Title:  QCD scattering in the High-energy Limit

Speaker: Einan Gardi

Time: 14:00, May 6

Location: Room 215, No. 8 Hainayuan Building

Abstract:

I will review the theoretical research programme aimed at understanding the behaviour quark and gluon scattering amplitudes in the high-energy limit. Despite major progress of the past few years, fixed-order computations of QCD amplitudes in general kinematics are limited to either one, two or three loops, depending on the number of particles produced. The limit in which the centre-of-mass energy of the collision is taken large can only be qualitatively described upon resumming logarithmically-enhanced contributions to all orders in perturbation theory. Indeed, it has long been known that the leading energy logarithms simply exponentiate, a phenomenon known as gluon Reggeization, leading to power-like dependence on the energy. This form of resummation of the expansion can be investigated by establishing evolution equations in the logarithm of the energy. I will describe the challenges that arise upon extending this idea beyond the leading or next-to-leading towers of logarithms and share some recent exciting insights on the path to overcome these challenges.

Biography:

Einan Gardi is a Professor of Theoretical Physics at the University of Edinburgh in Scotland. He received his PhD in 1999 in Tel-Aviv University and worked as a postdoctoral researcher in  Europe, in Paris, Geneva (CERN), Regensburg and Cambridge. He joined the University of Edinburgh in 2007. Between 2015 and 2023 he served as Director of the Higgs Centre for Theoretical Physics.

Professor Gardi is an expert in Quantum Field Theory and its applications to collider and flavour physics. He contributed to the development of methods in perturbative Quantum Chromodynamics including factorization, resummation and power-correction techniques in a range of applications. Over the past decade his research focused on general properties of scattering amplitudes, such as their infrared singularity structure and their behaviour in special kinematic limits, such as the high-energy limit. He has also contributed to understanding certain mathematical aspects of Feynman integrals, including their analytic and algebraic structure and their asymptotic expansions.