Rivet analyses referenceDM2_1990_I297706Cross section for $e^+e^-\to p\bar{p}$ and $\Lambda\bar{\Lambda}$ at 2.4 GeVExperiment: DM2 (DCI) Inspire ID: 297706 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to p\bar{p}$ and $\Lambda\bar{\Lambda}$ at 2.4 GeV. Source code: DM2_1990_I297706.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/UnstableParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief Add a short analysis description here
10 class DM2_1990_I297706 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(DM2_1990_I297706);
15
16
17 /// @name Analysis methods
18 //@{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24 declare(UnstableParticles(), "UFS");
25 book(_nProton, "/TMP/nProton" );
26 book(_nLambda, "/TMP/nLambda" );
27 }
28
29 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
30 for (const Particle &child : p.children()) {
31 if(child.children().empty()) {
32 nRes[child.pid()]-=1;
33 --ncount;
34 }
35 else
36 findChildren(child,nRes,ncount);
37 }
38 }
39
40 /// Perform the per-event analysis
41 void analyze(const Event& event) {
42 const FinalState& fs = apply<FinalState>(event, "FS");
43 // total hadronic and muonic cross sections
44 map<long,int> nCount;
45 int ntotal(0);
46 for (const Particle& p : fs.particles()) {
47 nCount[p.pid()] += 1;
48 ++ntotal;
49 }
50 if(ntotal==2 && nCount[2212]==1 && nCount[-2212]==1)
51 _nProton->fill();
52
53 // find the Lambdas
54 const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
55 for(unsigned int ix=0;ix<ufs.particles().size();++ix) {
56 const Particle& p1 = ufs.particles()[ix];
57 if(abs(p1.pid())!=3122) continue;
58 bool matched = false;
59 // check fs
60 bool fs = true;
61 for (const Particle & child : p1.children()) {
62 if(child.pid()==p1.pid()) {
63 fs = false;
64 break;
65 }
66 }
67 if(!fs) continue;
68 // find the children
69 map<long,int> nRes = nCount;
70 int ncount = ntotal;
71 findChildren(p1,nRes,ncount);
72 for(unsigned int iy=ix+1;iy<ufs.particles().size();++iy) {
73 const Particle& p2 = ufs.particles()[iy];
74 if(abs(p2.pid())!=3122) continue;
75 // check fs
76 bool fs = true;
77 for (const Particle & child : p2.children()) {
78 if(child.pid()==p2.pid()) {
79 fs = false;
80 break;
81 }
82 }
83 if(!fs) continue;
84 map<long,int> nRes2 = nRes;
85 int ncount2 = ncount;
86 findChildren(p2,nRes2,ncount2);
87 if(ncount2!=0) continue;
88 matched=true;
89 for(auto const & val : nRes2) {
90 if(val.second!=0) {
91 matched = false;
92 break;
93 }
94 }
95 if(matched) {
96 _nLambda->fill();
97 break;
98 }
99 }
100 if(matched) break;
101 }
102 }
103
104
105 /// Normalise histograms etc., after the run
106 void finalize() {
107 double fact = crossSection()/ sumOfWeights() /picobarn;
108 for(unsigned int ix=1;ix<3;++ix) {
109 double sigma,error;
110 if(ix==1) {
111 sigma = _nProton->val()*fact;
112 error = _nProton->err()*fact;
113 }
114 else {
115 sigma = _nLambda->val()*fact;
116 error = _nLambda->err()*fact;
117 }
118 Scatter2D temphisto(refData(ix, 1, 1));
119 Scatter2DPtr mult;
120 book(mult, ix, 1, 1);
121 for (size_t b = 0; b < temphisto.numPoints(); b++) {
122 const double x = temphisto.point(b).x();
123 pair<double,double> ex = temphisto.point(b).xErrs();
124 pair<double,double> ex2 = ex;
125 if(ex2.first ==0.) ex2. first=0.0001;
126 if(ex2.second==0.) ex2.second=0.0001;
127 if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
128 mult->addPoint(x, sigma, ex, make_pair(error,error));
129 }
130 else {
131 mult->addPoint(x, 0., ex, make_pair(0.,.0));
132 }
133 }
134 }
135 }
136 //@}
137
138 /// @name Histograms
139 //@{
140 CounterPtr _nProton,_nLambda;
141 //@}
142
143 };
144
145
146 // The hook for the plugin system
147 RIVET_DECLARE_PLUGIN(DM2_1990_I297706);
148
149
150}
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