Les Houches

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Working plan:

1) Summary of codes for EW automation

 Contributions from GOSAM, MadGraph5_aMC@NLO, OPENLOOPS, Recola, ...

2) Technical comparison of EW NLO cross sections

 Processes:  pp -> lljj     arXiv:1411.0916,   table 3 (and optionally table 4)
                                         and some related cumulative histograms
                            contributers (contact persons): 
                              Recola (denner@physik.uni-wuerzburg.de) 
                              OPENLOOPS (lindert@physik.uzh.ch)
                              ...
 
             pp -> lvjj     arXiv:1412.5157    table 3
                            contributers (contact persons): 
                              OPENLOOPS (lindert@physik.uzh.ch), 
                              MadGraph5_aMC@NLO?, 
                              GOSAM (nicolas.greiner@desy.de)
                              ...
             
             pp -> ttH      arXiv:1504.03446   table 3/4  for 13 TeV (or more energies)
                            contributers (contact persons):
                              MadGraph5_aMC@NLO (davide.pagani@uclouvain.be)
                              OPENLOOPS (lindert@physik.uzh.ch) 
                                ...

3) Comparison of Sudakov approximation with EW NLO corrections for distributions

 Processes:  pp -> lljj     arXiv:1411.0916,   table 3 and/or 4
                            contributers (contact persons): 
                            Recola (denner@physik.uni-wuerzburg.de) 
                            Chiesa et al. (mauro.chiesa@pv.infn.it; 
                                           fulvio.piccinini@pv.infn.it) 
                            Sherpa (jennifer.thompson@durham.ac.uk)
                             
             pp -> lvjj     arXiv:1412.5157    table 3
                            contributers (contact persons): 
                            OPENLOOPS (lindert@physik.uzh.ch) 
                            Chiesa et al. (mauro.chiesa@pv.infn.it; 
                                           fulvio.piccinini@pv.infn.it)
                            Sherpa (jennifer.thompson@durham.ac.uk)

4) Calculation of the ratio for sigma(pp → Z/gamma*+jets)/sigma(pp → gamma+jets) and comparison to data

    contributors (contact persons): 
      CMS (vitaliano.ciulli@cern.ch)
      OPENLOOPS (lindert@physik.uzh.ch)  
      Chiesa et al. (mauro.chiesa@pv.infn.it;
                     fulvio.piccinini@pv.infn.it)
      Sherpa (jennifer.thompson@durham.ac.uk)

Parameters according to CMS paper arXiv.1505.06250

Selection cuts for the ratio plots:

• For $Z/\gamma^{*}$ plus jets events we select:
  • two same flavour opposite sign leptons with $p_{T} > 20$ GeV and $|\eta| < 1.4$ and $71 < M_{\ell\ell} < 121 $ GeV and $p_{T}^{\ell\ell} > 100$ GeV
  • leptons are “dressed” with all photons in a cone of radius $\Delta R = 0.1$
  • at least one jet, jet selection $p_{T} > 30$ GeV and $|\eta| < 2.4$, we remove jets within a radius of $\Delta R < 0.5$ with respect to the axes of each lepton

• For $\gamma$ plus jets events we select:
  • at least a photon with $p_{T} > 100$ GeV and $|\eta| < 1.4$ (in case there is more than one photon the leading one satisfying all cuts is used)
  • the photon must be isolated, i.e. the scalar sum of the $p_T$ of all stable particle in a cone of radius $\Delta R = 0.4$ is less then 5 GeV
  • at least one jet, jet selection $p_{T} > 30$ GeV and $|\eta| < 2.4$ , we remove jets within a radius of $\Delta R < 0.5$ with respect to the axis of the photon

A Rivet analysis is being prepared to provide direct comparison with data at full particle level

Plots for the ratio:

• Z boson differential transverse momentum cross-section in an inclusive $Z/\gamma^{*}+\mathrm{jets}$
• $\gamma$ differential transverse momentum cross-section in an inclusive $\gamma+\mathrm{jets}$

in the following kinematic ranges:

• $N_{jets} \geq1$
• $N_{jets} \geq2$
• $N_{jets} \geq3$
• $H_{T} > 300$ GeV, $N_{\mathrm{jets}}\geq 1$

Points open for discussion/inputs:

• are scale uncertainties correlated among the two processes?
• is someone interested in having a Rivet routine which runs at parton level?

Input parameters

as defined in the relevant papers: