Rivet analyses referenceCMS_2015_I1385107Underlying event measurement with leading jets at $\sqrt{s} = 2.76$ \text{TeV}Experiment: CMS (LHC) Inspire ID: 1385107 Status: VALIDATED Authors:
Beams: p+ p+ Beam energies: (1380.0, 1380.0) GeV Run details:
A measurement of the underlying event (UE) activity in proton-proton collisions is performed using events with charged-particle jets produced in the central pseudorapidity region ($|\eta|^\text{jet} < 2$) and with transverse momentum $1 \leq p_T^\text{jet} < 100$ \text{GeV}. The analysis uses a data sample collected at a centre-of-mass energy of 2.76 \text{TeV} with the CMS experiment at the LHC. The UE activity is measured as a function of $p_T^\text{jet}$ in terms of the average multiplicity and scalar sum of transverse momenta of charged particles, with $|\eta| < 2$ and $p_T > 0.5$ \text{GeV}, in the azimuthal region transverse to the highest-$p_T$ jet direction. By further dividing the transverse region into two regions of smaller and larger activity, various components of the UE activity are separated. Source code: CMS_2015_I1385107.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/ChargedFinalState.hh"
5#include "Rivet/Projections/FastJets.hh"
6
7namespace Rivet {
8
9
10 /// CMS UE charged particles vs. leading jet at 2.76 TeV
11 class CMS_2015_I1385107 : public Analysis {
12 public:
13 /// Constructor
14 CMS_2015_I1385107() : Analysis("CMS_2015_I1385107"),
15 ETACUT(2.0),
16 AREATOT(2*ETACUT * 2*M_PI),
17 AREA3(AREATOT / 3.),
18 AREA6(AREATOT / 6.)
19 { }
20
21
22 /// Book histograms and initialise projections before the run
23 void init() {
24
25 const ChargedFinalState cfs(Cuts::abseta < 2 && Cuts::pT > 500*MeV);
26 declare(cfs, "CFS");
27
28 const ChargedFinalState cfsforjet(Cuts::abseta < 2.5 && Cuts::pT > 500*MeV);
29 const FastJets jetpro(cfsforjet, JetAlg::SISCONE, 0.5);
30 declare(jetpro, "Jets");
31
32 book(_h_Nch_TransAVE_vs_pT ,1, 1, 1); // Nch vs. pT_max (TransAVE)
33 book(_h_Sum_TransAVE_vs_pT ,2, 1, 1); // sum(pT) vs. pT_max (TransAVE)
34 book(_h_Nch_TransMAX_vs_pT ,3, 1, 1); // Nch vs. pT_max (TransMAX)
35 book(_h_Sum_TransMAX_vs_pT ,4, 1, 1); // sum(pT) vs. pT_max (TransMAX)
36 book(_h_Nch_TransMIN_vs_pT ,5, 1, 1); // Nch vs. pT_max (TransMIN)
37 book(_h_Sum_TransMIN_vs_pT ,6, 1, 1); // sum(pT) vs. pT_max (TransMIN)
38 book(_h_Nch_TransDIF_vs_pT ,7, 1, 1); // Nch vs. pT_max (TransDIF)
39 book(_h_Sum_TransDIF_vs_pT ,8, 1, 1); // sum(pT) vs. pT_max (TransDIF)
40 }
41
42
43 /// Local definition of a signed dphi, for use in differentating L and R trans regions
44 double signedDeltaPhi(double jetphi, double partphi) {
45 double delta = partphi - jetphi;
46 while (delta <= -PI) delta += 2 * PI;
47 while (delta > PI) delta -= 2 * PI;
48 return delta;
49 }
50
51 /// Perform the per-event analysis
52 void analyze(const Event& event) {
53
54 // Find the lead jet, applying a restriction that the jets must be within |eta| < 2.
55 FourMomentum p_lead;
56 for (const Jet& j : apply<FastJets>(event, "Jets").jetsByPt(Cuts::abseta < 2.0 && Cuts::pT > 1*GeV)) {
57 p_lead = j.momentum();
58 break;
59 }
60 if (p_lead.isZero()) vetoEvent;
61 const double phi_lead = p_lead.phi();
62 const double pT_lead = p_lead.pT();
63
64 // Loop on charged particles and separate Left and Right transverse regions
65 Particles particles = apply<ChargedFinalState>(event, "CFS").particlesByPt();
66 int nch_TransLeft = 0, nch_TransRight = 0;
67 double ptSum_TransLeft = 0., ptSum_TransRight = 0.;
68 for (const Particle& p : particles) {
69 const double dphi = signedDeltaPhi(phi_lead, p.momentum().phi());
70 if (!inRange(fabs(dphi), PI/3, 2*PI/3.)) continue; //< only fill trans regions
71 if (dphi < 0) { // Transverse Right region
72 nch_TransRight += 1;
73 ptSum_TransRight += p.pT() / GeV;
74 } else if (dphi > 0) { // Transverse Left region
75 nch_TransLeft += 1;
76 ptSum_TransLeft += p.pT() / GeV;
77 }
78 }
79
80 // Translate to min and max (+sum and diff) Transverse regions
81 const int nch_TransMIN = std::min(nch_TransLeft, nch_TransRight);
82 const int nch_TransMAX = std::max(nch_TransLeft, nch_TransRight);
83 const int nch_TransSUM = nch_TransMAX + nch_TransMIN;
84 const int nch_TransDIF = nch_TransMAX - nch_TransMIN;
85 //
86 const double ptSum_TransMIN = std::min(ptSum_TransLeft, ptSum_TransRight);
87 const double ptSum_TransMAX = std::max(ptSum_TransLeft, ptSum_TransRight);
88 const double ptSum_TransSUM = ptSum_TransMAX + ptSum_TransMIN;
89 const double ptSum_TransDIF = ptSum_TransMAX - ptSum_TransMIN;
90
91 // Fill profiles
92 _h_Nch_TransMIN_vs_pT->fill(pT_lead/GeV, 1/AREA6 * nch_TransMIN);
93 _h_Sum_TransMIN_vs_pT->fill(pT_lead/GeV, 1/AREA6 * ptSum_TransMIN);
94 //
95 _h_Nch_TransMAX_vs_pT->fill(pT_lead/GeV, 1/AREA6 * nch_TransMAX);
96 _h_Sum_TransMAX_vs_pT->fill(pT_lead/GeV, 1/AREA6 * ptSum_TransMAX);
97 //
98 _h_Nch_TransAVE_vs_pT->fill(pT_lead/GeV, 1/AREA3 * nch_TransSUM);
99 _h_Sum_TransAVE_vs_pT->fill(pT_lead/GeV, 1/AREA3 * ptSum_TransSUM);
100 //
101 _h_Nch_TransDIF_vs_pT->fill(pT_lead/GeV, 1/AREA6 * nch_TransDIF);
102 _h_Sum_TransDIF_vs_pT->fill(pT_lead/GeV, 1/AREA6 * ptSum_TransDIF);
103 }
104
105
106 private:
107
108 // Data members like post-cuts event weight counters go here
109 const double ETACUT, AREATOT, AREA3, AREA6;
110
111 /// Histograms
112 Profile1DPtr _h_Nch_TransAVE_vs_pT, _h_Sum_TransAVE_vs_pT;
113 Profile1DPtr _h_Nch_TransDIF_vs_pT, _h_Sum_TransDIF_vs_pT;
114 Profile1DPtr _h_Nch_TransMIN_vs_pT, _h_Sum_TransMIN_vs_pT;
115 Profile1DPtr _h_Nch_TransMAX_vs_pT, _h_Sum_TransMAX_vs_pT;
116
117 };
118
119
120 RIVET_DECLARE_PLUGIN(CMS_2015_I1385107);
121
122}
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