The High-Energy Limit of 2 to 2 Partonic Scattering Amplitudes
Einan Gardi
University of Edinburgh
Tue, May. 21st 2019, 16:00
Salle Claude Itzykson, Bât. 774, Orme des Merisiers

Recently, there has been significant progress in computing scattering amplitudes in the high-energy limit using rapidity evolution equations. I describe the state-of-the-art and demonstrate the interplay between exponentiation of high-energy logarithms and that of infrared singularities. The focus in this talk is the imaginary part of 2 to 2 partonic amplitudes, which can be determined by solving the BFKL equation. I demonstrate that the wavefunction is infrared finite, and that its evolution closes in the soft approximation. Within this approximation I derive a closed-form solution for the amplitude in dimensional regularization, which fixes the soft anomalous dimension to all orders at NLL accuracy. I then turn to finite contributions of the amplitude and show that the remaining ``hard'' contributions can be determined algorithmically, by iteratively solving the BFKL equation in exactly two dimensions within the class of single-valued harmonic polylogarithms. To conclude I present numerical results and analyse large-order behaviour of the amplitude.

Contact : lbervas


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