Rivet analyses

Photon Energy and Hadronic mass spectrum in B → Xsℓ+ℓ−

Experiment: BELLE (KEKB)

Inspire ID: 899499

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - PoS ICHEP2010 (2010) 231

Beams: * *

Beam energies: ANY

Run details: none listed

Measurement of the photon energy and hadronic mass spectrum in B → Xsℓ+ℓ−. This conference proceding is more recent than the publication in BELLE_2005_I679052, however the data had to be read from the figures.

Source code:BELLE_2010_I899499.cc

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

namespace Rivet {


  /// @brief B -> Xs l+ l-
  class BELLE_2010_I899499 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2010_I899499);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(UnstableParticles(Cuts::abspid == 521 || Cuts::abspid == 511), "UFS");
      // histos
      for (unsigned int ix = 0; ix < 2; ++ix) {
        book(_h[ix], 1, 1, 1 + ix);
      }
      book(_c, "TMP/Nb");
    }

    void findDecayProducts(bool& charm,
                           const Particle& mother,
                           unsigned int& nK0,
                           unsigned int& nKp,
                           unsigned int& nKm,
                           Particles& lp,
                           Particles& lm) {
      for (const Particle& p : mother.children()) {
        int id = p.pid();
        if (PID::isCharmHadron(p.pid()))
          charm = true;
        else if (id == PID::POSITRON || id == PID::ANTIMUON)
          lp.push_back(p);
        else if (id == PID::ELECTRON || id == PID::MUON)
          lm.push_back(p);
        else if (id == PID::KPLUS)
          ++nKp;
        else if (id == PID::KMINUS)
          ++nKm;
        else if (id == PID::K0S)
          ++nK0;
        else if (id == PID::PI0 || id == PID::PIPLUS || id == PID::PIMINUS) {
          continue;
        }
        else if (!p.children().empty()) {
          findDecayProducts(charm, p, nK0, nKp, nKm, lp, lm);
        }
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // Loop over bottoms
      for (const Particle& bottom : apply<UnstableParticles>(event, "UFS").particles()) {
        // remove mixing entries etc
        if (bottom.children()[0].abspid() == bottom.abspid()) continue;
        _c->fill();
        bool charm = false;
        Particles lp, lm;
        unsigned int nK0(0), nKp(0), nKm(0);
        findDecayProducts(charm, bottom, nK0, nKp, nKm, lp, lm);
        if (charm) continue;
        unsigned int nk = nKp - nKm + nK0;
        if (nk % 2 == 0) continue;
        if (lp.size() != 1 || lm.size() != 1 || lp[0].pid() != -lm[0].pid()) continue;
        FourMomentum qq = lp[0].mom() + lm[0].mom();
        double q2 = qq.mass2();
        if (q2 < 0.04) continue;
        _h[0]->fill((bottom.mom() - qq).mass());
        _h[1]->fill(q2);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h, 0.5e6 / *_c);
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _c;
    Histo1DPtr _h[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2010_I899499);

}