Rivet analyses

Baryon spectra in e+e− collisions at 10.52 GeV

Experiment: BELLE (KEKB)

Inspire ID: 1606201

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D97 (2018) no.7, 072005

Beams: e- e+

Beam energies: (5.3, 5.3)GeV

Run details: - e+ e- to hadrons and e+ e-

Measurement of spectra for hyperon and charm baryon production in e+e− collisions at 10.52 GeV by BELLE. The spectra for Λ0, Σ0, Σ*+, Λ0(1520), Ξ−, Ω− and Ξ*0 hyperons are measured. The spectra for the Λc+, Λc(2595)+, Λc(2625)+, Σc(2455)0, Σc(2520)0, Ωc0 and Ξc0 charm baryons are also measured.

Source code:BELLE_2017_I1606201.cc

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

namespace Rivet {


  /// @brief baryon rates and spectra
  class BELLE_2017_I1606201 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2017_I1606201);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      // Book histograms
      for (unsigned int ix = 1; ix < 16; ++ix) {
        book(_h[ix], ix, 1, 1);
        book(_r[ix], 16, 1, ix);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

      for (const Particle& p : ufs.particles()) {
        const Vector3 mom3 = p.p3();
        double pp = mom3.mod();
        double xp = pp / sqrt(0.25 * sqr(sqrtS()) - sqr(p.mass()));
        int id = abs(p.pid());
        if (id == 3122) {
          _h[1]->fill(xp);
          _r[1]->fill(0.5);
        }
        else if (id == 3212) {
          _h[2]->fill(xp);
          _r[2]->fill(0.5);
        }
        else if (id == 3224) {
          _h[3]->fill(xp);
          _r[3]->fill(0.5);
        }
        else if (id == 102134) {
          _h[4]->fill(xp);
          _r[4]->fill(0.5);
        }
        else if (id == 3312) {
          _h[5]->fill(xp);
          _r[5]->fill(0.5);
        }
        else if (id == 3334) {
          _h[6]->fill(xp);
          _r[6]->fill(0.5);
        }
        else if (id == 3324) {
          _h[7]->fill(xp);
          _r[7]->fill(0.5);
        }
        else if (id == 4122) {
          _h[8]->fill(xp);
          _r[8]->fill(0.5);
        }
        else if (id == 102142) {
          _h[9]->fill(xp);
          _r[9]->fill(0.5);
        }
        else if (id == 102144) {
          _h[10]->fill(xp);
          _r[10]->fill(0.5);
        }
        else if (id == 4112) {
          _h[11]->fill(xp);
          _r[11]->fill(0.5);
        }
        else if (id == 4114) {
          _h[12]->fill(xp);
          _r[12]->fill(0.5);
        }
        else if (id == 4332) {
          if (isDecay(p, {3334, -211})) {
            _h[13]->fill(xp);
            _r[13]->fill(0.5);
          }
        }
        else if (id == 4132) {
          if (isDecay(p, {3312, 211})) {
            _h[14]->fill(xp);
            _r[14]->fill(0.5);
          }
          else if (isDecay(p, {3334, 321})) {
            _h[15]->fill(xp);
            _r[15]->fill(0.5);
          }
        }
      }
    }

    // Check for explicit decay into pdgids
    bool isDecay(const Particle& mother, vector<int> ids) {
      if (mother.pid() < 0) {
        for (unsigned int ix = 0; ix < ids.size(); ++ix) ids[ix] *= -1;
      }
      // Trivial check to ignore any other decays but the one in question modulo photons
      const Particles children = mother.children(Cuts::pid != PID::PHOTON);
      if (children.size() != ids.size()) return false;
      // Check for the explicit decay
      return all(ids, [&](int i) { return count(children, hasPID(i)) == 1; });
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      // norm to cross section
      for (unsigned int ix = 1; ix < 16; ++ix) {
        if (ix <= 4 || (ix >= 8 && ix <= 12))
          scale(_h[ix], crossSection() / nanobarn / sumOfWeights());
        else
          scale(_h[ix], crossSection() / picobarn / sumOfWeights());
        scale(_r[ix], crossSection() / picobarn / sumOfWeights());
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[16], _r[16];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2017_I1606201);


}