WG1 - VH/VBF subgroup conveners

Friday 2 Oct 2015, 16:00 → 18:00 Europe/Zurich

Vidyo

Andrea Rizzi (Universita di Pisa & INFN (IT)), Barbara Jaeger (University of Tuebingen), Elisabetta Pianori (University of Warwick (UK)), Francesco Tramontano (Universita e INFN, Napoli (IT)), Jason Nielsen (University of California,Santa Cruz (US)), Stefan Dittmaier

The meeting was intended to organize the work for Yellow Report 4.  The outline of the Yellow Report was circulated to us on 28 September, and the nominal deadline for the first draft is 15 November.  The final deadline is 31 January.
(See https://twiki.cern.ch/twiki/bin/view/LHCPhysics/LHCHXSWGHigggsRepository for details.)

The proposed sections for the “VBF and VH” chapter look fine, and we arranged for one or two subgroup conveners to take the lead for each section.

1 Fully Differential "NNLO" calculation for VBF (Stefan)
2 H+3jets at NLO+PS (Elisabetta and Barbara)
3 ggF H+3jets at NLO (Elisabetta)
4 Fully Differential "NNLO" calculation for VH (Francesco)
5 NNLOPS for VH (if ready?) (Francesco)
6 NNLO QCD corrections to differential H→ bb decay (Francesco)
7 gg→Zh+jet (recommendation and uncertainties) (Jason)
8 EW corrections (recommendation) (Stefan)

Even though the Yellow Report 4 should stand as an updated reference, we may not need to cover the same explanations and motivations that are already included in YR 3.

Stefan reported that the Standard Model parameters to be used for the calculations should be made available in the next few days.  We assume that the agreement will also include a single PDF set.

We need to agree on a common reference phase space for the calculations.  Elisabetta and Pietro will work on the phase space definition for VBF, while Andrea and Jason put together a proposal for VH.  

There was some discussion about how to define a differential cross section as a function of multi-variate discriminant values.  This seems very difficult because the discriminant mixes up the differential distributions, and there is no guarantee that the weights factorize.  Elisabetta has sent a link to Tackmann’s July LHCHXSWG talk on simplified cross sections, in which he proposes calculating cross sections in certain kinematic bins (see pp. 13-16 of that talk for VBF/VH-specific proposals).

Elisabetta suggested that we could also include comparison of different calculations or generators.  This would require coordination with program authors to define the parameters.  The comparison could be added, where appropriate, in individual sections.

Minutes by J. Nielsen