Rivet analyses

B− → p̄Λ0D0 Differential branching ratio

Experiment: BELLE (KEKB)

Inspire ID: 924618

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 84 (2011) 071501

Beams: * *

Beam energies: ANY

Run details: - Any process producing B+/-, originally e+e- at Upsilon(4S)

Differential branching ratio for B− → p̄Λ0D0 as a function of the p̄Λ0 mass measured by BELLE.

Source code:BELLE_2011_I924618.cc

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

namespace Rivet {


  /// @brief B- -> pbar Lambda D0
  class BELLE_2011_I924618 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2011_I924618);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BP(ufs);
      BP.addStable(3122);
      BP.addStable(-3122);
      BP.addStable(421);
      BP.addStable(-421);
      declare(BP, "BP");
      // histos
      book(_h, 1, 1, 1);
      book(_c, "TMP/nB");
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{-2212, 1}, {3122, 1}, {421, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{2212, 1}, {-3122, 1}, {-421, 1}};
      DecayedParticles BP = apply<DecayedParticles>(event, "BP");
      // loop over particles
      for (unsigned int ix = 0; ix < BP.decaying().size(); ++ix) {
        _c->fill();
        int sign = 1;
        if (BP.decaying()[ix].pid() < 0 && BP.modeMatches(ix, 3, mode)) {
          sign = 1;
        }
        else if (BP.decaying()[ix].pid() > 0 && BP.modeMatches(ix, 3, modeCC)) {
          sign = -1;
        }
        else
          continue;
        const Particle& pbar = BP.decayProducts()[ix].at(-sign * 2212)[0];
        const Particle& Lam = BP.decayProducts()[ix].at(sign * 3122)[0];
        _h->fill((pbar.momentum() + Lam.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h, 1e6 / *_c);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h;
    CounterPtr _c;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2011_I924618);

}