Rivet analyses

title: HRS_1985_I213242

$\phi$ and $D_s^\pm$ spectra at 29 GeV

Experiment: HRS (PEP)

Inspire ID: 213242

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 54 (1985) 2568

Beams: e+ e-

Beam energies: (14.5, 14.5)GeV

Run details: - e+ e- to hadrons

Measurement of the $\phi$ and $D_s^\pm$ spectra at 29 GeV by the HRS experiment. The PDG2020 value of $D^+_s\to\phi\pi^+$ branching ratio is used.

Source code:HRS_1985_I213242.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief phi and D_s spectra at 29 GeV class HRS_1985_I213242 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(HRS_1985_I213242);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(), "UFS");
  book(_h_phi, 1, 1, 1);
  book(_h_Ds, 2, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  UnstableParticles ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == 431 || Cuts::pid == 333)) {
    double xE = 2. * p.E() / sqrtS();
    Vector3 mom3 = p.p3();
    const double energy = p.E();
    double modp = mom3.mod();
    double beta = modp / energy;
    if (p.pid() == 333)
      _h_phi->fill(xE, 1. / beta);
    else
      _h_Ds->fill(xE, 1. / beta);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // PDG 2020 D_s phi pi br
  double br = 0.045;
  scale(_h_phi, sqr(sqrtS()) * crossSection() / nanobarn / sumOfWeights());
  scale(_h_Ds, br * sqr(sqrtS()) * crossSection() / nanobarn / sumOfWeights());
}

///@}


/// @name Histograms
///@{
Histo1DPtr _h_phi, _h_Ds;
///@}

};

RIVET_DECLARE_PLUGIN(HRS_1985_I213242);

} ```