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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
class ATLAS_2011_I944826 : public Analysis {
public:
/// Constructor
ATLAS_2011_I944826()
: Analysis("ATLAS_2011_I944826")
{}
/// Book histograms and initialise projections before the run
void init() {
book(_sum_w_ks , "ks");
book(_sum_w_lambda, "lambda");
book(_sum_w_passed, "passed");
UnstableParticles ufs(Cuts::pT > 100*MeV);
declare(ufs, "UFS");
ChargedFinalState mbts(Cuts::absetaIn(2.09, 3.84));
declare(mbts, "MBTS");
IdentifiedFinalState nstable(Cuts::abseta < 2.5 && Cuts::pT >= 100*MeV);
nstable.acceptIdPair(PID::ELECTRON)
.acceptIdPair(PID::MUON)
.acceptIdPair(PID::PIPLUS)
.acceptIdPair(PID::KPLUS)
.acceptIdPair(PID::PROTON);
declare(nstable, "nstable");
if (isCompatibleWithSqrtS(7000)) {
book(_hist_Ks_pT ,1, 1, 1);
book(_hist_Ks_y ,2, 1, 1);
book(_hist_Ks_mult ,3, 1, 1);
book(_hist_L_pT ,7, 1, 1);
book(_hist_L_y ,8, 1, 1);
book(_hist_L_mult ,9, 1, 1);
book(_hist_Ratio_v_y ,13, 1, 1);
book(_hist_Ratio_v_pT,14, 1, 1);
//
book(_temp_lambda_v_y, "TMP/lambda_v_y", 10, 0.0, 2.5);
book(_temp_lambdabar_v_y, "TMP/lambdabar_v_y", 10, 0.0, 2.5);
book(_temp_lambda_v_pT, "TMP/lambda_v_pT", 18, 0.5, 4.1);
book(_temp_lambdabar_v_pT, "TMP/lambdabar_v_pT", 18, 0.5, 4.1);
}
else if (isCompatibleWithSqrtS(900)) {
book(_hist_Ks_pT ,4, 1, 1);
book(_hist_Ks_y ,5, 1, 1);
book(_hist_Ks_mult ,6, 1, 1);
book(_hist_L_pT ,10, 1, 1);
book(_hist_L_y ,11, 1, 1);
book(_hist_L_mult ,12, 1, 1);
book(_hist_Ratio_v_y ,15, 1, 1);
book(_hist_Ratio_v_pT,16, 1, 1);
//
book(_temp_lambda_v_y, "TMP/lambda_v_y", 5, 0.0, 2.5);
book(_temp_lambdabar_v_y, "TMP/lambdabar_v_y", 5, 0.0, 2.5);
book(_temp_lambda_v_pT, "TMP/lambda_v_pT", 8, 0.5, 3.7);
book(_temp_lambdabar_v_pT, "TMP/lambdabar_v_pT", 8, 0.5, 3.7);
}
}
// This function is required to impose the flight time cuts on Kaons and Lambdas
double getPerpFlightDistance(const Rivet::Particle& p) {
ConstGenParticlePtr genp = p.genParticle();
ConstGenVertexPtr prodV = genp->production_vertex();
ConstGenVertexPtr decV = genp->end_vertex();
RivetHepMC::FourVector prodPos = prodV->position();
if (decV) {
const RivetHepMC::FourVector decPos = decV->position();
double dy = prodPos.y() - decPos.y();
double dx = prodPos.x() - decPos.x();
return add_quad(dx, dy);
}
return numeric_limits<double>::max();
}
bool daughtersSurviveCuts(const Rivet::Particle& p) {
// We require the Kshort or Lambda to decay into two charged
// particles with at least pT = 100 MeV inside acceptance region
ConstGenParticlePtr genp = p.genParticle();
ConstGenVertexPtr decV = genp->end_vertex();
bool decision = true;
if (!decV) return false;
if (HepMCUtils::particles(decV, Relatives::CHILDREN).size() == 2) {
std::vector<double> pTs;
std::vector<int> charges;
std::vector<double> etas;
for(ConstGenParticlePtr gp: HepMCUtils::particles(decV, Relatives::CHILDREN)) {
pTs.push_back(gp->momentum().perp());
etas.push_back(fabs(gp->momentum().eta()));
charges.push_back( Rivet::PID::charge3(gp->pdg_id()) );
// gp->print();
}
if ( (pTs[0]/Rivet::GeV < 0.1) || (pTs[1]/Rivet::GeV < 0.1) ) {
decision = false;
MSG_DEBUG("Failed pT cut: " << pTs[0]/Rivet::GeV << " " << pTs[1]/Rivet::GeV);
}
if ( etas[0] > 2.5 || etas[1] > 2.5 ) {
decision = false;
MSG_DEBUG("Failed eta cut: " << etas[0] << " " << etas[1]);
}
if ( charges[0] * charges[1] >= 0 ) {
decision = false;
MSG_DEBUG("Failed opposite charge cut: " << charges[0] << " " << charges[1]);
}
}
else {
decision = false;
MSG_DEBUG("Failed nDaughters cut: " << HepMCUtils::particles(decV, Relatives::CHILDREN).size());
}
return decision;
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// ATLAS MBTS trigger requirement of at least one hit in either hemisphere
if (apply<FinalState>(event, "MBTS").size() < 1) {
MSG_DEBUG("Failed trigger cut");
vetoEvent;
}
// Veto event also when we find less than 2 particles in the acceptance region of type 211,2212,11,13,321
if (apply<FinalState>(event, "nstable").size() < 2) {
MSG_DEBUG("Failed stable particle cut");
vetoEvent;
}
_sum_w_passed->fill();
// This ufs holds all the Kaons and Lambdas
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
// Some conters
int n_KS0 = 0;
int n_LAMBDA = 0;
// Particle loop
for (const Particle& p : ufs.particles()) {
// General particle quantities
const double pT = p.pT();
const double y = p.rapidity();
const PdgId apid = p.abspid();
double flightd = 0.0;
// Look for Kaons, Lambdas
switch (apid) {
case PID::K0S:
flightd = getPerpFlightDistance(p);
if (!inRange(flightd/mm, 4., 450.) ) {
MSG_DEBUG("Kaon failed flight distance cut:" << flightd);
break;
}
if (daughtersSurviveCuts(p) ) {
_hist_Ks_y ->fill(y);
_hist_Ks_pT->fill(pT/GeV);
_sum_w_ks->fill();
n_KS0++;
}
break;
case PID::LAMBDA:
if (pT < 0.5*GeV) { // Lambdas have an additional pT cut of 500 MeV
MSG_DEBUG("Lambda failed pT cut:" << pT/GeV << " GeV");
break;
}
flightd = getPerpFlightDistance(p);
if (!inRange(flightd/mm, 17., 450.)) {
MSG_DEBUG("Lambda failed flight distance cut:" << flightd/mm << " mm");
break;
}
if ( daughtersSurviveCuts(p) ) {
if (p.pid() == PID::LAMBDA) {
_temp_lambda_v_y->fill(fabs(y));
_temp_lambda_v_pT->fill(pT/GeV);
_hist_L_y->fill(y);
_hist_L_pT->fill(pT/GeV);
_sum_w_lambda->fill();
n_LAMBDA++;
} else if (p.pid() == -PID::LAMBDA) {
_temp_lambdabar_v_y->fill(fabs(y));
_temp_lambdabar_v_pT->fill(pT/GeV);
}
}
break;
}
}
// Fill multiplicity histos
_hist_Ks_mult->fill(n_KS0);
_hist_L_mult->fill(n_LAMBDA);
}
/// Normalise histograms etc., after the run
void finalize() {
MSG_DEBUG("# Events that pass the trigger: " << dbl(*_sum_w_passed));
MSG_DEBUG("# Kshort events: " << dbl(*_sum_w_ks));
MSG_DEBUG("# Lambda events: " << dbl(*_sum_w_lambda));
/// @todo Replace with normalize()?
scale(_hist_Ks_pT, 1.0 / *_sum_w_ks);
scale(_hist_Ks_y, 1.0 / *_sum_w_ks);
scale(_hist_Ks_mult, 1.0 / *_sum_w_passed);
/// @todo Replace with normalize()?
scale(_hist_L_pT, 1.0 / *_sum_w_lambda);
scale(_hist_L_y, 1.0 / *_sum_w_lambda);
scale(_hist_L_mult, 1.0 / *_sum_w_passed);
// Division of histograms to obtain lambda_bar/lambda ratios
divide(_temp_lambdabar_v_y, _temp_lambda_v_y, _hist_Ratio_v_y);
divide(_temp_lambdabar_v_pT, _temp_lambda_v_pT, _hist_Ratio_v_pT);
}
private:
/// Counters
CounterPtr _sum_w_ks, _sum_w_lambda, _sum_w_passed;
/// @name Persistent histograms
//@{
Histo1DPtr _hist_Ks_pT, _hist_Ks_y, _hist_Ks_mult;
Histo1DPtr _hist_L_pT, _hist_L_y, _hist_L_mult;
Scatter2DPtr _hist_Ratio_v_pT, _hist_Ratio_v_y;
//@}
/// @name Temporary histograms
//@{
Histo1DPtr _temp_lambda_v_y, _temp_lambdabar_v_y;
Histo1DPtr _temp_lambda_v_pT, _temp_lambdabar_v_pT;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(ATLAS_2011_I944826);
}
|