Rivet analyses

title: BABAR_2006_I713862

$\bar{B}^0\to D^{*+} \omega\pi^-$ decays

Experiment: BABAR (PEP-II)

Inspire ID: 713862

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 74 (2006) 012001

Beams: * *

Beam energies: ANY

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

Measurement of mass distributions and the $D^{+}$ polarization in $\bar{B}^0\to D^{+} \omega\pi^-$ decays. The background subtracted/corrected data for the mass distributions was read from the figures in the paper and the polarization from Table 1.

Source code:BABAR_2006_I713862.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Bbar0 -> D*+ omega pi- class BABAR_2006_I713862 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2006_I713862);


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

/// Book histograms and initialise projections before the run
void init() {
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
  declare(ufs, "UFS");
  DecayedParticles BB(ufs);
  BB.addStable(PID::PI0);
  BB.addStable(413);
  BB.addStable(-413);
  BB.addStable(223);
  declare(BB, "BB");
  // histos
  for (unsigned int ix = 0; ix < 2; ++ix) book(_h[ix], 1 + ix, 1, 1);
  book(_p, 3, 1, 1);
  book(_c, "TMP/nB");
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode1 = {{-413, 1}, {211, 1}, {223, 1}};
  static const map<PdgId, unsigned int>& mode1CC = {{413, 1}, {-211, 1}, {223, 1}};
  // loop over particles
  DecayedParticles BB = apply<DecayedParticles>(event, "BB");
  for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
    _c->fill();
    int sign = BB.decaying()[ix].pid() / BB.decaying()[ix].abspid();
    if ((sign == 1 && BB.modeMatches(ix, 3, mode1)) || (sign == -1 && BB.modeMatches(ix, 3, mode1CC))) {
      const Particle& omega = BB.decayProducts()[ix].at(223)[0];
      const Particle& pim = BB.decayProducts()[ix].at(sign * 211)[0];
      const Particle& Dstar = BB.decayProducts()[ix].at(-sign * 413)[0];
      double mX = (omega.momentum() + pim.momentum()).mass();
      _h[0]->fill(sqr(mX));
      if (Dstar.children().size() != 2) continue;
      // boost to B rest frame
      LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(
          BB.decaying()[ix].momentum().betaVec());
      FourMomentum pDpi = boost1.transform(Dstar.momentum() + pim.momentum());
      LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDpi.betaVec());
      FourMomentum pDstar = boost2.transform(boost1.transform(Dstar.momentum()));
      double c1 = pDstar.p3().unit().dot(pDpi.p3().unit());
      if (c1 < 0.5) _h[1]->fill(pDpi.mass());
      Particle D0;
      if (Dstar.children()[0].pid() == -sign * 211 && Dstar.children()[1].abspid() == -sign * 421)
        D0 = Dstar.children()[1];
      else if (Dstar.children()[1].pid() == -sign * 211 && Dstar.children()[0].abspid() == -sign * 421)
        D0 = Dstar.children()[0];
      else
        continue;
      FourMomentum pD0 = boost2.transform(boost1.transform(D0.momentum()));
      LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
      pD0 = boost3.transform(pD0);
      double cTheta = pD0.p3().unit().dot(pDstar.p3().unit());
      _p->fill(mX, .5 * (5. * sqr(cTheta) - 1.));
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // first hist is differential BR/ BR for leptons
  double br = .1033;
  scale(_h[0], 1. / br / *_c);
  normalize(_h[1], 1., false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[2];
Profile1DPtr _p;
CounterPtr _c;
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2006_I713862);

} ```