Rivet analyses

B̄0 → D*+ℓ−ν̄ℓ

Experiment: ARGUS (DORIS)

Inspire ID: 267206

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 219 (1989) 121-126

Beams: * *

Beam energies: ANY

Run details: - Any process producing B mesons, originally Upsilon(4S) decays

q2 spectrum, lepton momentum spectrum and D* helicty angle in B̄0 → D*+ℓ−ν̄ℓ. Corrected data read from figure 7.

Source code:ARGUS_1989_I267206.cc

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

namespace Rivet {


  /// @brief Bbar0 -> D* l nu
  class ARGUS_1989_I267206 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1989_I267206);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
      declare(ufs, "UFS");
      DecayedParticles BB(ufs);
      BB.addStable(411);
      BB.addStable(-411);
      BB.addStable(421);
      BB.addStable(-421);
      BB.addStable(413);
      BB.addStable(-413);
      BB.addStable(423);
      BB.addStable(-423);
      BB.addStable(PID::PI0);
      declare(BB, "BB");
      // histos
      for (unsigned int ix = 0; ix < 3; ++ix) {
        book(_h[ix], 1 + ix, 1, 1);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // loop over B mesons
      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
      // loop over particles
      for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
        for (unsigned int il = 0; il < 2; ++il) {
          if (BB.modeMatches(ix, 3, mode[il])) {
            int sign = il % 2 == 0 ? -1 : 1;
            const Particle& DD = BB.decayProducts()[ix].at(sign * 413)[0];
            const Particle& em = BB.decayProducts()[ix].at(sign * 11)[0];
            FourMomentum qq = BB.decaying()[ix].mom() - DD.mom();
            _h[1]->fill(em.mom().p3().mod());
            _h[2]->fill(qq.mass2());
            if (DD.children().size() != 2) continue;
            // boost to B rest frame
            LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(
                BB.decaying()[ix].mom().betaVec());
            FourMomentum pDD = boost1.transform(DD.mom());
            Particle D0;
            if (DD.children()[0].pid() == sign * 211 && DD.children()[1].pid() == sign * 421) {
              D0 = DD.children()[1];
            }
            else if (DD.children()[1].pid() == sign * 211 && DD.children()[0].pid() == sign * 421) {
              D0 = DD.children()[0];
            }
            else {
              continue;
            }
            FourMomentum pD0 = boost1.transform(D0.mom());
            LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pDD.betaVec());
            pD0 = boost3.transform(pD0);
            double cTheta = pD0.p3().unit().dot(pDD.p3().unit());
            _h[0]->fill(cTheta);
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h, 1.0, false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[3];
    const map<PdgId, unsigned int> mode[2] = {{{-413, 1}, {-11, 1}, {12, 1}}, {{413, 1}, {11, 1}, {-12, 1}}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(ARGUS_1989_I267206);

}