Rivet analyses

ϕ and Ds± 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 ϕ and Ds± spectra at 29 GeV by the HRS experiment. The PDG2020 value of Ds+ → ϕπ+ branching ratio is used.

Source code:HRS_1985_I213242.cc

// -*- 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);

}