Rivet analyses
Cross section for e+e− → π+π−3π0 and π+π−2π0η between threshold and 4.35 GeV
Experiment: BABAR (PEP-II)
Inspire ID: 1700745
Status: VALIDATED
Authors: - Peter Richardson
References: - arXiv: 1810.11962
Beams: e+ e-
Beam energies: (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2)GeV
Run details: - e+e- to hadrons
Measurement of the cross section for e+e− → π+π−3π0 and π+π−2π0η between threshold and 4.35 GeV. The cross sections for the π+π−η, ωπ0π0 and ωπ0η resonant contributions are also measured.
Source
code:BABAR_2018_I1700745.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief e+e- -> pi+pi- and 3pi0 or 2pi0eta
class BABAR_2018_I1700745 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2018_I1700745);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(FinalState(), "FS");
declare(UnstableParticles(), "UFS");
for (size_t ix = 0; ix < 5; ++ix) {
book(_sigma[ix], 1 + ix, 1, 1);
for (const string& en : _sigma[0].binning().edges<0>()) {
const double eval = std::stod(en) * GeV;
if (isCompatibleWithSqrtS(eval)) {
_sqs = en;
break;
}
}
}
if (_sqs.empty() && isCompatibleWithSqrtS(1.075)) {
_sqs = "1.075";
}
else
raiseBeamErrorIf(_sqs.empty());
}
void findChildren(const Particle& p, map<long, int>& nRes, int& ncount) const {
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;
}
if (ntotal == 5 && nCount[211] == 1 && nCount[-211] == 1 && nCount[111] == 3) {
_sigma[0]->fill(_sqs);
}
const FinalState& ufs = apply<FinalState>(event, "UFS");
for (const Particle& p : ufs.particles()) {
if (p.children().empty()) continue;
if (p.pid() == 221 || p.pid() == 223) { // find eta/omegas
map<long, int> nRes = nCount;
int ncount = ntotal;
findChildren(p, nRes, ncount);
if (p.pid() == 221) { // eta
if (ncount == 2) { // 2 pi eta
bool matched = true;
for (const auto& val : nRes) {
if (abs(val.first) == 211) {
if (val.second != 1) {
matched = false;
break;
}
}
else if (val.second != 0) {
matched = false;
break;
}
}
if (matched) _sigma[1]->fill(_sqs);
}
else if (ncount == 4) { // 4 pi eta
bool matched = true;
for (const auto& val : nRes) {
if (abs(val.first) == 211) {
if (val.second != 1) {
matched = false;
break;
}
}
else if (abs(val.first) == 111) {
if (val.second != 2) {
matched = false;
break;
}
}
else if (val.second != 0) {
matched = false;
break;
}
}
if (matched) _sigma[3]->fill(_sqs);
}
for (const Particle& p2 : ufs.particles()) { // pi0 omega eta
if (p2.pid() != 223) continue;
map<long, int> nResB = nRes;
int ncountB = ncount;
findChildren(p2, nResB, ncountB);
if (ncountB != 1) continue;
bool matched = true;
for (const auto& val : nResB) {
if (abs(val.first) == 111) {
if (val.second != 1) {
matched = false;
break;
}
}
else if (val.second != 0) {
matched = false;
break;
}
}
if (matched) {
_sigma[4]->fill(_sqs);
break;
}
}
}
else {
if (ncount != 2) continue;
bool matched = true;
for (const auto& val : nRes) {
if (abs(val.first) == 111) {
if (val.second != 2) {
matched = false;
break;
}
}
else if (val.second != 0) {
matched = false;
break;
}
}
if (matched) _sigma[2]->fill(_sqs);
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
scale(_sigma, crossSection() / sumOfWeights() / nanobarn);
}
/// @}
/// @name Histograms
/// @{
BinnedHistoPtr<string> _sigma[5];
string _sqs = "";
/// @}
};
RIVET_DECLARE_PLUGIN(BABAR_2018_I1700745);
}