Amplitudes Summer School 2017: two talks - Andrew McLeod "Determining the Soft Anomalous Dimension from General Constraints" and Theresa Abl "Exploring Reggeon bound states in strongly coupled N=4 super Yang- Mills theory"
From Einan Gardi
Title: Determining the Soft Anomalous Dimension from General Constraints 25'
Abstract: Bootstrapping techniques---wherein one imposes known constraints on an ansatz in the hope of uniquely determining the answer---have proven to be an increasingly powerful method for computing amplitudes in recent years. While the most significant progress in this direction has been made in planar maximally supersymmetric Yang- Mills theory, these techniques can be naturally extended to the types of quantities directly relevant to collider computations. One place these methods show particular promise is in the resummation of large logarithms, and we here report the successful bootstrap of the (correction to the all-order dipole contribution) of the massless soft anomalous dimension at three loops, up to an overall numerical factor.
Theresa Abl (ETH, Zurich)
Title: Exploring Reggeon bound states in strongly coupled N=4 super Yang- Mills theory 25'
Abstract: I will discuss scattering amplitudes in strongly coupled N=4 super Yang-Mills theory in the multi-Regge limit. In the strong coupling regime, the calculation of the scattering amplitudes reduces to the solution of a system of non-linear, coupled integral equations through the AdS/CFT-correspondence. These equations reduce to standard Bethe ansatz equations in the multi-Regge limit. In this kinematical regime, scattering amplitudes in N=4 SYM are physically described by bound states of effective particles, the so-called Reggeons. The six- point remainder function is fully described by a two-Reggeon bound state and is known at finite coupling. At eight external gluons a three-Reggeon bound state starts to appear about which much less is known. We investigate the three-Reggeon bound state in the strong coupling regime and try to make some generalisations to multiple-Reggeon bound states.