Seminars
Extending GENEVA to New Resolution Variables for Precise NNLO+PS Event Generation
by
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Europe/London
Bohr Conference room 6th floor (Schuster Building)
Bohr Conference room 6th floor
Schuster Building
Description
Precise predictions for LHC processes rely on combining multi-loop fixed-order perturbative calculations with parton showers. Consistently combining the two is a long-standing challenge, which becomes a critical point in the implementation of state-of-the-art NNLO QCD Monte Carlo event generators. GENEVA is one such tool, and achieves this combination by resumming a chosen "resolution variable" to high logarithmic accuracy. Even though the choice of the resolution variable is critical in determining both which logarithms are controlled to high accuracy and how naturally the calculation interfaces with the shower, until recently, most of the GENEVA implementations relied only on standard N-jettiness.
In this talk, I will present two case studies where we explore the use of new resolution variables in an NNLO+PS generator for the first time. In the first, we resum the leading-jet transverse momentum at NNLL′ precision in the process of W-W+ production, directly matching the jet-veto observable used by experimentalists to suppress top-quark backgrounds. In the second, we combine the N3LL resummation of the color-singlet transverse momentum with a pT-like definition of 1-jettiness in the context of Higgs production in heavy-quark annihilation, a process where the Higgs qT spectrum is a key handle on the Yukawa couplings to light quarks. Achieving NLL′ accuracy for the 1-jet resolution variable required revamping key parts of the GENEVA method. I will discuss them and present a selection of phenomenological results comparing with ATLAS and CMS data.