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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/Beam.hh"
namespace Rivet {
/// @brief e+e- > e+e- eta'
class BABAR_2018_I1691222 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2018_I1691222);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(Beam(), "Beams");
declare(FinalState(),"FS");
declare(UnstableParticles(), "UFS");
// book the histograms
book(_h_etap,1,1,1);
}
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);
}
}
}
bool findScattered(Particle beam, double& q2) {
bool found = false;
Particle scat = beam;
while (!scat.children().empty()) {
found = false;
for (const Particle & p : scat.children()) {
if (p.pid()==scat.pid()) {
scat=p;
found=true;
break;
}
}
if (!found) break;
}
if (!found) return false;
q2 = -(beam.momentum() - scat.momentum()).mass2();
return true;
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// find scattered leptons and calc Q2
const Beam& beams = apply<Beam>(event, "Beams");
double q12 = -1, q22 = -1;
if (!findScattered(beams.beams().first, q12)) vetoEvent;
if (!findScattered(beams.beams().second, q22)) vetoEvent;
if(q22>q12) swap(q12,q22);
// check the final state
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;
}
// find the meson
const FinalState& ufs = apply<FinalState>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::pid==331)) {
if(p.children().empty()) continue;
map<long,int> nRes = nCount;
int ncount = ntotal;
findChildren(p,nRes,ncount);
bool matched = true;
for(auto const & val : nRes) {
if(abs(val.first)==11) {
if(val.second!=1) {
matched = false;
break;
}
}
else if(val.second!=0) {
matched = false;
break;
}
}
if (matched) {
// 2<Q2<10 for both photons bin
if(q12>2.&&q12<10.&&q22>2.&&q22<10.) {
_h_etap->fill(0,1./sqr(8.));
}
// 10<Q2<30 for both photons bin
else if(q12>10&&q12<30.&&q22>10.&&q22<30.)
_h_etap->fill(1,1./sqr(20.));
// 10<Q12<30 2<Q22<10
else if(q22>2.&&q22<10.&&q12>10.&&q12<30.)
_h_etap->fill(2,1./8./20./2.);
// 2<Q22<30 30<Q12<60
else if(q22>2.&&q22<30.&&q12>30.&&q12<60.)
_h_etap->fill(3,1./28./30./2.);
// 30<Q2<60 for both photons
else if(q22>30.&&q22<60.&&q12>30.&&q12<60.)
_h_etap->fill(4,1./sqr(30.));
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
scale(_h_etap, 1e4*crossSection()/femtobarn/sumW());
}
///@}
/// @name Histograms
///@{
Histo1DPtr _h_etap;
unsigned int _ncount=0;
///@}
};
RIVET_DECLARE_PLUGIN(BABAR_2018_I1691222);
}
|