Rivet analyses

Visible hadronic cross section near the $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(4S)$ resonances

Experiment: ARGUS (DORIS)

Inspire ID: 375418

Status: VALIDATED NOHEPDATA SINGLEWEIGHT

Authors: - Peter Richardson

References: - Z.Phys.C 65 (1995) 619-626

Beams: e- e+

Beam energies: ANY

Run details: - e+ e- to hadrons including the Upsilon resonances

Measurement of the visible hadronic cross section near the $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(4S)$ resonances. As the analyses requires the beam energy smearing described in the paper then central CMS energy should be specified using the ECENT (in GeV) option.

Source code:ARGUS_1994_I375418.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  /// @brief e+ e- > hadrons near Upsilon resonances
  class ARGUS_1994_I375418 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1994_I375418);


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

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

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

      // Book histograms
      for (unsigned int ix = 0; ix < 3; ++ix) book(_sigma[ix], 1 + ix, 1, 1);
      _eCent = getOption<string>("ECENT", std::to_string(sqrtS() / MeV));
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      if (apply<ChargedFinalState>(event, "CFS").particles().size() < 3) vetoEvent;
      const FinalState& fs = apply<FinalState>(event, "FS");
      map<long, int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
        nCount[p.pid()] += 1;
        ++ntotal;
      }
      // mu+mu- + photons
      if (nCount[-13] == 1 and nCount[13] == 1 && ntotal == 2 + nCount[22]) {
        vetoEvent;
      }
      else if (nCount[-11] == 1 and nCount[11] == 1 && ntotal == 2 + nCount[22]) {
        vetoEvent;
      }
      else { // everything else
        _sigma[0]->fill(_eCent);
        _sigma[1]->fill(_eCent);
        double H0 = 0., H2 = 0;
        for (unsigned int ix = 0; ix < fs.particles().size(); ++ix) {
          double p1 = fs.particles()[ix].p3().mod();
          for (unsigned int iy = 0; iy < fs.particles().size(); ++iy) {
            double p2 = fs.particles()[iy].p3().mod();
            double cTheta = fs.particles()[ix].p3().dot(fs.particles()[iy].p3()) / p1 / p2;
            double pre = p1 * p2 / sqr(sqrtS());
            H0 += pre;
            H2 += 0.5 * pre * (3. * sqr(cTheta) - 1);
          }
        }
        if (H2 / H0 < 0.35) _sigma[2]->fill(_eCent);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_sigma, crossSection() / sumOfWeights() / nanobarn);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _sigma[3];
    string _eCent;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(ARGUS_1994_I375418);

}