WG1 - VH/VBF subgroup

Tuesday 20 Oct 2015, 14:00 → 18:00 Europe/Zurich

42/R-001 (CERN)

General Comments:
need definition on fiducial cuts before launching calculations for differential cross section for both VBF and VH 
For VBF, as some of the tools only work for VBF-like regions, theorists will provide the minimal set of cuts needed for calculations to converge. As well, experimentalist will provide reasonable VBF cuts based on Run 1 analyses, and a joint proposal will be circulated before next meeting in two weeks.
For VH, experimentalists will circulate a proposal as well before next meeting.

1 Fully Differential "NNLO" calculation for VBF (Stefan)

- compare POWHEG+PYTHIA [used by the experiments] with NLO and NNLO predictions
- compare the effect of using and not using complex-pole-scheme [CPS], to verify that is negligible, and NNLO corrections calculated in the NWA can be applied to samples generated with CPS
- will provide, together with the definition of the fiducial region, also the list of observables to compare. In this way, any group that is interested in comparing results with NNLO prediction and contribute to the YR4 can. The list of plots will be similar to the one used in YR2.

2.  H+3jets at NLO+PS (Elisabetta and Barbara)

- will follow recommendation used in point 1

3.  ggH H+3jets at NLO  (Elisabetta)

- Gionata was present, and verbally updated us on the status of H+3jets NLO calculations. Studies on ggH contribution in VBF region are being performed, and merging between H+2jets NLO and H+3jets NLO process is underway.
- For YR4, will provide studies for the same VBF fiducial region defined for point 1 and 2

4 Fully Differential NNLO calculation for VH [Francesco]
5 NNLOPS for VH
6 NNLO QCD corrections to differential H->bb decay

- fully differential NNLOxLO/NLOxLO/NLOxNLO/NNLOxNLO cross section being calculated ([production]x[decay])  
- experimentalist would prefer to have fully differential cross sections evaluated separately for qq and gg initiated processes, as a function of pT(H), for events with 0 and 1 jet separately
- will compare NLO decay to LO decay modelled by PS, for variables such as pT(j3) and angle j3

7 gg—>ZH+jets (Jason)

- will compare LOOPTOOLS/aMC@NLO/POWHEG [in various region of phase space, to be defined by experimentalists] 
re-calculate coupling dependence, and add recommendation on uncertainties [will be in touch with authors of original calculation]
- ggZH cross section SF  is ~2. Need to define recommendation on how to use this number, and which uncertainty to assign.
- will include in YR4 comparisons between gluon initiated ZHj and ZH merged versus ZH. Will provide, together with the definition of the fiducial region, also the list of observables to compare. I