Augmenting NNLL resummations with event-generators and multi-jets: augmenting ARES

This work extends the ARES framework for NNLL resummations: automating calculations via the use of fixed-order event generators, and, extending the ARES method to multi-jet observables. We extend the ARES method to multi-jet observables in electron-positron annihilation, and we use this extension to perform the first NNLL resummation of the D-parameter, a three-jet event-shape.We introduce a new method to interface resummations to fixed-order event generators. Utilising this new method we interface jet-veto resummations with the fixed-order code MCFM. The result is a new code capable of resumming jet-veto effects in all processes that proceed via a colour-singlet, and completely differential in leptonic final states. We use the code to resum jet-veto effects in WW final states at the Large Hadron Collider, and place constraints on the unique dimension-six operator coupling gluons to the Higgs field

Near-to-planar three-jet events at NNLL accuracy

We extend the ARES method for next-to-next-to-leading-logarithmic (NNLL) QCD resummations to three-jet event shapes in e+e− collisions in the near-to-planar limit. In particular, we define a NNLL radiator for three hard emitters, and discuss new features of NNLL corrections arising specifically in this case. As an example, we present predictions for the D-parameter, matched to exact next-to-leading order (NLO). After inclusion of hadronisation corrections in the dispersive approach, we compare our predictions with LEP1 data

BSM W W production with a jet veto

We consider the impact on W W production of the unique dimension-six operator coupling gluons to the Higgs field. In order to study this process, we have to appropriately model the effect of a veto on additional jets. This requires the resummation of large logarithms of the ratio of the maximum jet transverse momentum and the invariant mass of the W boson pair. We have performed such resummation at the appropriate accuracy for the Standard Model (SM) background and for a signal beyond the SM (BSM), and devised a simple method to interface jet-veto resummations with fixed-order event generators. This resulted in the fast numerical code MCFM-RE, the Resummation Edition of the fixed-order code MCFM. We compared our resummed predictions with parton-shower event generators and assessed the size of effects, such as limited detector acceptances, hadronisation and the underlying event, that were not included in our resummation. We have then used the code to compare the sensitivity of W W and Z Z production at the HL-LHC to the considered higher-dimension operator. We have found that W W can provide complementary sensitivity with respect to Z Z, provided one is able to control theory uncertainties at the percent-level. Our method is general and can be applied to the production of any colour singlet, both within and beyond the SM