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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Add a short analysis description here
class OPAL_1996_I428493 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1996_I428493);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
// // Initialise and register projections
declare(ChargedFinalState(), "FS");
declare(UnstableParticles(), "UFS");
// Book histograms
book(_h_ctheta1, 3,1,1);
book(_h_ctheta2, "/TMP/ctheta",20,-1.,1.);
book(_c_hadron , "/TMP/chadron");
book(_c_bStar , "/TMP/cbStar ");
book(_c_B , "/TMP/cB ");
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// First, veto on leptonic events by requiring at least 4 charged FS particles
const FinalState& fs = apply<FinalState>(event, "FS");
const size_t numParticles = fs.particles().size();
// Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
if (numParticles < 2) {
MSG_DEBUG("Failed leptonic event cut");
vetoEvent;
}
MSG_DEBUG("Passed leptonic event cut");
_c_hadron->fill();
// loop over the particles
for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==513 or Cuts::abspid==523 or
Cuts::abspid==511 or Cuts::abspid==521)) {
int sign = p.pid()/p.abspid();
// count number of Bs not from mixing or B*
if(p.abspid()==511 || p.abspid()==521) {
if(p.parents()[0].abspid()==p.abspid()) continue;
if(p.parents()[0].abspid()==513 || p.parents()[0].abspid()==523) continue;
_c_B->fill();
}
// B*
else {
_c_bStar->fill();
Particle decay;
if(p.children().size()!=2) continue;
int mid = p.abspid()-2;
if(p.children()[0].pid()==sign*mid &&
p.children()[1].pid()==22) {
decay = p.children()[1];
}
else if(p.children()[1].pid()==sign*mid &&
p.children()[0].pid()==22) {
decay = p.children()[0];
}
else
continue;
LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
Vector3 e1z = p.p3().unit();
FourMomentum pp = boost.transform(decay.momentum());
Vector3 axis1 = boost.transform(decay.momentum()).p3().unit();
double ctheta = e1z.dot(axis1);
_h_ctheta1->fill(ctheta);
_h_ctheta2->fill(ctheta);
}
}
}
pair<double,double> calcRho(Histo1DPtr hist) {
if(hist->numEntries()==0.) return make_pair(0.,0.);
double sum1(0.),sum2(0.);
for (auto bin : hist->bins() ) {
double Oi = bin.area();
if(Oi==0.) continue;
double ai = 0.125*( -bin.xMin()*(3.+sqr(bin.xMin())) + bin.xMax()*(3.+sqr(bin.xMax())));
double bi = 0.375*( -bin.xMin()*(1.-sqr(bin.xMin())) + bin.xMax()*(1.-sqr(bin.xMax())));
double Ei = bin.areaErr();
sum1 += sqr(bi/Ei);
sum2 += bi/sqr(Ei)*(Oi-ai);
}
return make_pair(sum2/sum1,sqrt(1./sum1));
}
/// Normalise histograms etc., after the run
void finalize() {
// polarization
scale(_h_ctheta1,1./_c_hadron->val());
normalize(_h_ctheta2);
pair<double,double> rho = calcRho(_h_ctheta2);
Scatter2DPtr h_rho;
book(h_rho,2,1,1);
h_rho->addPoint(0.5, rho.first, make_pair(0.5,0.5),
make_pair(rho.second,rho.second) );
Scatter2DPtr h1;
book(h1, 1,1,1);
Counter ctemp = *_c_bStar+*_c_B;
// no of B*/B+B*
double val = _c_bStar->val()/ctemp.val();
double err = val*sqrt(sqr(_c_bStar->err()/_c_bStar->val())+sqr(ctemp.err()/ctemp.val()));
h1->addPoint(0.5,val,make_pair(0.5,0.5),make_pair(err,err) );
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_ctheta1, _h_ctheta2;
CounterPtr _c_hadron,_c_bStar,_c_B;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(OPAL_1996_I428493);
}
|