Infrared approach to Reggeization

We present a new approach to Reggeization of gauge amplitudes, based on the universal properties of their infrared singularities. Using the dipole formula, a compact ansatz for infrared singularities of massless amplitudes, we study Reggeization of singular contributions to high-energy amplitudes for arbitrary color representations, and any logarithmic accuracy. We derive leading-logarithmic Reggeization for general cross-channel exchanges, and we show that the simplest form of Regge factorization breaks down for imaginary parts of amplitudes at next-to-leading logarithms and for real parts at next-to-next-to-leading logarithms. Our formalism applies to multiparticle amplitudes in multi-Regge kinematics, and constrains possible corrections to the dipole formula at three loops and beyond.