Rivet analyses

title: DELPHI_1994_I375963

A study of radiative muon pair events at Z0 energies

Experiment: DELPHI (LEP)

Inspire ID: 375963

Status: VALIDATED NOTREENTRY NOHEPDATA

Authors: - Markus Seidel

References: - Z.Phys.C 65 (1995) 603-618 - DOI:10.1007/BF01578669 - CERN-PPE-94-121 - CERN-DELPHI-THESIS-111

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - e+ e- > mu+ mu-, including ISR

Differential cross sections of the radiative photons as a function of photon energy and of the angle between the photon and the muon. Data points were digitised from the note, +8% photon efficiency uncertainty (as described in thesis), and divided by bin width for the Rivet analysis.

Source code:DELPHI_1994_I375963.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/PromptFinalState.hh"

namespace Rivet {

/// @brief A study of radiative muon pair events at Z0 energies class DELPHI_1994_I375963 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_1994_I375963);


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

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

  // FinalState of prompt photons and muons
  declare(PromptFinalState(Cuts::abspid == PID::MUON && Cuts::energy > 20 * GeV), "muons");
  declare(PromptFinalState(Cuts::abspid == PID::PHOTON && Cuts::energy > 2 * GeV), "photons");

  // Book histograms
  book(_h["ph_energy"], 1, 1, 1);
  book(_h["ph_angle"], 2, 1, 1);
}


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

  Particles muons = apply<PromptFinalState>(event, "muons").particles();
  Particles photons = apply<PromptFinalState>(event, "photons").particles();

  iselect(muons, [](const Particle& muon) {
    double theta = muon.theta() / M_PI * 180.;
    return (theta > 20. && theta < 160.);
  });

  iselect(photons, [](const Particle& photon) {
    double theta = photon.theta() / M_PI * 180.;
    double phi = photon.phi() / M_PI * 180.;

    bool femc = (theta > 10. && theta < 36.5) || (theta > 143.5 && theta < 170.);
    bool hpc = theta > 43. && theta < 137. && abs(fmod(phi, 15.)) > 1.5 && abs(theta - 90.) > 2.;

    return (femc || hpc);
  });

  if (muons.size() != 2) vetoEvent;
  if (photons.size() == 0) vetoEvent;

  for (const Particle& photon : photons) {
    double minAngle = 1000.;
    for (const Particle& muon : muons) {
      double angle = photon.angle(muon) / M_PI * 180.;
      if (angle < minAngle) {
        minAngle = angle;
      }
    }
    if (minAngle > 5.) {
      _h["ph_energy"]->fill(photon.energy() / GeV);
      _h["ph_angle"]->fill(minAngle);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {

  scale({_h["ph_energy"], _h["ph_angle"]}, 1. / sumW());
}

/// @}


/// @name Histograms
/// @{
map<string, Histo1DPtr> _h;
/// @}

};

RIVET_DECLARE_PLUGIN(DELPHI_1994_I375963);

} ```