Rivet analyses referenceCMS_2012_I1107658Measurement of the underlying event activity in the Drell-Yan process at a centre-of-mass energy of 7 TeVExperiment: CMS (LHC) Inspire ID: 1107658 Status: VALIDATED Authors:
Beam energies: (3500.0, 3500.0) GeV Run details:
A measurement of the underlying event activity using Drell-Yan events using muonic final state. The production of charged particles with pseudorapidity $|\eta| < 2$ and transverse momentum $p_\perp > 0.5\,\text{GeV}/c$ is studied in towards, transverse and away region w.r.t. to the direction of di-muon system. The UE activity is measured in terms of of a particle density and an energy density. The particle density is computed as the average number of primary charged particles per unit pseudorapidity and per unit azimuth. The energy density is expressed in terms of the average of the scalar sum of the transverse momenta of primary charged particles per unit pseudorapidity and azimuth. The ratio of the energy and particle density is also reported in 3 regions. UE activity is studied as a function of invariant mass of muon pair ($M_{\mu\mu}$) by limiting the ISR contribution by requiring transverse momentum of muon pair $p_\perp(\mu\mu) < 5\,\text{GeV}/c$. The $p_\perp(\mu\mu)$ dependence is studied for the events having $M_{\mu\mu}$ in window of 81--101 GeV/$c$. The normalized charged particle multiplicity and $p_\perp$ spectrum of the charged particles in three regions also been reported for events having $M_{\mu\mu}$ in window of 81--101 GeV/$c$. Multiplicity and $p_\perp$ spectra in the transverse region are also reported, for events having $p_\perp(\mu\mu) < 5\,\text{GeV}/c$. Source code: CMS_2012_I1107658.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/DileptonFinder.hh"
5#include "Rivet/Projections/FinalState.hh"
6#include "Rivet/Projections/ChargedFinalState.hh"
7#include "Rivet/Projections/VetoedFinalState.hh"
8
9namespace Rivet {
10
11
12 /// Underlying event activity in the Drell-Yan process at 7 TeV
13 class CMS_2012_I1107658 : public Analysis {
14 public:
15
16 /// Constructor
17 RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2012_I1107658);
18
19
20 /// Initialization
21 void init() {
22
23 /// @note Using a bare muon Z (but with a clustering radius!?)
24 Cut cut = Cuts::abseta < 2.4 && Cuts::pT > 20*GeV;
25 DileptonFinder zfinder(91.2*GeV, 0.2, cut && Cuts::abspid == PID::MUON, Cuts::massIn(4*GeV, 140*GeV));
26 declare(zfinder, "DileptonFinder");
27
28 ChargedFinalState nonmuons(Cuts::abseta < 2 && Cuts::pT > 500*MeV && Cuts::abspid != PID::MUON);
29 declare(nonmuons, "nonmuons");
30
31 book(_h_Nchg_towards_pTmumu ,1, 1, 1);
32 book(_h_Nchg_transverse_pTmumu ,2, 1, 1);
33 book(_h_Nchg_away_pTmumu ,3, 1, 1);
34 book(_h_pTsum_towards_pTmumu ,4, 1, 1);
35 book(_h_pTsum_transverse_pTmumu ,5, 1, 1);
36 book(_h_pTsum_away_pTmumu ,6, 1, 1);
37 book(_h_avgpT_towards_pTmumu ,7, 1, 1);
38 book(_h_avgpT_transverse_pTmumu ,8, 1, 1);
39 book(_h_avgpT_away_pTmumu ,9, 1, 1);
40 book(_h_Nchg_towards_plus_transverse_Mmumu ,10, 1, 1);
41 book(_h_pTsum_towards_plus_transverse_Mmumu ,11, 1, 1);
42 book(_h_avgpT_towards_plus_transverse_Mmumu ,12, 1, 1);
43 book(_h_Nchg_towards_zmass_81_101 ,13, 1, 1);
44 book(_h_Nchg_transverse_zmass_81_101 ,14, 1, 1);
45 book(_h_Nchg_away_zmass_81_101 ,15, 1, 1);
46 book(_h_pT_towards_zmass_81_101 ,16, 1, 1);
47 book(_h_pT_transverse_zmass_81_101 ,17, 1, 1);
48 book(_h_pT_away_zmass_81_101 ,18, 1, 1);
49 book(_h_Nchg_transverse_zpt_5 ,19, 1, 1);
50 book(_h_pT_transverse_zpt_5 ,20, 1, 1);
51 }
52
53
54 /// Perform the per-event analysis
55 void analyze(const Event& event) {
56 const DileptonFinder& zfinder = apply<DileptonFinder>(event, "DileptonFinder");
57
58 if (zfinder.bosons().size() != 1) vetoEvent;
59
60 double Zpt = zfinder.bosons()[0].pT()/GeV;
61 double Zphi = zfinder.bosons()[0].phi();
62 double Zmass = zfinder.bosons()[0].mass()/GeV;
63
64 Particles particles = apply<VetoedFinalState>(event, "nonmuons").particles();
65
66 int nTowards = 0;
67 int nTransverse = 0;
68 int nAway = 0;
69 double ptSumTowards = 0;
70 double ptSumTransverse = 0;
71 double ptSumAway = 0;
72
73 for (const Particle& p : particles) {
74 double dphi = fabs(deltaPhi(Zphi, p.phi()));
75 double pT = p.pT();
76
77 if ( dphi < M_PI/3 ) {
78 nTowards++;
79 ptSumTowards += pT;
80 if (Zmass > 81. && Zmass < 101.) _h_pT_towards_zmass_81_101->fill(pT);
81 } else if ( dphi < 2.*M_PI/3 ) {
82 nTransverse++;
83 ptSumTransverse += pT;
84 if (Zmass > 81. && Zmass < 101.) _h_pT_transverse_zmass_81_101->fill(pT);
85 if (Zpt < 5.) _h_pT_transverse_zpt_5->fill(pT);
86 } else {
87 nAway++;
88 ptSumAway += pT;
89 if (Zmass > 81. && Zmass < 101.) _h_pT_away_zmass_81_101->fill(pT);
90 }
91
92 } // Loop over particles
93
94
95 const double area = 8./3.*M_PI;
96 if (Zmass > 81. && Zmass < 101.) {
97 _h_Nchg_towards_pTmumu-> fill(Zpt, 1./area * nTowards);
98 _h_Nchg_transverse_pTmumu-> fill(Zpt, 1./area * nTransverse);
99 _h_Nchg_away_pTmumu-> fill(Zpt, 1./area * nAway);
100 _h_pTsum_towards_pTmumu-> fill(Zpt, 1./area * ptSumTowards);
101 _h_pTsum_transverse_pTmumu-> fill(Zpt, 1./area * ptSumTransverse);
102 _h_pTsum_away_pTmumu-> fill(Zpt, 1./area * ptSumAway);
103 if (nTowards > 0) _h_avgpT_towards_pTmumu-> fill(Zpt, ptSumTowards/nTowards);
104 if (nTransverse > 0) _h_avgpT_transverse_pTmumu-> fill(Zpt, ptSumTransverse/nTransverse);
105 if (nAway > 0) _h_avgpT_away_pTmumu-> fill(Zpt, ptSumAway/nAway);
106 _h_Nchg_towards_zmass_81_101-> fill(nTowards);
107 _h_Nchg_transverse_zmass_81_101->fill(nTransverse);
108 _h_Nchg_away_zmass_81_101-> fill(nAway);
109 }
110
111 if (Zpt < 5.) {
112 _h_Nchg_towards_plus_transverse_Mmumu->fill(Zmass, (nTowards + nTransverse)/(2.*area));
113 _h_pTsum_towards_plus_transverse_Mmumu->fill(Zmass, (ptSumTowards + ptSumTransverse)/(2.*area));
114 if ((nTowards + nTransverse) > 0) _h_avgpT_towards_plus_transverse_Mmumu->fill(Zmass, (ptSumTowards + ptSumTransverse)/(nTowards + nTransverse));
115 _h_Nchg_transverse_zpt_5->fill(nTransverse);
116 }
117
118 }
119
120
121 /// Normalise histograms etc., after the run
122 void finalize() {
123 scale(_h_pT_towards_zmass_81_101, safediv(1, _h_Nchg_towards_zmass_81_101->integral(), 0));
124 scale(_h_pT_transverse_zmass_81_101, safediv(1, _h_Nchg_transverse_zmass_81_101->integral(), 0));
125 scale(_h_pT_away_zmass_81_101, safediv(1, _h_Nchg_away_zmass_81_101->integral(), 0));
126 scale(_h_pT_transverse_zpt_5, safediv(1, _h_Nchg_transverse_zpt_5->integral(), 0));
127 normalize(_h_Nchg_towards_zmass_81_101);
128 normalize(_h_Nchg_transverse_zmass_81_101);
129 normalize(_h_Nchg_away_zmass_81_101);
130 normalize(_h_Nchg_transverse_zpt_5);
131 }
132
133
134 private:
135
136
137 /// @name Histogram objects
138 /// @{
139 Profile1DPtr _h_Nchg_towards_pTmumu;
140 Profile1DPtr _h_Nchg_transverse_pTmumu;
141 Profile1DPtr _h_Nchg_away_pTmumu;
142 Profile1DPtr _h_pTsum_towards_pTmumu;
143 Profile1DPtr _h_pTsum_transverse_pTmumu;
144 Profile1DPtr _h_pTsum_away_pTmumu;
145 Profile1DPtr _h_avgpT_towards_pTmumu;
146 Profile1DPtr _h_avgpT_transverse_pTmumu;
147 Profile1DPtr _h_avgpT_away_pTmumu;
148 Profile1DPtr _h_Nchg_towards_plus_transverse_Mmumu;
149 Profile1DPtr _h_pTsum_towards_plus_transverse_Mmumu;
150 Profile1DPtr _h_avgpT_towards_plus_transverse_Mmumu;
151 Histo1DPtr _h_Nchg_towards_zmass_81_101;
152 Histo1DPtr _h_Nchg_transverse_zmass_81_101;
153 Histo1DPtr _h_Nchg_away_zmass_81_101;
154 Histo1DPtr _h_pT_towards_zmass_81_101;
155 Histo1DPtr _h_pT_transverse_zmass_81_101;
156 Histo1DPtr _h_pT_away_zmass_81_101;
157 Histo1DPtr _h_Nchg_transverse_zpt_5;
158 Histo1DPtr _h_pT_transverse_zpt_5;
159 /// @}
160
161 };
162
163
164 RIVET_DECLARE_PLUGIN(CMS_2012_I1107658);
165
166}
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