Rivet analyses

title: BABAR_2007_I725377

Inclusive $\Lambda_c^+$ Production in $e^+e^-$ Annihilation at $\sqrt{s}=10.54$ GeV and in $\Upsilon(4S)$ Decays.

Experiment: BaBar (PEP-II)

Inspire ID: 725377

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D75 (2007) 012003 - hep-ex/0609004

Beams: e+ e-

Beam energies: (3.5, 8.0); (3.5, 7.9)GeV

Run details: - $e^+ e^-$ analysis on the $\Upsilon(4S)$ resonance, with CoM boosts of 8.0~GeV~($e^-$) and 3.5~GeV~($e^+$)

Measurements of the total production rates and momentum distributions of the charmed baryon $\Lambda_c^+$ in $e^+e^- \to$ hadrons at a centre-of-mass energy of 10.54 GeV and in $\Upsilon(4S)$ decays.

Source code:BABAR_2007_I725377.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief BABAR Lambda_c from fragmentation /// /// @author Peter Richardson class BABAR_2007_I725377 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I725377);


void init() {
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");

  book(_histOff, 1, 1, 1);
  book(_sigmaOff, 2, 1, 1);
  book(_histOn, 3, 1, 1);
  book(_sigmaOn, 4, 1, 1);
}


void analyze(const Event& e) {
  // Loop through unstable FS particles and look for charmed mesons/baryons
  const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");

  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());
  const double s = sqr(beamproj.sqrtS());
  const bool onresonance = fuzzyEquals(beamproj.sqrtS(), 10.58 * GeV, 2E-3);

  // Particle masses from PDGlive (accessed online 16. Nov. 2009).
  for (const Particle& p : ufs.particles()) {
    // Only looking at Lambda_c
    if (p.abspid() != 4122) continue;
    MSG_DEBUG("Lambda_c found");
    const double mH2 = 5.22780; // 2.28646^2
    const double mom = FourMomentum(cms_boost.transform(p.momentum())).p();
    const double xp = mom / sqrt(s / 4.0 - mH2);

    if (onresonance) {
      _histOn->fill(xp);
      _sigmaOn->fill(Ecm);
    }
    else {
      _histOff->fill(xp);
      _sigmaOff->fill(0.5);
    }
  }
}


void finalize() {
  scale(_sigmaOn, 1. / sumOfWeights());
  scale(_sigmaOff, 1. / sumOfWeights());
  scale(_histOn, 1. / sumOfWeights());
  scale(_histOff, 1. / sumOfWeights());
}

private:

// Histograms for the continuum cross sections
BinnedHistoPtr<string> _sigmaOn;
Histo1DPtr _sigmaOff;
Histo1DPtr _histOn;
Histo1DPtr _histOff;
const string Ecm = "10.58";

};

RIVET_DECLARE_ALIASED_PLUGIN(BABAR_2007_I725377, BABAR_2007_S6895344);

} ```

Aliases: - BABAR_2007_S6895344