Rivet analyses

title: L3_1994_I374698

$\pi^0$ and $\eta$ spectra at 91 GeV

Experiment: L3 ()

Inspire ID: 374698

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett.B 328 (1994) 223-233

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - e+e- -> hadrons

Measurement of the momentum distribution of the $\pi^0$ and $\eta$ mesons at 91.2 GeV in $e^+e^-$ collisions by the L3 collaboration.

Source code:L3_1994_I374698.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief pi0 and eta spectra at 91 GeV class L3_1994_I374698 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(L3_1994_I374698);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(UnstableParticles(), "UFS");
  // book histos
  book(_h_pi0_x_P, 5, 1, 1);
  book(_h_pi0_x_H, 6, 1, 1);
  book(_h_pi0_xi, 7, 1, 1);
  book(_h_eta_x_P, 8, 1, 1);
  book(_h_eta_x_H, 9, 1, 1);
  book(_h_eta_xi, 10, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::pid == PID::PI0 || Cuts::pid == PID::ETA)) {
    const double x = 2. * p.momentum().p3().mod() / sqrtS();
    if (p.pid() == PID::PI0) {
      _h_pi0_x_P->fill(x);
      _h_pi0_x_H->fill(x);
      _h_pi0_xi->fill(-log(x));
    }
    else {
      _h_eta_x_P->fill(x);
      _h_eta_x_H->fill(x);
      _h_eta_xi->fill(-log(x));
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h_pi0_x_P, 1. / sumOfWeights());
  scale(_h_pi0_x_H, 1. / sumOfWeights());
  scale(_h_pi0_xi, 1. / sumOfWeights());
  scale(_h_eta_x_P, 1. / sumOfWeights());
  scale(_h_eta_x_H, 1. / sumOfWeights());
  scale(_h_eta_xi, 1. / sumOfWeights());
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_pi0_x_P, _h_pi0_x_H, _h_pi0_xi;
Histo1DPtr _h_eta_x_P, _h_eta_x_H, _h_eta_xi;
/// @}

};

RIVET_DECLARE_PLUGIN(L3_1994_I374698);

} ```