Rivet analyses

title: TASSO_1982_I179022

$\rho^0$ spectrum in $e^+e^-$ collisions at $E_{\text{CMS}}=34$ GeV

Experiment: TASSO (Petra)

Inspire ID: 179022

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B117 (1982) 135-140, 1982

Beams: e- e+

Beam energies: ANY

Run details: - e+ e- to hadrons

Spectrum for $\rho^0$ production measured by the TASSO experiment in $e^+e^-$ collisions at $E_{\text{CMS}}=34$ GeV at PETRA

Source code:TASSO_1982_I179022.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Add a short analysis description here class TASSO_1982_I179022 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1982_I179022);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");

  // Book histograms
  book(_h_rho, 1, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  // 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);

  for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid == 113)) {
    double xE = p.E() / meanBeamMom;
    double beta = p.p3().mod() / p.E();
    _h_rho->fill(xE, 1. / beta);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h_rho, sqr(sqrtS()) * crossSection() / microbarn / sumOfWeights()); // norm to cross section
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_rho;
/// @}

};

RIVET_DECLARE_PLUGIN(TASSO_1982_I179022);

} ```