Hall 123

Automated Resummation - aiming at percent accuracies at colliders

Goutam Das

RWTH, Aachen

The test of the Standard Model and new physics searches at colliders require precise theoretical predictions. The fixed order perturbative approach to calculating QCD cross-sections suffers from large logarithmiccorrections which need to be resummed to all orders in the strong couplingto restore the predictive power of perturbative QCD. This requiresan improved understanding of all order structures of QCD in the infrared region.Effective theories like the Soft-Collinear Effective Theory (SCET) are the mostsuitable for this purpose. It systematically separates physics at different scales leading to essential ingredients that need to be calculated perturbatively order-by-order in the strong coupling.In this talk, I will present a novel formalism to calculate the collinearfunctions viz. the Beam functions and the Jet functions automatically atthe next-to-next-to-leading order for an arbitrary class of observables.These perturbative objects are important ingredients in the factorization theorem in SCET. Exploiting the infrared behavior of the collinear splitting functions and using a suitable parameterization of the phase space, I will show how to completely factorize the singularities coming from the Soft and Collinear regions. This approach is well-tested for known observables like 0-Jettiness, and transverse momentum, and has produced new predictions for Angularity, jet-veto, etc. These are the last missing pieces to achieve NNLL' accuracy for many observables at the colliders which can be used to extract strong coupling and study TMDs at colliders for the first time.