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118 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief e+e- > psi(2S) pi+pi-
class BESIII_2021_I1933191 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1933191);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
declare(FinalState(), "FS");
declare(UnstableParticles(), "UFS");
book(_nPsi2s, "TMP/psi2s");
}
void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
for (const Particle &child : p.children()) {
if(child.children().empty()) {
--nRes[child.pid()];
--ncount;
}
else
findChildren(child,nRes,ncount);
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const FinalState& fs = apply<FinalState>(event, "FS");
map<long,int> nCount;
int ntotal(0);
for (const Particle& p : fs.particles()) {
nCount[p.pid()] += 1;
++ntotal;
}
const FinalState& ufs = apply<FinalState>(event, "UFS");
for (const Particle& p : ufs.particles()) {
if(p.children().empty()) continue;
// find the psi(2S)
if(p.pid()==100443) {
map<long,int> nRes = nCount;
int ncount = ntotal;
findChildren(p,nRes,ncount);
// omega pi+pi-
if(ncount!=2) continue;
bool matched = true;
for(auto const & val : nRes) {
if(abs(val.first)==211) {
if(val.second !=1) {
matched = false;
break;
}
}
else if(val.second!=0) {
matched = false;
break;
}
}
if(matched) {
_nPsi2s->fill();
break;
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
double sigma = _nPsi2s->val();
double error = _nPsi2s->err();
sigma *= crossSection()/ sumOfWeights() /picobarn;
error *= crossSection()/ sumOfWeights() /picobarn;
Scatter2D temphisto(refData(1, 1, 3));
Scatter2DPtr mult;
book(mult, 1, 1, 3);
for (size_t b = 0; b < temphisto.numPoints(); b++) {
const double x = temphisto.point(b).x();
pair<double,double> ex = temphisto.point(b).xErrs();
pair<double,double> ex2 = ex;
if(ex2.first ==0.) ex2. first=0.0001;
if(ex2.second==0.) ex2.second=0.0001;
if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
mult->addPoint(x, sigma, ex, make_pair(error,error));
}
else {
mult->addPoint(x, 0., ex, make_pair(0.,.0));
}
}
}
///@}
/// @name Histograms
///@{
CounterPtr _nPsi2s;
///@}
};
RIVET_DECLARE_PLUGIN(BESIII_2021_I1933191);
}
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