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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Jpsi/psi2S baryon decay analysis
class BESIII_2016_I1422780 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2016_I1422780);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(Beam(), "Beams");
declare(UnstableParticles(), "UFS");
declare(FinalState(), "FS");
// Book histograms
if(isCompatibleWithSqrtS(3.1,1e-1)) {
book(_h_xi , 2, 1, 1);
book(_h_sigm, 2, 1, 2);
book(_h_sigp, 2, 1, 3);
}
else if (isCompatibleWithSqrtS(3.686, 1E-1)) {
book(_h_xi , 2, 1, 4);
book(_h_sigm, 2, 1, 5);
book(_h_sigp, 2, 1, 6);
}
}
void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
for( const Particle &child : p.children()) {
if(child.children().empty()) {
nRes[child.pid()]-=1;
--ncount;
}
else
findChildren(child,nRes,ncount);
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// get the axis, direction of incoming electron
const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
Vector3 axis;
if(beams.first.pid()>0)
axis = beams.first .momentum().p3().unit();
else
axis = beams.second.momentum().p3().unit();
// types of final state particles
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 UnstableParticles & ufs = apply<UnstableParticles>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::abspid==3312 or Cuts::abspid==3224 or Cuts::abspid==3114)) {
if(p.children().empty()) continue;
map<long,int> nRes=nCount;
int ncount = ntotal;
findChildren(p,nRes,ncount);
bool matched=false;
// check for antiparticle
for (const Particle& p2 : ufs.particles(Cuts::pid==-p.pid())) {
if(p2.children().empty()) continue;
map<long,int> nRes2=nRes;
int ncount2 = ncount;
findChildren(p2,nRes2,ncount2);
if(ncount2==0) {
matched = true;
for(auto const & val : nRes2) {
if(val.second!=0) {
matched = false;
break;
}
}
// fond baryon and antibaryon
if(matched) {
// calc cosine
double ctheta;
if(p.pid()>0)
ctheta = p .momentum().p3().unit().dot(axis);
else
ctheta = p2.momentum().p3().unit().dot(axis);
if(abs(p.pid())==3312)
_h_xi ->fill(ctheta);
else if(abs(p.pid())==3114)
_h_sigm->fill(ctheta);
else if(abs(p.pid())==3224)
_h_sigp->fill(ctheta);
break;
}
}
}
if(matched) break;
}
}
pair<double,pair<double,double> > calcAlpha(Histo1DPtr hist) {
if(hist->numEntries()==0.) return make_pair(0.,make_pair(0.,0.));
double d = 3./(pow(hist->xMax(),3)-pow(hist->xMin(),3));
double c = 3.*(hist->xMax()-hist->xMin())/(pow(hist->xMax(),3)-pow(hist->xMin(),3));
double sum1(0.),sum2(0.),sum3(0.),sum4(0.),sum5(0.);
for (auto bin : hist->bins() ) {
double Oi = bin.area();
if(Oi==0.) continue;
double a = d*(bin.xMax() - bin.xMin());
double b = d/3.*(pow(bin.xMax(),3) - pow(bin.xMin(),3));
double Ei = bin.areaErr();
sum1 += a*Oi/sqr(Ei);
sum2 += b*Oi/sqr(Ei);
sum3 += sqr(a)/sqr(Ei);
sum4 += sqr(b)/sqr(Ei);
sum5 += a*b/sqr(Ei);
}
// calculate alpha
double alpha = (-c*sum1 + sqr(c)*sum2 + sum3 - c*sum5)/(sum1 - c*sum2 + c*sum4 - sum5);
// and error
double cc = -pow((sum3 + sqr(c)*sum4 - 2*c*sum5),3);
double bb = -2*sqr(sum3 + sqr(c)*sum4 - 2*c*sum5)*(sum1 - c*sum2 + c*sum4 - sum5);
double aa = sqr(sum1 - c*sum2 + c*sum4 - sum5)*(-sum3 - sqr(c)*sum4 + sqr(sum1 - c*sum2 + c*sum4 - sum5) + 2*c*sum5);
double dis = sqr(bb)-4.*aa*cc;
if(dis>0.) {
dis = sqrt(dis);
return make_pair(alpha,make_pair(0.5*(-bb+dis)/aa,-0.5*(-bb-dis)/aa));
}
else {
return make_pair(alpha,make_pair(0.,0.));
}
}
/// Normalise histograms etc., after the run
void finalize() {
// find energy
int ioff=-1;
if(isCompatibleWithSqrtS(3.1,1e-1)) ioff=0;
else if (isCompatibleWithSqrtS(3.686, 1E-1)) ioff=1;
vector< pair<double,pair<double,double> > > alpha;
normalize(_h_xi,1.,false);
alpha.push_back(calcAlpha(_h_xi));
normalize(_h_sigm,1.,false);
alpha.push_back(calcAlpha(_h_sigm));
normalize(_h_sigp,1.,false);
alpha.push_back(calcAlpha(_h_sigp));
Scatter2DPtr _h_alpha;
book(_h_alpha,1,1,3);
for(unsigned int ix=0;ix<3;++ix)
_h_alpha->addPoint(1.+ix+3.*ioff, alpha[ix].first, make_pair(0.5,0.5),
make_pair(alpha[ix].second.first,alpha[ix].second.second) );
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_xi,_h_sigm,_h_sigp;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(BESIII_2016_I1422780);
}
|