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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/Thrust.hh"
namespace Rivet {
/// @brief p pbar correlations
class DELPHI_2000_I531568 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_2000_I531568);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
const ChargedFinalState cfs;
declare(cfs ,"CFS" );
declare(Thrust(cfs),"Thrust");
// book histos
book(_h_pMp,"_n_pMp",8,0.,1.);
book(_h_sum,"_n_sum",8,0.,1.);
}
void findPP(unsigned int mode, const Vector3 & axis, const Particles & part,
unsigned int & pp, double & dy) {
pp=0;
dy=1e30;
map<double,Particle> rapOrdered;
for(const Particle & p : part) {
const double mom = dot(axis, p.momentum().p3());
const double energy = p.E();
const double rap = 0.5 * std::log((energy + mom) / (energy - mom));
if(mode==0) {
if(rap>0.) rapOrdered[rap] = p;
}
else {
if(rap<=0.) rapOrdered[rap] = p;
}
}
map<double,Particle>::const_iterator ii[2]={rapOrdered.end(),rapOrdered.end()};
// map<double,Particle>::const_iterator it,i,im;
for(map<double,Particle>::const_iterator it=rapOrdered.begin();it!=rapOrdered.end();++it) {
if(it->second.abspid()==PID::PROTON) {
if(ii[0]!=rapOrdered.end())
ii[1]=it;
else
ii[0]=it;
}
}
// number of particles between the proton and antiproton
int rank = std::distance(ii[0],ii[1]);
if(rank>4) return;
// protom/antiproton next to each other, distance to nearest meson near them
if(rank==1) {
map<double,Particle>::const_iterator im=ii[0];--ii[0];
map<double,Particle>::const_iterator ip=ii[1];++ii[1];
if(ii[0]!=rapOrdered.begin()) {
pp=1;
dy = min(2./3.*abs(im->first-ii[0]->first),dy);
}
if(ip!=rapOrdered.end()) {
pp=1;
dy = min(2./3.*abs(ip->first-ii[1]->first),dy);
}
}
else {
double ycent = 0.5*(ii[0]->first+ii[1]->first);
double ymin=1e30;
map<double,Particle>::const_iterator im=rapOrdered.end();
map<double,Particle>::const_iterator it=ii[0];++it;
for(;it!=ii[1];++it) {
double test = abs(ycent-it->first);
if(test<ymin) {
im=it;
ymin=test;
}
}
pp=2;
dy = min(abs(ii[0]->first-im->first),abs(ii[1]->first-im->first));
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const Thrust thrust = apply<Thrust>(event,"Thrust");
Vector3 axis = thrust.thrustAxis();
const ChargedFinalState cfs = apply<ChargedFinalState>(event,"CFS");
unsigned int np[2]={0,0}, npbar[2]={0,0};
for(const Particle & p : cfs.particles()) {
const double mom = dot(axis, p.momentum().p3());
const double energy = p.E();
const double rap = 0.5 * std::log((energy + mom) / (energy - mom));
if(p.abspid()==PID::PROTON) {
unsigned int irap = rap>0 ? 0 : 1;
if(p.pid()>0) ++np [irap];
else ++npbar[irap];
}
}
if(np[0]==1 && npbar[0]==1) {
unsigned int pp = 0;
double dy(1e30);
findPP(0,axis,cfs.particles(),pp,dy);
if(pp==1) {
_h_sum->fill(dy);
}
else if(pp==2) {
_h_sum->fill(dy);
_h_pMp->fill(dy);
}
}
if(np[1]==1 && npbar[1]==1) {
unsigned int pp = 0;
double dy(1e30);
findPP(1,axis,cfs.particles(),pp,dy);
if(pp==1) {
_h_sum->fill(dy);
}
else if(pp==2) {
_h_sum->fill(dy);
_h_pMp->fill(dy);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
Scatter2DPtr h_r;
book(h_r,1,1,1);
divide(_h_pMp,_h_sum,h_r);
}
///@}
/// @name Histograms
///@{
Histo1DPtr _h_sum,_h_pMp;
///@}
};
RIVET_DECLARE_PLUGIN(DELPHI_2000_I531568);
}
|