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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
namespace Rivet {
/// @brief gamma gamma -> pi+pi-
class VENUS_1995_I392360 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(VENUS_1995_I392360);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Final state
declare(FinalState(),"FS");
// check CMS energy in range
if(sqrtS()<1.*GeV || sqrtS()>1.5*GeV)
throw Error("Invalid CMS energy for VENUS_1995_I392360");
// bin for the angle plots
int ibin = (sqrtS()-1.0)/0.05 + 2;
book(_h_cTheta,ibin,1,1);
book(_cPi, "/TMP/nPi");
_cmax = ibin>2 ? 0.6 : 0.4;
}
/// Perform the per-event analysis
void analyze(const Event& event) {
Particles part = applyProjection<FinalState>(event,"FS").particles();
if(part.size()!=2) vetoEvent;
double cTheta(0.);
bool foundP(false),foundM(false);
for(const Particle & p : part) {
if(p.pid()==PID::PIPLUS) {
foundP=true;
cTheta = abs(p.momentum().z()/p.momentum().p3().mod());
}
else if(p.pid()==PID::PIMINUS)
foundM=true;
}
if(!foundP || !foundM) vetoEvent;
if(cTheta<=_cmax) _cPi->fill();
if(_h_cTheta ) _h_cTheta ->fill(cTheta);
}
/// Normalise histograms etc., after the run
void finalize() {
double fact = crossSection()/nanobarn/sumOfWeights();
if(_h_cTheta ) scale(_h_cTheta ,fact);
double sigma = _cPi->val()*fact;
double error = _cPi->err()*fact;
Scatter2D temphisto(refData(1, 1, 1));
Scatter2DPtr mult;
book(mult, 1, 1, 1);
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(), 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
///@{
Histo1DPtr _h_cTheta;
CounterPtr _cPi;
double _cmax;
///@}
};
RIVET_DECLARE_PLUGIN(VENUS_1995_I392360);
}
|