Rivet analyses
γγ → K*0K̄*0 between 1.6 and 3.5 GeV
Experiment: ARGUS (DORIS)
Inspire ID: 248680
Status: VALIDATED
Authors: - Peter Richardson
References: - Eur.Phys.J.C 16 (2000) 435-444
Beams: 22 22
Beam energies: (0.8, 0.8); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (1.0, 1.0); (1.0, 1.0); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.2, 1.2); (1.2, 1.2); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.4, 1.4); (1.4, 1.4); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.6, 1.6); (1.6, 1.6); (1.7, 1.7)GeV
Run details: - gamma gamma to hadrons, K0S and pi0 mesons must be set stable
Measurement of the differential cross section for γγ → K*0K̄*0 for 1.6GeV < W < 3.5GeV. The cross section is measured as a function of the centre-of-mass energy of the photonic collision using the K+K−π+π− final state.
Source
code:ARGUS_1987_I248680.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief gamma gamma -> K*0K*0
class ARGUS_1987_I248680 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1987_I248680);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(FinalState(), "FS");
declare(UnstableParticles(), "UFS");
// book histos
for (size_t ih = 0; ih < 5; ++ih) {
book(_est[ih], 5, 1, ih + 1);
book(_xsec[ih], "_aux_xsec_" + toString(ih), _est[ih].binning().edges<0>());
}
for (double eVal : allowedEnergies()) {
const string en = toString(round(eVal / MeV));
if (isCompatibleWithSqrtS(eVal)) _sqs = en;
for (size_t ix = 0; ix < 9; ++ix) {
book(_nMeson[en + toString(ix)], "TMP/nMeson_" + en + "_" + toString(ix + 1));
}
}
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()] -= 1;
--ncount;
}
else {
findChildren(child, nRes, ncount);
}
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const FinalState& fs = apply<FinalState>(event, "FS");
// find the final-state particles
map<long, int> nCount;
int ntotal(0);
for (const Particle& p : fs.particles()) {
nCount[p.pid()] += 1;
++ntotal;
}
// find any K* mesons
int ires = -1;
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
Particles Kstar = ufs.particles(Cuts::abspid == 313);
for (size_t ix = 0; ix < Kstar.size(); ++ix) {
if (Kstar[ix].children().empty()) continue;
map<long, int> nRes = nCount;
int ncount = ntotal;
findChildren(Kstar[ix], nRes, ncount);
bool matched = false;
// K*K*
for (size_t iy = ix + 1; iy < Kstar.size(); ++iy) {
if (Kstar[iy].children().empty()) continue;
if (Kstar[ix].pid() != -Kstar[iy].pid()) continue;
map<long, int> nRes2 = nRes;
int ncount2 = ncount;
findChildren(Kstar[iy], nRes2, ncount2);
if (ncount2 != 0) continue;
matched = true;
for (const auto& val : nRes2) {
if (val.second != 0) {
matched = false;
break;
}
}
if (matched) {
break;
}
}
if (matched) {
_nMeson[_sqs + "1"s]->fill();
ires = 7;
break;
}
int sign = Kstar[ix].pid() / Kstar[ix].abspid();
// three body intermediate states
if (ncount == 2) {
// K*0 K- pi+ +ccd
matched = true;
for (const auto& val : nRes) {
if (val.first == sign * 211 || val.first == -sign * 321) {
if (val.second != 1) {
matched = false;
break;
}
}
else {
if (val.second != 0) {
matched = false;
break;
}
}
}
if (matched) {
_nMeson[_sqs + "2"s]->fill();
ires = 6;
break;
}
}
}
// look for phi modes
for (const Particle& p : ufs.particles(Cuts::pid == PID::PHI)) {
if (p.children().empty()) continue;
map<long, int> nRes = nCount;
int ncount = ntotal;
findChildren(p, nRes, ncount);
if (ncount == 2) {
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) {
ires = 8;
break;
}
}
}
// 4 meson modes
if (ntotal == 4 && nCount[PID::KPLUS] == 1 && nCount[PID::KMINUS] == 1 && nCount[PID::PIPLUS] == 1
&& nCount[PID::PIMINUS] == 1) {
_nMeson[_sqs + "0"s]->fill();
_nMeson[_sqs + "4"s]->fill();
_xsec[0]->fill(sqrtS() / GeV);
if (ires < 0) {
_nMeson[_sqs + "3"s]->fill();
_nMeson[_sqs + "5"s]->fill();
_xsec[1]->fill(sqrtS() / GeV);
}
else {
_nMeson[_sqs + toString(ires)]->fill();
if (ires > 3) _xsec[ires - 4]->fill(sqrtS() / GeV);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
const double sf = crossSection() / nanobarn / sumOfWeights();
scale(_nMeson, sf);
scale(_xsec, sf);
for (size_t ih = 0; ih < 4; ++ih) {
barchart(_xsec[ih], _est[ih]);
}
// loop over tables in paper
for (size_t ih = 1; ih < 5; ++ih) {
for (size_t iy = 1; iy < 2; ++iy) {
string iloc = toString(ih + iy - 2);
BinnedEstimatePtr<string> mult;
book(mult, ih, 1, iy);
for (auto& b : mult->bins()) {
const double eVal = stod(b.xEdge());
const string en = toString(round(eVal / MeV));
b.set(_nMeson[en + iloc]->val(), _nMeson[en + iloc]->err());
}
}
}
}
/// @}
/// @name Histograms
/// @{
map<string, CounterPtr> _nMeson;
Histo1DPtr _xsec[5];
Estimate1DPtr _est[5];
string _sqs = "";
/// @}
};
RIVET_DECLARE_PLUGIN(ARGUS_1987_I248680);
}