Speaker
Description
One of the computational bottlenecks in state-of-the-art QCD NNLO calculations matched to resummation is the computation of the non-singular contributions to the spectrum of the given resolution variable (for example, the transverse momentum $q_T$ of the color singlet).
While we have a vast set of tools for computing and resumming the singular contributions, the non-singular ones are still typically obtained from the numerical difference between the full-QCD spectrum and the NNLO expansion of the singular contributions. In practice, this implies pushing the full-QCD NLO calculation for the process with one more jet up to very low $q_T$ values, where the cross section is logarithmically enhanced and the large cancellations between the two spectra leave us with large statistical errors.
The analytical knowledge of the expansion of the full-QCD spectrum beyond the $q_T$ leading power would allow us to approximate the non-singular contributions in the small $q_T$ limit, thus eliminating the need for a numerical subtraction up to such low values of the resolution variable. In this talk, I will present a systematic way to calculate such power corrections up to NNLO within the SCET formalism.