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CMS_2019_I1705068

Measurement of associated production of a W boson and a charm quark in proton-proton collisions at 13 TeV
Experiment: CMS (LHC)
Inspire ID: 1705068
Status: VALIDATED
Authors:
• cms-pag-conveners-smp@cern.ch
• Svenja.Karen.Pflitsch@cern.ch
• Katerina.Lipka@cern.ch
References:
• Eur.Phys.J. C79 (2019) no.3, 269
• DOI:10.1140/epjc/s10052-019-6752-1
• arXiv: 1811.10021
• CMS-SMP-17-014
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
• 13 TeV $pp \to W+c$.

Measurements are presented of associated production of a W boson and a charm quark (W+c) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of $35.7 fb^{-1}$ collected by the CMS experiment at the CERN LHC. The W bosons are identified by their decay into a muon and a neutrino. The charm quarks are tagged via the full reconstruction of $D*(2010)^{\pm}$ mesons that decay via $D*(2010)^{\pm} \to D^{0} + \pi^{pm} \to K^{\mp} + \pi^{pm} + \pi^{pm}$. A parton-level cross section is measured in the fiducial region defined by the muon transverse momentum $\p_{T}^{\mu} > 26 GeV$, muon pseudorapidity $\abs{\eta^{\mu}} < 2.4$, and charm quark transverse momentum $p_{T}^{c} > 5\text{GeV}$. The cross section is also measured differentially as a function of the pseudorapidity of the muon from the W boson decay. A particle-level cross section is measured in the fiducial region defined by the muon transverse momentum $\p_{T}^{\mu} > 26 GeV$, muon pseudorapidity $\abs{\eta^{\mu}} < 2.4$, D*(2010)^{\pm} transverse momentum $p_{T}^{D*} > 5\text{GeV}$ and D*(2010)^{\pm} pseudorapidity $\abs{\eta^{D*}} < 2.4$. The particle-level cross section has been implemented in the Rivet plugin.

Source code: CMS_2019_I1705068.cc
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/FinalState.hh" #include "Rivet/Projections/FastJets.hh" #include "Rivet/Projections/WFinder.hh" #include "Rivet/Projections/UnstableParticles.hh" namespace Rivet { // Measurement of associated production of a W boson and a charm quark in proton-proton collisions at 13 TeV class CMS_2019_I1705068 : public Analysis { public: DEFAULT_RIVET_ANALYSIS_CTOR(CMS_2019_I1705068); void init() { // Projections FinalState fs; WFinder wfinder_mu(fs, Cuts::abseta < 2.4 && Cuts::pT > 0*GeV, PID::MUON, 0*GeV, 1000000*GeV, 0*GeV, 0.1, WFinder::ChargedLeptons::PROMPT, WFinder::ClusterPhotons::NODECAY, WFinder::AddPhotons::NO, WFinder::MassWindow::MT); declare(wfinder_mu, "WFinder_mu"); UnstableParticles dst(Cuts::pT > 5*GeV && Cuts::abseta < 2.4); declare(dst, "Dstar"); // Particle-Level histograms from the paper: book(_hist_WplusMinus_MuAbseta, "d04-x01-y01"); book(_hist_Wplus_MuAbseta, "d05-x01-y01"); book(_hist_Wminus_MuAbseta, "d06-x01-y01"); } void analyze(const Event& event) { // Get the reconstructed W const WFinder& wfinder_mu = applyProjection(event, "WFinder_mu"); if (wfinder_mu.bosons().size() != 1) vetoEvent; // No Missing Energy or MT cut at generator level: const FourMomentum& lepton0 = wfinder_mu.constituentLeptons()[0].momentum(); double pt0 = lepton0.pT(); double eta0 = fabs( lepton0.eta() ); if ( (eta0 > 2.4) || (pt0 < 26.0*GeV) ) vetoEvent; int muID = wfinder_mu.constituentLeptons()[0].pid(); // D* selection: // OS = W boson and D* Meson have Opposite (charge) Signs // SS = W Boson and D* Meson have Same (charge) Signs // Associated W+c only has OS contributions, // W+ccbar (ccbar from gluon splitting) has equal probability to be OS or SS // OS-SS to remove the gluon splitting background const UnstableParticles& dst = applyProjection(event, "Dstar"); for (auto p: dst.particles()) { if (muID == -13 && p.pid() == -413) { // OS _hist_Wplus_MuAbseta->fill(eta0); _hist_WplusMinus_MuAbseta->fill(eta0); } else if (muID == 13 && p.pid() == 413) { // OS _hist_Wminus_MuAbseta->fill(eta0); _hist_WplusMinus_MuAbseta->fill(eta0); } else if (muID == -13 && p.pid() == 413) { // SS _hist_Wplus_MuAbseta->fill(eta0*-1); _hist_WplusMinus_MuAbseta->fill(eta0*-1); } else if (muID == 13 && p.pid() == -413) { // SS _hist_Wminus_MuAbseta->fill(eta0*-1); _hist_WplusMinus_MuAbseta->fill(eta0*-1); } } } void finalize() { scale(_hist_Wplus_MuAbseta, crossSection()/picobarn/sumOfWeights()); scale(_hist_Wminus_MuAbseta, crossSection()/picobarn/sumOfWeights()); scale(_hist_WplusMinus_MuAbseta, crossSection()/picobarn/sumOfWeights()); } Histo1DPtr _hist_Wplus_MuAbseta; Histo1DPtr _hist_Wminus_MuAbseta; Histo1DPtr _hist_WplusMinus_MuAbseta; }; DECLARE_RIVET_PLUGIN(CMS_2019_I1705068); }