Rivet analyses referenceCMS_2019_I1705068Measurement of associated production of a W boson and a charm quark in proton-proton collisions at 13 TeVExperiment: CMS (LHC) Inspire ID: 1705068 Status: VALIDATED Authors:
Beam energies: (6500.0, 6500.0) GeV Run details:
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// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/FastJets.hh"
5#include "Rivet/Projections/UnstableParticles.hh"
6#include "Rivet/Projections/LeptonFinder.hh"
7#include "Rivet/Projections/MissingMomentum.hh"
8
9namespace Rivet {
10
11
12 /// W + charm quark in proton-proton collisions at 13 TeV
13 class CMS_2019_I1705068 : public Analysis {
14 public:
15
16 /// Constructor
17 RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2019_I1705068);
18
19
20 /// Initialise analyis
21 void init() {
22
23 // Projections
24 declare(MissingMom(), "MET");
25 LeptonFinder lf(0.1, Cuts::abseta < 2.4 && Cuts::abspid == PID::MUON);
26 declare(lf, "Leptons");
27
28 UnstableParticles dst(Cuts::pT > 5*GeV && Cuts::abseta < 2.4);
29 declare(dst, "Dstar");
30
31 // Particle-Level histograms from the paper:
32 book(_hist_WplusMinus_MuAbseta, "d04-x01-y01");
33 book(_hist_Wplus_MuAbseta, "d05-x01-y01");
34 book(_hist_Wminus_MuAbseta, "d06-x01-y01");
35 }
36
37
38 void analyze(const Event& event) {
39
40 // Identify the closest-matching mu+MET to m == mW
41 const P4& pmiss = apply<MissingMom>(event, "MET").missingMom();
42 const Particles& mus = apply<LeptonFinder>(event, "Leptons").particles();
43 const Particles mus_mtfilt = select(mus, [&](const Particle& m){ return mT(m, pmiss) > 0*GeV; });
44 const int imfound = closestMatchIndex(mus_mtfilt, pmiss, Kin::mass, 80.4*GeV);
45
46 // No MET or MT cut at generator level
47 if (imfound < 0) vetoEvent;
48 const Particle& lepton0 = mus_mtfilt[imfound];
49 const double pt0 = lepton0.pT();
50 const double eta0 = lepton0.abseta();
51 const int muID = lepton0.pid();
52 if (eta0 > 2.4 || pt0 < 26*GeV) vetoEvent;
53
54 // D* selection:
55 // OS = W boson and D* Meson have Opposite (charge) Signs
56 // SS = W Boson and D* Meson have Same (charge) Signs
57 // Associated W+c only has OS contributions,
58 // W+ccbar (ccbar from gluon splitting) has equal probability to be OS or SS
59 // OS-SS to remove the gluon splitting background
60
61 const UnstableParticles& dst = apply<UnstableParticles>(event, "Dstar");
62 for (const Particle& p : dst.particles()) {
63 if (muID == -13 && p.pid() == -413) { // OS
64 _hist_Wplus_MuAbseta->fill(eta0);
65 _hist_WplusMinus_MuAbseta->fill(eta0);
66 }
67 else if (muID == 13 && p.pid() == 413) { // OS
68 _hist_Wminus_MuAbseta->fill(eta0);
69 _hist_WplusMinus_MuAbseta->fill(eta0);
70 }
71 else if (muID == -13 && p.pid() == 413) { // SS
72 _hist_Wplus_MuAbseta->fill(eta0*-1);
73 _hist_WplusMinus_MuAbseta->fill(eta0*-1);
74 }
75 else if (muID == 13 && p.pid() == -413) { // SS
76 _hist_Wminus_MuAbseta->fill(eta0*-1);
77 _hist_WplusMinus_MuAbseta->fill(eta0*-1);
78 }
79 }
80
81 }
82
83
84 void finalize() {
85 scale(_hist_Wplus_MuAbseta, crossSection()/picobarn/sumOfWeights());
86 scale(_hist_Wminus_MuAbseta, crossSection()/picobarn/sumOfWeights());
87 scale(_hist_WplusMinus_MuAbseta, crossSection()/picobarn/sumOfWeights());
88 }
89
90
91 Histo1DPtr _hist_Wplus_MuAbseta;
92 Histo1DPtr _hist_Wminus_MuAbseta;
93 Histo1DPtr _hist_WplusMinus_MuAbseta;
94
95 };
96
97
98 RIVET_DECLARE_PLUGIN(CMS_2019_I1705068);
99
100}
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