Rivet analyses

title: KLOE_2009_I797438

Cross section for $e^+e^-\to\pi^+\pi^-$ below 0.93 GeV

Experiment: KLOE (DAPHNE)

Inspire ID: 797438

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B670 (2009) 285-291, 2009

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons

Measurement of the cross section for $e^+e^-\to\pi^+\pi^-$ below 0.93 GeV

Source code:KLOE_2009_I797438.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- -> pi+pi- class KLOE_2009_I797438 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(KLOE_2009_I797438);


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

/// Book histograms and initialise projections before the run
void init() {

  // Initialise and register projections
  declare(FinalState(), "FS");

  // Book histograms
  book(_npion, "TMP/pion", refData(1, 1, 1));
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");
  if (fs.particles().size() != 2) vetoEvent;
  for (const Particle& p : fs.particles()) {
    if (abs(p.pid()) != PID::PIPLUS) vetoEvent;
  }
  _npion->fill(sqr(sqrtS() / GeV));
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_npion, crossSection() / sumOfWeights() / nanobarn);
  Estimate1DPtr mult;
  book(mult, 2, 1, 1);
  barchart(_npion, mult);
}

/// @}


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

};

RIVET_DECLARE_PLUGIN(KLOE_2009_I797438);

} ```