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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Tools/BinnedHistogram.hh"
namespace Rivet {
/// @brief D* helicity in e+e- at 10.5 GeV
class CLEO_1998_I467595 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1998_I467595);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(Beam(), "Beams");
declare(UnstableParticles(), "UFS");
// Book histograms
{Histo1DPtr temp; _h_ctheta.add(0.25,0.45,book(temp,5,1,1));}
{Histo1DPtr temp; _h_ctheta.add(0.45,0.55,book(temp,5,1,2));}
{Histo1DPtr temp; _h_ctheta.add(0.55,0.65,book(temp,5,1,3));}
{Histo1DPtr temp; _h_ctheta.add(0.65,0.75,book(temp,5,1,4));}
{Histo1DPtr temp; _h_ctheta.add(0.75,0.85,book(temp,5,1,5));}
{Histo1DPtr temp; _h_ctheta.add(0.85,1. ,book(temp,5,1,6));}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Get beams and average beam momentum
const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
const double Emax = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
const double Pmax = sqrt(sqr(Emax)-sqr(2.01026));
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::abspid==413)) {
if(p.children().size()!=2) continue;
int sign = p.pid()/413;
Particle D0;
if(p.children()[0].pid()==sign*421 && p.children()[1].pid()==sign*211) {
D0 = p.children()[0];
}
else if(p.children()[1].pid()==sign*421 && p.children()[0].pid()==sign*211) {
D0 = p.children()[1];
}
else
continue;
LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
double xp = (p.momentum().p3().mod()+p.momentum().t())/(Pmax+Emax);
Vector3 e1z = p.momentum().p3().unit();
Vector3 axis1 = boost.transform(D0.momentum()).p3().unit();
double ctheta = e1z.dot(axis1);
_h_ctheta.fill(xp,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 = 0.25*(bin.xMax()*(3.-sqr(bin.xMax())) - bin.xMin()*(3.-sqr(bin.xMin())));
double bi = 0.75*(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));
}
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() {
vector<double> x = {0.25,0.45,0.55,0.65,0.75,0.85,1.};
Scatter2DPtr h_alpha;
book(h_alpha,3,1,1);
Scatter2DPtr h_rho;
book(h_rho ,4,1,1);
for(unsigned int ix=0;ix<6;++ix) {
normalize(_h_ctheta.histos()[ix]);
pair<double,double> rho00 = calcRho(_h_ctheta.histos()[ix]);
h_rho->addPoint(0.5*(x[ix]+x[ix+1]), rho00.first, make_pair(0.5*(x[ix+1]-x[ix]),0.5*(x[ix+1]-x[ix])),
make_pair(rho00.second,rho00.second) );
pair<double,pair<double,double> > alpha = calcAlpha(_h_ctheta.histos()[ix]);
h_alpha->addPoint(0.5*(x[ix]+x[ix+1]), alpha.first, make_pair(0.5*(x[ix+1]-x[ix]),0.5*(x[ix+1]-x[ix])),
alpha.second);
}
}
//@}
/// @name Histograms
//@{
BinnedHistogram _h_ctheta;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(CLEO_1998_I467595);
}
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