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Rivet analyses reference
CELLO_1983_I191415
Photon and $\pi^0$ spectra in $e^+e^-$ at 14, 22 and 34 GeV
Experiment: CELLO (Petra)
Inspire ID: 191415
Status: VALIDATED
Authors:
References:
- Z.Phys. C20 (1983) 207, 1983
Beams: e+ e-
Beam energies: (7.0, 7.0); (11.0, 11.0); (17.0, 17.0) GeV
Run details:
- e+ e- to hadrons. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.
Measurement of the $\gamma$ and $\pi^0$ energy fractions in $e^+e^-$ collisions for centre-of-mass energies of 14, 22 and 34 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. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.
Source code:
CELLO_1983_I191415.cc
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102 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/Beam.hh"
namespace Rivet {
/// @brief pi0 and gamma spectra at 14, 22 and 34
class CELLO_1983_I191415 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CELLO_1983_I191415);
/// @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");
unsigned int iloc(0);
if(isCompatibleWithSqrtS(14.)) {
iloc=1;
}
else if (isCompatibleWithSqrtS(22.)) {
iloc=2;
}
else if (isCompatibleWithSqrtS(34.)) {
iloc=3;
}
else
MSG_ERROR("Beam energy not supported!");
// Book histograms
book(_h_gamma, iloc , 1, 1);
book(_h_pi0 , iloc+3, 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)) {
double xE = p.E()/meanBeamMom;
_h_pi0->fill(xE);
}
for (const Particle& p : apply<FinalState>(event, "FS").particles(Cuts::pid==22)) {
double xE = p.E()/meanBeamMom;
_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_pi0 , fact);
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_gamma,_h_pi0;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(CELLO_1983_I191415);
}
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