Improving Shower Monte Carlo accuracy with analytic resummation

by Simone Alioli (CERN)

Thursday 19 May 2016, 14:00 → 15:00 Europe/Berlin

3344 (Physikdepartment)

I will present recent results for Drell-Yan production in the GENEVA framework, as an example of how to improve Shower Monte Carlo event generators with analytical resummation. GENEVA combines the fully-differential NNLO calculation with higher-order resummation of the resolution parameter, providing a systematic assessment of perturbative uncertainties. The resulting parton-level events are further combined with parton showering and hadronization in Pythia8. For the Drell-Yan case, the 0-jettiness resummation is carried out to NNLL', which consistently incorporates all singular virtual and real NNLO corrections.  In this way, the perturbative accuracy of 0-jet-like resummation variables is significantly improved beyond the parton shower approximation. I will show comparisons with LHC measurements from ATLAS, CMS and LHCb, including a novel study of underlying-event-sensitive and event-shape observables in presence of higher-order corrections, aimed at reducing the associated theoretical uncertainties.