Rivet analyses

Cross section for (BB*)±π∓ and (B*B*)±π∓ for $\sqrt{s}=10.866$ GeV

Experiment: BELLE (KEKB)

Inspire ID: 1411223

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 116 (2016) 21, 212001

Beams: e+ e-

Beam energies: (5.4, 5.4)GeV

Run details: - e+ e- to hadrons, pi0 set stable

Measurement of the cross section for (BB*)±π∓ and (B*B*)±π∓ at $\sqrt{s}=10.866$ GeV.

Source code:BELLE_2015_I1411223.cc

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

namespace Rivet {


  /// @brief e+e- > B(*) B* pi
  class BELLE_2015_I1411223 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2015_I1411223);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(FinalState(), "FS");
      // histograms
      for (unsigned int ix = 0; ix < 2; ++ix) {
        book(_h[ix], 1, 1, 1 + ix);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      Particles fs = apply<FinalState>(event, "FS").particles();
      Particles BB, other;
      for (const Particle& p : fs) {
        Particle parent = p;
        while (!parent.parents().empty()) {
          parent = parent.parents()[0];
          if (parent.abspid() == 511 || parent.abspid() == 521 || parent.abspid() == 513
              || parent.abspid() == 523)
            break;
        }
        if ((parent.abspid() == 511 || parent.abspid() == 521) && !parent.parents().empty()) {
          Particle Bstar = parent.parents()[0];
          if (Bstar.abspid() == 513 || Bstar.abspid() == 523) {
            parent = Bstar;
          }
        }
        if (parent.abspid() == 511 || parent.abspid() == 521 || parent.abspid() == 513
            || parent.abspid() == 523) {
          bool found = false;
          for (const auto& B : BB) {
            // B already in list
            if (fuzzyEquals(B.mom(), parent.mom())) {
              found = true;
              break;
            }
          }
          if (!found) BB += parent;
        }
        else {
          other += p;
        }
      }
      // B Bbar + charged pion
      if (BB.size() != 2 || other.size() != 1) vetoEvent;
      if (BB[0].pid() * BB[1].pid() > 0) vetoEvent;
      if (other[0].abspid() != 211) vetoEvent;
      if (BB[0].abspid() % 10 != 3) swap(BB[0], BB[1]);
      // B0 B*- pi+ +cc
      if ((BB[0].pid() == -513 && BB[1].pid() == 521 && other[0].pid() == -211)
          || (BB[0].pid() == 513 && BB[1].pid() == -521 && other[0].pid() == 211)
          || (BB[0].pid() == 523 && BB[1].pid() == -511 && other[0].pid() == -211)
          || (BB[0].pid() == -523 && BB[1].pid() == 511 && other[0].pid() == 211)) {
        _h[0]->fill("10.866"s);
      }
      else if ((BB[0].pid() == -513 && BB[1].pid() == 523 && other[0].pid() == -211)
               || (BB[0].pid() == 513 && BB[1].pid() == -523 && other[0].pid() == 211)
               || (BB[0].pid() == 523 && BB[1].pid() == -513 && other[0].pid() == -211)
               || (BB[0].pid() == -523 && BB[1].pid() == 513 && other[0].pid() == 211)) {
        _h[1]->fill("10.866"s);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h, crossSection() / sumOfWeights() / picobarn);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _h[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2015_I1411223);

}