Rivet analyses
Neutral strange particle production in deep inelastic scattering at HERA (ZEUS)
Experiment: ZEUS (HERA)
Inspire ID: 395196
Status: VALIDATED
Authors: - Can Sueslue - Hannes Jung
References: - Z. Phys.C 68( 1995) 29 - DOI: 10.1007/BF01579802 - arXiv: hep-ex/9505011
Beams: e- p+, p+ e-
Beam energies: (26.7, 820.0); (820.0, 26.7)GeV
Run details: - Cuts are $10<Q2<640 GeV^2$, $0.0003<x_{bj}<0.01$,and $y>0.04$. For Kaons, $1.3< \eta <1.3$ and $0.5< p_t<4.0 GeV$. For Lambdas $1.3< \eta <1.3 $ and $0.5< p_t<3.5 GeV$.
Measurements of $K^0$ and $\Lambda$ production in neutral current, deep inelastic scattering of 26.7 GeV electrons and 820 GeV protons in the kinematic range $10<Q^2<640$, $0.0003<x<0.01$, and $y>0.04$. Average multiplicities for $K^0$ and $\Lambda$ production are determined for transverse momenta $p_T >0.5> $ GeV and pseudorapidities $|\eta| < 1.3 $. The production properties of $K^0$ in events with and without a large rapidity gap with respect to the proton direction are compared. The ratio of neutral $K^0$ to charged particles per event in the measured kinematic range is, within the present statistics, the same in both samples.
Source code:ZEUS_1995_I395196.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/DISKinematics.hh"
#include "Rivet/Projections/DISLepton.hh"
#include "Rivet/Projections/DISRapidityGap.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Neutral strange particle production in deep inelastic scattering at HERA (ZEUS)
class ZEUS_1995_I395196 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ZEUS_1995_I395196);
void init() {
declare(DISLepton(), "Lepton");
declare(DISKinematics(), "Kinematics");
declare(DISRapidityGap(), "Rapidity Gap");
const Cut cut = Cuts::abseta < 1.3;
const FinalState fs(cut);
declare(fs, "FS");
const UnstableParticles ufs(cut);
declare(ufs, "UFS");
const ChargedFinalState cfs(cut);
declare(cfs, "CFS");
// take binning from reference data using HEPData ID (digits in "d01-x01-y01" etc.)
book(_h["pT_kaon"], 1, 1, 1);
book(_h["eta_kaon"], 2, 1, 1);
book(_h["pT_lambda"], 3, 1, 1);
book(_h["eta_lambda"], 4, 1, 1);
book(_h_multK0_0, "TMP/mult_0", refData<YODA::BinnedEstimate<string>>(5, 1, 1));
book(_h_multK0_1, "TMP/mult_1", refData<YODA::BinnedEstimate<string>>(5, 1, 1));
book(_h_multK0_2, "TMP/mult_2", refData<YODA::BinnedEstimate<string>>(6, 1, 1));
book(_h_multK0_3, "TMP/mult_3", refData<YODA::BinnedEstimate<string>>(6, 1, 1));
book(_h_scatratio, 6, 1, 1);
book(_h["K0_NRG_data_pT"], 7, 1, 1);
book(_h["K0_LRG_data_pT"], 8, 1, 1);
book(_h["K0_NRG_data_eta"], 9, 1, 1);
book(_h["K0_LRG_data_eta"], 10, 1, 1);
book(_h_scat, 5, 1, 1);
book(_c["dis"], "TMP/Nevt_after_cuts");
}
/// Perform the per-event analysis
void analyze(const Event& event) {
if (_edges.empty()) _edges = _h_multK0_0->xEdges();
;
const FinalState& fs = apply<FinalState>(event, "FS");
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
const DISKinematics& dk = apply<DISKinematics>(event, "Kinematics");
const DISRapidityGap& g = apply<DISRapidityGap>(event, "Rapidity Gap");
const ChargedFinalState& charged = apply<ChargedFinalState>(event, "CFS");
const size_t numPartcharged = charged.particles().size();
//const size_t numPart = fs.particles().size();
//_c["charged"] -> fill(numPartcharged);
//_c["all"] -> fill(numPart);
const size_t numParticles = fs.particles().size();
if (numParticles < 2) {
MSG_DEBUG("Failed leptonic event cut");
vetoEvent;
}
double rgap = g.gap();
// Get the DIS kinematics
double xbj = dk.x();
double ybj = dk.y();
double Q2 = dk.Q2() / GeV;
double W = sqrt(dk.W2() / GeV);
bool cut = Q2 > 10 && Q2 < 640 && xbj > 0.0003 && xbj < 0.01 && ybj > 0.04 && ybj < 1.0;
if (!cut) vetoEvent;
size_t idx = _axis.index(Q2);
string edge = "OTHER";
if (idx && idx <= _edges.size()) edge = _edges[idx - 1];
_h_multK0_1->fill(edge);
_h_multK0_2->fill(edge, numPartcharged);
_c["dis"]->fill();
for (const Particle& p : ufs.particles()) {
const double eta = p.eta();
const double pT = p.pT() / GeV;
const int pid = abs(p.pid());
//const double ybj= (p.E()-p.pz())/(2*27.5);
if (pid == 310 || pid == 130) { //K0S
//cout << " pid " << pid << " eta " << eta << endl;
if (pT > 0.5 && pT < 4.0) {
//fill histograms related to the kaons in here.
_h["pT_kaon"]->fill(pT, 0.5 / pT);
_h["eta_kaon"]->fill(eta);
_h_multK0_0->fill(edge);
_h_multK0_3->fill(edge);
if (rgap < 1.5 && W > 140.0) {
_h["K0_LRG_data_pT"]->fill(pT, 0.5 / pT);
_h["K0_LRG_data_eta"]->fill(eta);
//cout<< abs(eta) <<endl;
}
else if (rgap > 1.5 && W > 140.0) {
_h["K0_NRG_data_pT"]->fill(pT, 0.5 / pT);
_h["K0_NRG_data_eta"]->fill(eta);
}
}
}
else if (pid == 3122) { // Lambda
if (pT > 0.5 && pT < 3.5) {
//fill histograms related to the lambdas in here.
_h["pT_lambda"]->fill(pT, 0.5 / pT);
_h["eta_lambda"]->fill(eta);
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
divide(_h_multK0_0, _h_multK0_1, _h_scat);
divide(_h_multK0_3, _h_multK0_2, _h_scatratio);
//cout<< "#of kaons per events"<< kaon/numEvents() <<endl;
//cout<< "Num mean charged p multiplicity"<< *_c["charged"]<< endl;
scale(_h["pT_kaon"], 1. / *_c["dis"]);
scale(_h["eta_kaon"], 1. / *_c["dis"]);
scale(_h["pT_lambda"], 1. / *_c["dis"]);
scale(_h["eta_lambda"], 1. / *_c["dis"]);
scale(_h["K0_LRG_data_pT"], 1. / *_c["dis"]);
scale(_h["K0_NRG_data_pT"], 1. / *_c["dis"]);
scale(_h["K0_LRG_data_eta"], 1. / *_c["dis"]);
scale(_h["K0_NRG_data_eta"], 1. / *_c["dis"]);
}
///@}
private:
/// @name Histograms
///@{
map<string, Histo1DPtr> _h;
map<string, Profile1DPtr> _p;
map<string, CounterPtr> _c;
BinnedEstimatePtr<string> _h_scat, _h_scatratio;
BinnedHistoPtr<string> _h_multK0_0, _h_multK0_1, _h_multK0_2, _h_multK0_3;
YODA::Axis<double> _axis = YODA::Axis<double>{8.98, 12.195, 15.41, 32.535, 106.89, 240.31};
vector<string> _edges;
///@}
};
RIVET_DECLARE_PLUGIN(ZEUS_1995_I395196);
}