Rivet analyses

Anti-deuteron production in Υ decays

Experiment: ARGUS (DORIS)

Inspire ID: 283027

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B236 (1990) 102-108

Beams: * *

Beam energies: ANY

Run details: - Upsilon(1S) decays (originally e+e- production)

Measurement of the anti-deuteron spectrum in Υ(1S) decays. The measurement was original an average of both Υ(1S) and Υ(2S) decays but the Υ(2S) sample is re-scaled to the Υ(1S).

Source code:ARGUS_1990_I283027.cc

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

namespace Rivet {


  /// @brief anti-deuteron spectrum in upslion decays
  class ARGUS_1990_I283027 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1990_I283027);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      // histograms
      book(_h_p, 1, 1, 1);
      book(_w_ups, "TMP/w_ups");
    }


    /// Recursively walk the decay tree to find decay products of @a p
    void findDecayProducts(Particle mother, Particles& deut) {
      // deuteron id code
      static const long id = -1000010020;
      for (const Particle& p : mother.children()) {
        if (p.pid() == id) {
          deut.push_back(p);
        }
        else if (!p.children().empty())
          findDecayProducts(p, deut);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      for (const Particle& ups : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid == 553)) {
        _w_ups->fill();
        Particles deut;
        findDecayProducts(ups, deut);
        if (deut.empty()) continue;
        LorentzTransform boost;
        if (ups.p3().mod() > 1 * MeV)
          boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
        for (const Particle& p : deut) {
          double mom = boost.transform(p.momentum()).p3().mod();
          _h_p->fill(mom);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // direct upsilon decays, i.e. to gg gamma and ggg so need to renormalize
      // factor and values from arxiv:0612019
      double Bmumu = 0.0249, rhad = 3.56;
      double fact = 1. - (3. + rhad) * Bmumu;
      scale(_h_p, 1e5 / fact / *_w_ups);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_p;
    CounterPtr _w_ups;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(ARGUS_1990_I283027);

}