Rivet analyses

title: OPAL_1998_I467092

Production of $f_0(980)$, $f_2(1270)$ and $\phi(1020)$ in hadronic $Z^0$ decay

Experiment: OPAL (LEP 1)

Inspire ID: 467092

Status: VALIDATED

Authors: - Peter Richardson

References: - Eur.Phys.J.C4:19-28,1998 - hep-ex/9802013

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - Hadronic Z decay events generated on the Z pole ($\sqrt{s} = 91.2$ GeV)

Inclusive production of the $f_0(980)$, $f_2(1270)$ and $\phi(1020)$ resonances studied in a sample of 4.3 million hadronic $Z^0$ decays from the OPAL experiment at LEP. Fragmentation functions are reported for the three states.

Source code:OPAL_1998_I467092.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief OPAL f0,f2 and phi fragmentation function paper /// /// @author Peter Richardson class OPAL_1998_I467092 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1998_I467092);


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

void init() {
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  book(_histXpf0, 2, 1, 1);
  book(_histXpf2, 2, 1, 2);
  book(_histXpPhi, 2, 1, 3);
}


void analyze(const Event& e) {
  // First, veto on leptonic events by requiring at least 4 charged FS particles
  const FinalState& fs = apply<FinalState>(e, "FS");
  const size_t numParticles = fs.particles().size();

  // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
  if (numParticles < 2) {
    MSG_DEBUG("Failed leptonic event cut");
    vetoEvent;
  }
  MSG_DEBUG("Passed leptonic event cut");

  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
  const double meanBeamMom = (beams.first.p3().mod() + beams.second.p3().mod()) / 2.0;
  MSG_DEBUG("Avg beam momentum = " << meanBeamMom);

  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");

  for (const Particle& p : ufs.particles()) {
    const int id = p.abspid();
    double xp = p.p3().mod() / meanBeamMom;
    switch (id) {
      case 9010221: _histXpf0->fill(xp); break;
      case 225: _histXpf2->fill(xp); break;
      case 333: _histXpPhi->fill(xp); break;
    }
  }
}


/// Finalize
void finalize() {
  scale(_histXpf0, 1. / sumOfWeights());
  scale(_histXpf2, 1. / sumOfWeights());
  scale(_histXpPhi, 1. / sumOfWeights());
}

/// @}

private:

/// @{
Histo1DPtr _histXpf0;
Histo1DPtr _histXpf2;
Histo1DPtr _histXpPhi;
/// @}

};

RIVET_DECLARE_ALIASED_PLUGIN(OPAL_1998_I467092, OPAL_1998_S3702294);

} ```

Aliases: - OPAL_1998_S3702294