- July 19, 2022, 2:30 pm US/Central
- Wilson Hall, Curia II
- Massimiliano Grazzini, University of Zurich
- Stefan Hoeche
The precision of LHC data has reached a level that NNLO QCD predictions are required for most of the relevant processes. Despite the enormous progress in higher-order computations, that now reaches even N3LO QCD for some benchmark processes, only a few of the NNLO calculations are really available to the community. We review the recent progress in NNLO computations and describe the status of the parton level generator MATRIX, which is based on the $q_T$ subtraction formalism. The latter has proven to be a very effective method to carry out higher order QCD computations when colour singlets and/or heavy quarks are produced. In the case in which hard jets appear at Born level $q_T$ cannot be directly applied, and jettiness subtraction is considered as a natural extension. We discuss a new variable, alternative to jettiness, that smoothly captures the N+1 to N-jet transition. This variable, that we dub $k_T^{ness}$, represents an effective transverse momentum controlling the singularities of the N+1-jet cross section when the additional jet is unresolved. The $k_T^{ness}$ variable offers novel opportunities to perform higher-order QCD calculations. We study the singular behavior of the N+1-jet cross section as $k_T^{\ness}\to 0$ and, as a phenomenological application, we use the ensuing results to evaluate NLO corrections to some sample jet processes at the LHC. We show that our variable performs extremely well as a resolution variable and appears to be very stable with respect to hadronization and multiple-partonic interactions.