Rivet analyses

Production of charged pions, kaons, and protons in e+e− annihilations into hadrons at $\sqrt{s}=10.54$GeV

Experiment: BaBar (PEP-II)

Inspire ID: 1238276

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D88 (2013) 3, 032011 - arXiv: 1306.2895 - DOI: 10.1103/PhysRevD.88.032011

Beams: e+ e-

Beam energies: (3.5, 8.0)GeV

Run details: - e+e− analysis in the continuum near the Υ(4S) resonance, with CoM boosts of 8.0GeV(e−) and 3.5GeV(e+)

Measurement of charged pion, kaon and proton production in e+e− collisions with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy of 10.54 GeV. This is a measurement in the continuum.

Source code:BABAR_2013_I1238276.cc

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

namespace Rivet {


  /// @brief BaBar pion, kaon and proton production in the continuum
  /// @author Peter Richardson
  class BABAR_2013_I1238276 : public Analysis {
  public:

    BABAR_2013_I1238276()
        : Analysis("BABAR_2013_I1238276") { }


    void init() {
      declare(Beam(), "Beams");
      declare(ChargedFinalState(), "FS");

      book(_histPion_no_dec, 1, 1, 1);
      book(_histKaon_no_dec, 1, 1, 2);
      book(_histProton_no_dec, 1, 1, 3);
      book(_histPion_dec, 2, 1, 1);
      book(_histKaon_dec, 2, 1, 2);
      book(_histProton_dec, 2, 1, 3);
    }


    void analyze(const Event& e) {
      // Loop through charged FS particles and look for charmed mesons/baryons
      const ChargedFinalState& fs = apply<ChargedFinalState>(e, "FS");

      const Beam beamproj = apply<Beam>(e, "Beams");
      const ParticlePair& beams = beamproj.beams();
      const FourMomentum mom_tot = beams.first.momentum() + beams.second.momentum();
      const LorentzTransform cms_boost = LorentzTransform::mkFrameTransformFromBeta(mom_tot.betaVec());
      MSG_DEBUG("CMS Energy sqrt s = " << beamproj.sqrtS());

      for (const Particle& p : fs.particles()) {
        // check if prompt or not
        ConstGenParticlePtr pmother = p.genParticle();
        ConstGenVertexPtr ivertex = pmother->production_vertex();
        bool prompt = true;
        while (ivertex) {
          vector<ConstGenParticlePtr> inparts = HepMCUtils::particles(ivertex, Relatives::PARENTS);
          int n_inparts = inparts.size();
          if (n_inparts < 1) break;
          pmother = inparts[0]; // first mother particle
          int mother_pid = abs(pmother->pdg_id());
          if (mother_pid == PID::K0S || mother_pid == PID::LAMBDA) {
            prompt = false;
            break;
          }
          else if (mother_pid < 6) {
            break;
          }
          ivertex = pmother->production_vertex();
        }

        // momentum in CMS frame
        const double mom = cms_boost.transform(p.momentum()).vector3().mod();
        const int PdgId = p.abspid();
        MSG_DEBUG("pdgID = " << PdgId << " Momentum = " << mom);
        switch (PdgId) {
          case PID::PIPLUS:
            if (prompt) _histPion_no_dec->fill(mom);
            _histPion_dec->fill(mom);
            break;
          case PID::KPLUS:
            if (prompt) _histKaon_no_dec->fill(mom);
            _histKaon_dec->fill(mom);
            break;
          case PID::PROTON:
            if (prompt) _histProton_no_dec->fill(mom);
            _histProton_dec->fill(mom);
          default: break;
        }
      }
    }


    void finalize() {
      scale(_histPion_no_dec, 1. / sumOfWeights());
      scale(_histKaon_no_dec, 1. / sumOfWeights());
      scale(_histProton_no_dec, 1. / sumOfWeights());
      scale(_histPion_dec, 1. / sumOfWeights());
      scale(_histKaon_dec, 1. / sumOfWeights());
      scale(_histProton_dec, 1. / sumOfWeights());
    }


  private:

    /// @{
    // Histograms for continuum data (sqrt(s) = 10.52 GeV)
    // no K_S and Lambda decays
    Histo1DPtr _histPion_no_dec;
    Histo1DPtr _histKaon_no_dec;
    Histo1DPtr _histProton_no_dec;
    // including decays
    Histo1DPtr _histPion_dec;
    Histo1DPtr _histKaon_dec;
    Histo1DPtr _histProton_dec;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2013_I1238276);

}