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Rivet analyses reference
BABAR_2021_I1938254
Cross sections for $e^+e^-\to\pi^+\pi^-4\pi^0$ and $e^+e^-\to\pi^+\pi^-3\pi^0\eta$ between threshold and 4.5 GeV
Experiment: BABAR (PEP-II)
Inspire ID: 1938254
Status: VALIDATED
Authors:
References:
Beams: e+ e-
Beam energies: ANY
Run details:
Cross sections for $e^+e^-\to\pi^+\pi^-4\pi^0$ and $e^+e^-\to\pi^+\pi^-3\pi^0\eta$ between threshold and 4.5 GeV measured by BaBar using radiative return. The contributions of the $\eta\pi^+\pi^-\pi^0$, $\eta\omega$, $\omega\pi^0\pi^0\pi^0$ intermediate states are also measured. Useful to compare hadronization and other non-perturbative models at low energies between 1.4 and 4.5 GeV.
Source code:
BABAR_2021_I1938254.cc
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174 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief e+e- > pi+pi-4pi0 and pi+pi-3pi0 eta
class BABAR_2021_I1938254 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2021_I1938254);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(FinalState(), "FS");
declare(UnstableParticles(), "UFS");
// Histograms
for(unsigned int ix=0;ix<5;++ix) {
book(_num[ix],"TMP/num_"+to_string(ix));
}
}
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);
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
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;
}
// stable final state
if(nCount[211]==1 && nCount[-211]==1 && nCount[111]==4)
_num[0]->fill();
// intermediate states
const FinalState& ufs = apply<FinalState>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::pid==221 || Cuts::pid==223)) {
map<long,int> nRes = nCount;
int ncount = ntotal;
findChildren(p,nRes,ncount);
// eta +X
int idOther;
if(p.pid()==221) {
idOther=223;
bool matched = true;
for(auto const & val : nRes) {
if(abs(val.first)==211 || val.first==-211 ) {
if(val.second !=1) {
matched = false;
break;
}
}
else if(val.first==111) {
// 1 or 3 pi0
if(val.second !=3 && val.second != 1) {
matched = false;
break;
}
}
else if(val.second!=0) {
matched = false;
break;
}
}
if(matched) {
if(nRes[111]==1)
_num[1]->fill();
else
_num[4]->fill();
}
}
// omega+X
else {
idOther=221;
// omega+ 3pi0
bool matched = true;
for(auto const & val : nRes) {
if(abs(val.first)==111) {
if(val.second !=3) {
matched = false;
break;
}
}
else if(val.second!=0) {
matched = false;
break;
}
}
if(matched) {
_num[3]->fill();
}
}
for (const Particle& p2 : ufs.particles(Cuts::pid==idOther)) {
map<long,int> nResB = nRes;
int ncountB = ncount;
findChildren(p2,nResB,ncountB);
if(ncountB!=0) continue;
bool matched2 = true;
for(auto const & val : nResB) {
if(val.second!=0) {
matched2 = false;
break;
}
}
if(matched2) {
_num[2]->fill();
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
double fact = crossSection()/nanobarn/sumOfWeights();
for(unsigned int ix=0;ix<5;++ix) {
double sigma = _num[ix]->val()*fact;
double error = _num[ix]->err()*fact;
Scatter2D temphisto(refData(1+ix, 1, 1));
Scatter2DPtr mult;
book(mult, 1+ix, 1, 1);
for (size_t b = 0; b < temphisto.numPoints(); b++) {
const double x = temphisto.point(b).x();
pair<double,double> ex = temphisto.point(b).xErrs();
pair<double,double> ex2 = ex;
if(ex2.first ==0.) ex2. first=0.0001;
if(ex2.second==0.) ex2.second=0.0001;
if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
mult->addPoint(x, sigma, ex, make_pair(error,error));
}
else {
mult->addPoint(x, 0., ex, make_pair(0.,.0));
}
}
}
}
///@}
/// @name Histograms
///@{
CounterPtr _num[5];
///@}
};
RIVET_DECLARE_PLUGIN(BABAR_2021_I1938254);
}
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