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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Xi_c' spectrum
class BABAR_2007_I722622 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I722622);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(),"UFS");
// Book histograms
book(_h_p_0,3,1,2);
book(_h_p_p,3,1,1);
book(_h_ctheta,4,1,1);
book(_b_p,1,1,1);
book(_b_0,1,1,2);
book(_r_p,2,1,1);
book(_r_0,2,1,2);
book(_ups,"/TMP/ups");
}
void findChildren(Particle parent, unsigned int & nStable,
Particles &Xi, unsigned int &nPi) {
for(const Particle & p : parent.children()) {
if(p.abspid()==PID::PIPLUS) {
++nPi;
++nStable;
}
else if(p.abspid()==PID::XIMINUS) {
Xi.push_back(p);
++nStable;
}
else if(!p.children().empty()) {
findChildren(p,nStable,Xi,nPi);
}
else {
++nStable;
}
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const int id0 = 4312, idp = 4322;
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
bool ups = !ufs.particles(Cuts::pid==300553).empty();
if(ups) _ups->fill();
for (const Particle& p : ufs.particles(Cuts::abspid==idp or Cuts::abspid==id0)) {
int idXic=4232;
if(p.abspid()==idp) {
_h_p_p->fill(p.momentum().p3().mod());
}
else {
_h_p_0->fill(p.momentum().p3().mod());
idXic=4132;
}
// first find the Xi_c in the decay
if(p.children().size()!=2) continue;
int sign=p.pid()/p.abspid();
Particle Xi_c;
if(p.children()[0].pid()==sign*idXic &&
p.children()[1].pid()==22) {
Xi_c = p.children()[0];
}
else if(p.children()[1].pid()==sign*idXic &&
p.children()[0].pid()==22) {
Xi_c = p.children()[1];
}
else
continue;
// and the children of the Xi_c
Particles Xi;
unsigned int nStable(0),nPi(0);
findChildren(Xi_c,nStable,Xi,nPi);
if(Xi.size()!=1) continue;
if( !(p.abspid()==idp && nPi==2 && nStable==3) &&
!(p.abspid()==id0 && nPi==1 && nStable==2) )
continue;
if(p.abspid()==idp) {
if(ups)
_b_p->fill(0.5);
else
_r_p->fill(0.5);
}
else {
if(ups)
_b_0->fill(0.5);
else
_r_0->fill(0.5);
idXic=4132;
}
// boost to Xi'_c rest frame
LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
FourMomentum pXic = boost1.transform(Xi_c.momentum());
FourMomentum pXi = boost1.transform(Xi[0].momentum());
// then to Xi_c rest frame
LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pXic.betaVec());
Vector3 axis = pXic.p3().unit();
FourMomentum pp = boost2.transform(pXi);
// calculate angle
double cTheta = pp.p3().unit().dot(axis);
_h_ctheta->fill(cTheta);
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_p_0 );
normalize(_h_p_p );
normalize(_h_ctheta);
if(_ups->effNumEntries()!=0) {
scale(_b_p,0.5/ *_ups);
scale(_b_0,0.5/ *_ups);
}
scale(_r_p,crossSection()/sumOfWeights()/femtobarn);
scale(_r_0,crossSection()/sumOfWeights()/femtobarn);
}
///@}
/// @name Histograms
///@{
Histo1DPtr _h_p_0,_h_p_p,_h_ctheta;
Histo1DPtr _b_p,_b_0;
Histo1DPtr _r_p,_r_0;
CounterPtr _ups;
///@}
};
RIVET_DECLARE_PLUGIN(BABAR_2007_I722622);
}
|