Julio Parra-Martinez from UCLA

Renormalization in (SM)EFT from an on-shell perspective

Abstract:
The Standard Model Effective Field Theory (SMEFT) provides a bottom-up, systematic way to quantify and explore the effects of physics beyond the Standard Model. In this context, my talk will describe how modern on-shell methods can aid the calculation of anomalous dimensions in EFTs with higher-dimension operators. Instead of unphysical UV divergences and counterterms, the on-shell techniques focus directly on logarithms in physical quantities, and extract anomalous dimensions from their coefficients using unitarity cuts. I will present several applications of the on-shell formalism: we will prove a new multi-loop non-renormalization theorem which constrains operator mixing; we will reproduce a significant part of the one-loop anomalous dimension matrix of the SMEFT computed by Manohar et al; and we will describe the structure of the SMEFT two-loop anomalous dimension matrix. The methods described are a modest first step in developing a purely on-shell understanding of the renormalization group.