NLL BFKL and NNLO

In the limit of center-of-mass energy much greater than the momentum transfer, ŝ ≫ |t̂|, any scattering process is dominated by gluon exchange in the cross channel. Building upon this fact, the BFKL theory [ 1] models stronginteraction processes with two large and disparate scales, by resumming the radiative corrections to parton-parton scattering. This is achieved to leading logarithmic (LL) accuracy, in ln(ŝ/|t̂|), through the BFKL equation, i.e. a twodimensional integral equation which describes the evolution in transverse momentum space and moment space of the gluon propagator exchanged in the cross channel,