum of the corresponding higher twist anomalous dimensions in multi-colour limit. These states govern high energy asymptotics of the structure functions and their energies define the intercept of the Regge singularities both in the pomeron and the odderon sectors. We argue that due to nontrivial analytical properties of the energy spectrum, the twist expansion does not hold for the gluonic states with the minimal energy generating the leading Regge singularities. It is restored however after one takes into account the states with larger energies whose contribution to the Regge asymptotics is subleading