Rivet analyses

Mass distributions in B− → Σc++p̄π−π−

Experiment: BABAR (PEP-II)

Inspire ID: 1127599

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 86 (2012) 091102

Beams: * *

Beam energies: ANY

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

Measurements of mass distributions in B− → Σc++p̄π−π−. The data were read from the plots in the paper but are background subtracted and efficiency corrected.

Source code:BABAR_2012_I1127599.cc

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

namespace Rivet {


  /// @brief B- -> Sigma_c++ pbar pi- pi-
  class BABAR_2012_I1127599 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2012_I1127599);


    /// @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(4222);
      BP.addStable(-4222);
      declare(BP, "BP");
      // histos
      for (unsigned int ix = 0; ix < 3; ++ix) book(_h[ix], 1 + ix, 1, 1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{4222, 1}, {-2212, 1}, {-211, 2}};
      static const map<PdgId, unsigned int>& modeCC = {{-4222, 1}, {2212, 1}, {211, 2}};
      DecayedParticles BP = apply<DecayedParticles>(event, "BP");
      // loop over particles
      for (unsigned int ix = 0; ix < BP.decaying().size(); ++ix) {
        int sign = 1;
        if (BP.decaying()[ix].pid() < 0 && BP.modeMatches(ix, 4, mode)) {
          sign = 1;
        }
        else if (BP.decaying()[ix].pid() > 0 && BP.modeMatches(ix, 4, modeCC)) {
          sign = -1;
        }
        else
          continue;
        const Particle& SigC = BP.decayProducts()[ix].at(sign * 4222)[0];
        const Particle& pbar = BP.decayProducts()[ix].at(-sign * 2212)[0];
        const Particles& pim = BP.decayProducts()[ix].at(-sign * 211);
        for (unsigned int ix = 0; ix < 2; ++ix) {
          _h[0]->fill((pbar.momentum() + pim[ix].momentum()).mass());
          _h[1]->fill((SigC.momentum() + pim[ix].momentum()).mass());
        }
        _h[2]->fill((SigC.momentum() + pim[0].momentum() + pim[1].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_2012_I1127599);

}