Rivet analyses

title: CLEOII_2003_I611745

Angular distributions and longitudinal polarization in $B\to D^*\rho$ decays

Experiment: CLEOII (CESR)

Inspire ID: 611745

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 67 (2003) 112002

Beams: * *

Beam energies: ANY

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

Angular distributions and longitudinal polarization in $B\to D^*\rho$ decays. The longitudinal polarizations are taken from Eqn. 3 in the paper and the angular distributions read from figure 2.

Source code:CLEOII_2003_I611745.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B -> D* rho class CLEOII_2003_I611745 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_2003_I611745);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521);
  declare(ufs, "UFS");
  DecayedParticles BB(ufs);
  BB.addStable(423);
  BB.addStable(-423);
  BB.addStable(413);
  BB.addStable(-413);
  BB.addStable(213);
  BB.addStable(-213);
  BB.addStable(113);
  declare(BB, "BB");
  // histos
  for (unsigned int ix = 0; ix < 2; ++ix) {
    for (unsigned int iy = 0; iy < 3; ++iy) {
      book(_h[ix][iy], 2, 1 + iy, 1 + ix);
      if (iy < 2) book(_p[ix][iy], "TMP/TMP_" + toString(ix) + "_" + toString(iy));
    }
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  DecayedParticles BB = apply<DecayedParticles>(event, "BB");
  // loop over particles
  for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
    int sign = BB.decaying()[ix].pid() / BB.decaying()[ix].abspid();
    unsigned int imode = 0;
    if ((BB.decaying()[ix].pid() == 521 && BB.modeMatches(ix, 2, mode1))
        || (BB.decaying()[ix].pid() == -521 && BB.modeMatches(ix, 2, mode1CC)))
      imode = 0;
    else if ((BB.decaying()[ix].pid() == 511 && BB.modeMatches(ix, 2, mode2))
             || (BB.decaying()[ix].pid() == -511 && BB.modeMatches(ix, 2, mode2CC)))
      imode = 1;
    else
      continue;
    // find D* decay products
    const Particle& Dstar = BB.decayProducts()[ix].at(-sign * (423 - 10 * imode))[0];
    if (Dstar.children().size() != 2) continue;
    Particle D0;
    int ipi = imode == 0 ? 111 : -sign * 211;
    if (Dstar.children()[0].pid() == ipi && Dstar.children()[1].abspid() == -sign * 421) {
      D0 = Dstar.children()[1];
    }
    else if (Dstar.children()[1].pid() == ipi && Dstar.children()[0].abspid() == -sign * 421) {
      D0 = Dstar.children()[0];
    }
    else {
      continue;
    }
    // rho decay products
    const Particle& rho = BB.decayProducts()[ix].at(sign * 213)[0];
    if (rho.children().size() != 2) continue;
    Particle pip;
    if (rho.children()[1].pid() == 111 && rho.children()[0].pid() == sign * 211)
      pip = rho.children()[0];
    else if (rho.children()[0].pid() == 111 && rho.children()[1].pid() == sign * 211)
      pip = rho.children()[1];
    else {
      continue;
    }
    // boost to B rest frame
    LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(
        BB.decaying()[ix].mom().betaVec());
    FourMomentum prho = boost.transform(rho.mom());
    FourMomentum pDstar = boost.transform(Dstar.mom());
    FourMomentum pPi = boost.transform(pip.mom());
    FourMomentum pD = boost.transform(D0.mom());
    const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
    pD = boost2.transform(pD);
    double cD = pD.p3().unit().dot(pDstar.p3().unit());
    Vector3 trans1 = pD.p3().unit() - cD * pDstar.p3().unit();
    _h[imode][0]->fill(cD);
    const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(prho.betaVec());
    pPi = boost3.transform(pPi);
    double cPi = pPi.p3().unit().dot(prho.p3().unit());
    Vector3 trans2 = pPi.p3().unit() - cPi * prho.p3().unit();
    _h[imode][1]->fill(cPi);
    double chi = atan2(trans1.cross(trans2).dot(prho.p3().unit()), trans1.dot(trans2));
    _h[imode][2]->fill(chi);
    _p[imode][0]->fill(-0.5 * (1 - 5 * sqr(cPi)));
    _p[imode][1]->fill();
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 2; ++ix) {
    normalize(_h[ix], 1.0, false);
    Estimate0DPtr tmp;
    book(tmp, 1, 1, 1 + ix);
    divide(*_p[ix][0], *_p[ix][1], tmp);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[2][3];
CounterPtr _p[2][2];
const map<PdgId, unsigned int> mode1 = {{-423, 1}, {213, 1}};
const map<PdgId, unsigned int> mode1CC = {{423, 1}, {-213, 1}};
const map<PdgId, unsigned int> mode2 = {{-413, 1}, {213, 1}};
const map<PdgId, unsigned int> mode2CC = {{413, 1}, {-213, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOII_2003_I611745);

} ```