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| // -*- 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_S6895344 : public Analysis {
public:
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_S6895344);
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, 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(10.58);
} else {
_histOff ->fill(xp);
_sigmaOff->fill(10.54);
}
}
}
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
Histo1DPtr _sigmaOn ;
Histo1DPtr _sigmaOff;
Histo1DPtr _histOn ;
Histo1DPtr _histOff ;
};
RIVET_DECLARE_ALIASED_PLUGIN(BABAR_2007_S6895344, BABAR_2007_I725377);
}
|