Rivet analyses referenceBESIII_2017_I1509241Cross section for $e^+e^-\to p \bar{p} \pi^0$ at energies between 4.008 and 4.600 GeVExperiment: BESIII (BEPC) Inspire ID: 1509241 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Cross section for $e^+e^-\to p \bar{p} \pi^0$ at energies between 4.008 and 4.600 GeV measured by the BESIII collaboration. Source code: BESIII_2017_I1509241.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief e+e- -> p pbar pi0
9 class BESIII_2017_I1509241 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2017_I1509241);
14
15
16 /// @name Analysis methods
17 //@{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24
25 // Book histograms
26 book(_nproton, "TMP/proton");
27
28 }
29
30
31 /// Perform the per-event analysis
32 void analyze(const Event& event) {
33 const FinalState& fs = apply<FinalState>(event, "FS");
34 if(fs.particles().size()!=3) vetoEvent;
35 for (const Particle& p : fs.particles()) {
36 if(abs(p.pid())!=PID::PROTON&& p.pid()==PID::PI0) vetoEvent;
37 }
38 _nproton->fill();
39 }
40
41
42 /// Normalise histograms etc., after the run
43 void finalize() {
44 double sigma = _nproton->val();
45 double error = _nproton->err();
46 sigma *= crossSection()/ sumOfWeights() /picobarn;
47 error *= crossSection()/ sumOfWeights() /picobarn;
48 Scatter2D temphisto(refData(1, 1, 1));
49 Scatter2DPtr mult;
50 book(mult, 1, 1, 1);
51 for (size_t b = 0; b < temphisto.numPoints(); b++) {
52 const double x = temphisto.point(b).x();
53 pair<double,double> ex = temphisto.point(b).xErrs();
54 pair<double,double> ex2 = ex;
55 if(ex2.first ==0.) ex2. first=0.0001;
56 if(ex2.second==0.) ex2.second=0.0001;
57 if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
58 mult->addPoint(x, sigma, ex, make_pair(error,error));
59 }
60 else {
61 mult->addPoint(x, 0., ex, make_pair(0.,.0));
62 }
63 }
64 }
65
66 //@}
67
68
69 /// @name Histograms
70 //@{
71 CounterPtr _nproton;
72 //@}
73
74
75 };
76
77
78 RIVET_DECLARE_PLUGIN(BESIII_2017_I1509241);
79
80}
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