[Rivet] possible issues with WFinder?

[Raghav Kunnawalkam Elayavalli]

Dear David,

Yeah that was my guess as well w.r.t the neutrinos was missing ET, but in pp simulations there shoudnt this large of a difference. Here is a simple rivet analysis with a hepMC files that i generated for W+Jet events.
Cheers
Raghav
On May 19, 2016, at 11:56 PM, David Grellscheid <david.grellscheid at durham.ac.uk<mailto:david.grellscheid at durham.ac.uk>> wrote:

Hi Raghav,

it would help us a lot if you could implement both methods in a single minimal analysis cc file which is ready to be used, filling one histo each.

One difference I can see at the moment is that individual neutrinos aren't used in WFinder. It uses missing E.

See you,

 David


On 19/05/2016 15:31, Raghav Kunnawalkam Elayavalli wrote:
Hi Rivet Experts,

I think there might be something happening with the WFinder in the latest version of Rivet. Ive attached two invariant mass plots here and [1] is using the WFinder and [2] is what i estimate by hand. You can see a big difference in the distributions even for pp at 2.76 TeV. When we do our heavy ion events we lose a whole lot of Z's which are recovered by estimating by hand. Yes, there are a few differences in the two methods, but between 0.1 and 0.2 in delR and missing ET cut, i dont think it should be such a huge difference?

Cheers
Raghav

[1]       WFinder wfinder(fs, Cuts::abseta < 3.0 && Cuts::pT > 20*GeV, PID::MUON, 0.0*GeV, 1000.0*GeV, 25.0*GeV, 0.2);

[cid:84252C3A-9047-425F-90A1-0527877B491B at cern.ch]
[2] in the init() method:
      IdentifiedFinalState allleptons;
      // allleptons.acceptIdPair(PID::ELECTRON);
      allleptons.acceptIdPair(PID::MUON);
      Cut cuts = Cuts::abseta < 2.5 && Cuts::pT > 20*GeV;
      DressedLeptons leptons(fs, allleptons, 0.1, cuts);
      addProjection(leptons, "leptons");

      // Leading neutrinos for Etmiss
      LeadingParticlesFinalState neutrinos(fs);
      // neutrinos.addParticleIdPair(PID::NU_E);
      neutrinos.addParticleIdPair(PID::NU_MU);
      neutrinos.setLeadingOnly(true);
      addProjection(neutrinos, "neutrinos");

in the analyze() method:
      // implementation of simple Wfinder
      const vector<DressedLepton>& leptons = applyProjection<DressedLeptons>(event, "leptons").dressedLeptons();
      Particles neutrinos = applyProjection<FinalState>(event, "neutrinos").particlesByPt();
      if (leptons.size() != 1 || (neutrinos.size() == 0)) {
vetoEvent;
      }

      FourMomentum lepton = leptons[0].momentum();
      FourMomentum p_miss = neutrinos[0].momentum();
      if (p_miss.Et() < 25.0*GeV) {
vetoEvent;
      }

      double invMass = sqrt(2.0 * lepton.pT()/GeV * p_miss.pT()/GeV * (cosh(lepton.eta()-p_miss.eta()) - cos( lepton.phi()-p_miss.phi()) ) );
      _h_W_massCheck->fill(invMass, weight);

[cid:375AF03C-519A-4CB4-B220-45CBE3297EAA at cern.ch]



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