Alladi Ramakrishnan Hall

Four Gluon Amplitudes at Three Loops in QCD

Taushif Ahmed

Max-Planck-Institut für Physik

In this seminar, we talk about calculating analytically all helicity amplitudes for four-particle scattering in massless on-shell quantum chromodynamics (QCD) to three loops order in perturbation theory. Performing the integration-by-parts (IBP) reductions and simplifying huge analytical expressions are the prime bottlenecks of these groundbreaking calculations. By developing semi-automatic frameworks with the help of several state-of-the-art techniques we overcome these bottlenecks. These amplitudes are key ingredients for the theoretical predictions of dijet observables at next-to-next-to-next-to-leading order (N3LO) in QCD. Production of dijet is one of the most frequently occurring and cornerstone processes at the large hadron collider (LHC). The exploitation of abundant amount of dijet data at the LHC depends on reliable theoretical computations. The state-of-the-art next-to-next-to-leading order (NNLO) results of dijet observables lack stable dependence on renormalisation and factorisation scales. Hence, we need to aim for going beyond NNLO for more reliable theoretical results. Besides phenomenological importance, the analytical results will open a new door for performing a detailed analysis of analytic properties of scattering amplitude which is crucial in improving our understanding of higher-order perturbation theory.