Rivet analyses

Mass distributions in B̄0 → Λc+Λ̄0K−

Experiment: BABAR (PEP-II)

Inspire ID: 924163

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 84 (2011) 071102

Beams: * *

Beam energies: ANY

Run details: - Any process producing B0, originally e+e- at Upsilon(4S)

Mass distributions in B̄0 → Λc+Λ̄0K−, data read from plots in papers but is background subtracted.

Source code:BABAR_2011_I924163.cc

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

namespace Rivet {


  /// @brief Bbar0 -> Lambda_c+ Lambdabar K-
  class BABAR_2011_I924163 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2011_I924163);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
      declare(ufs, "UFS");
      DecayedParticles B0(ufs);
      B0.addStable(3122);
      B0.addStable(-3122);
      B0.addStable(4122);
      B0.addStable(-4122);
      declare(B0, "B0");
      // histos
      for (unsigned int ix = 0; ix < 3; ++ix) book(_h[ix], 1, 1, 1 + ix);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{4122, 1}, {-3122, 1}, {-321, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{-4122, 1}, {3122, 1}, {321, 1}};
      DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
      // loop over particles
      for (unsigned int ix = 0; ix < B0.decaying().size(); ++ix) {
        int sign = 1;
        if (B0.decaying()[ix].pid() < 0 && B0.modeMatches(ix, 3, mode)) {
          sign = 1;
        }
        else if (B0.decaying()[ix].pid() > 0 && B0.modeMatches(ix, 3, modeCC)) {
          sign = -1;
        }
        else
          continue;
        const Particle& LamC = B0.decayProducts()[ix].at(sign * 4122)[0];
        const Particle& Lam = B0.decayProducts()[ix].at(-sign * 3122)[0];
        const Particle& Km = B0.decayProducts()[ix].at(-sign * 321)[0];
        _h[0]->fill((LamC.momentum() + Lam.momentum()).mass());
        _h[1]->fill((Lam.momentum() + Km.momentum()).mass());
        _h[2]->fill((LamC.momentum() + Km.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 3; ++ix) normalize(_h[ix], 1., false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[3];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2011_I924163);

}