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Rivet analyses reference
CELLO_1989_I276764
Photon, $\pi^0$ and $\eta$ spectra at 35 GeV
Experiment: CELLO (Petra)
Inspire ID: 276764
Status: VALIDATED
Authors:
References:
- Z.Phys. C47 (1990) 1-10, 1990
Beams: e+ e-
Beam energies: (17.5, 17.5) GeV
Run details:
Measurement of the $\gamma$, $\pi^0$ and $\eta$ energy fractions in $e^+e^-$ collisions for centre-of-mass energy of 35 GeV by the CELLO experiment at Petra. Only the bin centroids are given in the paper and HEPdata so the bin widths have been inferred.
Source code:
CELLO_1989_I276764.cc
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98 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/Beam.hh"
namespace Rivet {
/// @brief Add a short analysis description here
class CELLO_1989_I276764 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CELLO_1989_I276764);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(Beam(), "Beams");
declare(FinalState(), "FS");
declare(UnstableParticles(), "UFS");
// Book histograms
book(_h_gamma , 2, 1, 1);
book(_h_pi0A , 3, 1, 1);
book(_h_pi0B , 4, 1, 1);
book(_h_eta , 5, 1, 1);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// at least 5 charged FS particles
const FinalState& fs = apply<FinalState>(event, "FS");
const size_t numParticles = fs.particles().size();
if (numParticles < 5) {
MSG_DEBUG("Failed leptonic event cut");
vetoEvent;
}
MSG_DEBUG("Passed leptonic event cut");
// Get beams and average beam momentum
const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
const double meanBeamMom = ( beams.first.p3().mod() +
beams.second.p3().mod() ) / 2.0;
MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
// Final state to get particle spectra
for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==111 || Cuts::pid==221)) {
double xE = p.E()/meanBeamMom;
if(p.pid()==111) {
_h_pi0A->fill(xE);
_h_pi0B->fill(xE);
}
else
_h_eta->fill(xE);
}
for (const Particle& p : apply<FinalState>(event, "FS").particles(Cuts::pid==111 || Cuts::pid==22)) {
double xE = p.E()/meanBeamMom;
if(p.pid()==22)
_h_gamma->fill(xE);
}
}
/// Normalise histograms etc., after the run
void finalize() {
double fact = sqr(sqrtS())/GeV2*crossSection()/microbarn/sumOfWeights();
scale(_h_gamma, fact);
scale(_h_pi0A , fact);
scale(_h_pi0B , fact);
scale(_h_eta , fact);
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_gamma,_h_pi0A,_h_pi0B,_h_eta;
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(CELLO_1989_I276764);
}
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