Rivet analyses referenceBESIII_2020_I1837725Measurement of the cross section for $e^+e^-\to2p2\bar{p}$ for $E_{\text{CMS}}$ between 4 and 4.6 GeVExperiment: BESIII (BEPC) Inspire ID: 1837725 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to2p2\bar{p}$ for $E_{\text{CMS}}$ between 4 and 4.6 GeV by the BESIII collaboration. Source code: BESIII_2020_I1837725.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/FastJets.hh"
5#include "Rivet/Projections/DressedLeptons.hh"
6#include "Rivet/Projections/MissingMomentum.hh"
7#include "Rivet/Projections/PromptFinalState.hh"
8
9namespace Rivet {
10
11
12 /// @brief e+e- > 2p 2pbar
13 class BESIII_2020_I1837725 : public Analysis {
14 public:
15
16 /// Constructor
17 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1837725);
18
19
20 /// @name Analysis methods
21 ///@{
22
23 /// Book histograms and initialise projections before the run
24 void init() {
25
26 // Initialise and register projections
27 declare(FinalState(), "FS");
28
29 // Book histograms
30 book(_nproton, "TMP/proton");
31 }
32
33
34 /// Perform the per-event analysis
35 void analyze(const Event& event) {
36 const FinalState& fs = apply<FinalState>(event, "FS");
37 if(fs.particles().size()!=4) vetoEvent;
38 for (const Particle& p : fs.particles()) {
39 if(abs(p.pid())!=PID::PROTON) vetoEvent;
40 }
41 _nproton->fill();
42 }
43
44
45 /// Normalise histograms etc., after the run
46 void finalize() {
47 double sigma = _nproton->val();
48 double error = _nproton->err();
49 sigma *= crossSection()/ sumOfWeights() /femtobarn;
50 error *= crossSection()/ sumOfWeights() /femtobarn;
51 Scatter2D temphisto(refData(1, 1, 1));
52 Scatter2DPtr mult;
53 book(mult, 1, 1, 1);
54 for (size_t b = 0; b < temphisto.numPoints(); b++) {
55 const double x = temphisto.point(b).x();
56 pair<double,double> ex = temphisto.point(b).xErrs();
57 pair<double,double> ex2 = ex;
58 if(ex2.first ==0.) ex2. first=0.0001;
59 if(ex2.second==0.) ex2.second=0.0001;
60 if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
61 mult->addPoint(x, sigma, ex, make_pair(error,error));
62 }
63 else {
64 mult->addPoint(x, 0., ex, make_pair(0.,.0));
65 }
66 }
67 }
68
69 ///@}
70
71
72 /// @name Histograms
73 ///@{
74 CounterPtr _nproton;
75 ///@}
76
77
78 };
79
80
81 RIVET_DECLARE_PLUGIN(BESIII_2020_I1837725);
82
83}
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