Factorisation and resummation at subleading power

Advancing the precision of theoretical predictions is a key ingredient in the ongoing Standard Model tests and searches for physics beyond our current paradigm. Soft Collinear Effective Theory (SCET) has been successfully applied to improve the precision of many important observables in collider physics. It is now standard practice to use SCET to derive factorisation theorems and apply renormalisation group (RG) methods to perform the leading power resummation of large logarithmic contributions that appear in regions of phase space with disparate energy scales. In this talk, I will discuss the recent developments in taking the step beyond the leading term in the power expansion. Focusing on the threshold Drell-Yan process, I will explain how to derive the general factorisation formula and discuss the new objects that emerge beyond leading power: collinear jet functions and generalised soft functions. I will present the leading logarithmic solution of the RG equations and describe challenges in increasing the logarithmic accuracy of resummation at next-to-leading power.

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