Rivet analyses

title: BABAR_2016_I1391152

Measurement of angular asymmetries in the decays $B\to K^*\ell^+\ell^-$

Experiment: BABAR (PEP-II)

Inspire ID: 1391152

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.D 93 (2016) 5, 052015

Beams: * *

Beam energies: ANY

Run details: - Any process producing B+ and B0, originally Upsilon(4S) decay

Measurement of angular asymmetries in the decays $B\to K^*\ell^+\ell^-$

Source code:BABAR_2016_I1391152.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B -> K* l+l- class BABAR_2016_I1391152 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2016_I1391152);


/// @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(443);
  BB.addStable(100443);
  BB.addStable(313);
  BB.addStable(323);
  BB.addStable(-313);
  BB.addStable(-323);
  declare(BB, "BB");
  // book histograms
  for (unsigned int ix = 0; ix < 2; ++ix) {
    for (unsigned int iy = 0; iy < 3; ++iy) {
      book(_p_FL[ix][iy], 1, 1 + ix, 1 + iy);
      book(_p_FB[ix][iy], 2, 1 + ix, 1 + iy);
      book(_p_P2_num[ix][iy], "TMP/P2_num_" + toString(ix + 1) + "_" + toString(iy + 1),
           refData(3, 1 + ix, 1 + iy));
      book(_p_P2_den[ix][iy], "TMP/P2_den_" + toString(ix + 1) + "_" + toString(iy + 1),
           refData(3, 1 + ix, 1 + iy));
    }
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode1 = {{323, 1}, {13, 1}, {-13, 1}};
  static const map<PdgId, unsigned int>& mode1CC = {{-323, 1}, {13, 1}, {-13, 1}};
  static const map<PdgId, unsigned int>& mode2 = {{313, 1}, {13, 1}, {-13, 1}};
  static const map<PdgId, unsigned int>& mode2CC = {{-313, 1}, {13, 1}, {-13, 1}};
  static const map<PdgId, unsigned int>& mode3 = {{323, 1}, {11, 1}, {-11, 1}};
  static const map<PdgId, unsigned int>& mode3CC = {{-323, 1}, {11, 1}, {-11, 1}};
  static const map<PdgId, unsigned int>& mode4 = {{313, 1}, {11, 1}, {-11, 1}};
  static const map<PdgId, unsigned int>& mode4CC = {{-313, 1}, {11, 1}, {-11, 1}};
  DecayedParticles BB = apply<DecayedParticles>(event, "BB");
  // loop over particles
  for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
    int imode = 0;
    if ((BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode1))
        || (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode1CC)))
      imode = 0;
    else if ((BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode2))
             || (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode2CC)))
      imode = 1;
    else if ((BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode3))
             || (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode3CC)))
      imode = 2;
    else if ((BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode4))
             || (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode4CC)))
      imode = 3;
    else
      continue;
    int il = imode < 2 ? 13 : 11;
    int sign = BB.decaying()[ix].pid() > 0 ? 1 : -1;
    const Particle& lp = BB.decayProducts()[ix].at(-sign * il)[0];
    const Particle& lm = BB.decayProducts()[ix].at(sign * il)[0];
    double qq = (lp.momentum() + lm.momentum()).mass2();
    int iK = BB.decaying()[ix].abspid() == 521 ? 323 : 313;
    iK *= BB.decaying()[ix].pid() / BB.decaying()[ix].abspid();
    const Particle& Kstar = BB.decayProducts()[ix].at(iK)[0];
    if (Kstar.children().size() != 2) continue;
    Particle KK;
    if (Kstar.abspid() == 313) {
      if (Kstar.children()[0].abspid() == 321 && Kstar.children()[1].abspid() == 211)
        KK = Kstar.children()[0];
      else if (Kstar.children()[1].abspid() == 321 && Kstar.children()[0].abspid() == 211)
        KK = Kstar.children()[1];
      else
        continue;
    }
    else {
      if (Kstar.children()[0].abspid() == 311 && Kstar.children()[1].abspid() == 211)
        KK = Kstar.children()[0];
      else if (Kstar.children()[1].abspid() == 311 && Kstar.children()[0].abspid() == 211)
        KK = Kstar.children()[1];
      else if (Kstar.children()[0].abspid() == 310 && Kstar.children()[1].abspid() == 211)
        KK = Kstar.children()[0];
      else if (Kstar.children()[1].abspid() == 310 && Kstar.children()[0].abspid() == 211)
        KK = Kstar.children()[1];
      else if (Kstar.children()[0].abspid() == 321 && Kstar.children()[1].abspid() == 111 && il == 11)
        KK = Kstar.children()[0];
      else if (Kstar.children()[1].abspid() == 321 && Kstar.children()[0].abspid() == 111 && il == 11)
        KK = Kstar.children()[1];
      else
        continue;
      if (KK.abspid() == 311) {
        if (KK.children().size() == 1 && KK.children()[0].pid() == 310)
          KK = KK.children()[0];
        else
          continue;
      }
    }
    // first boost to bottom frame
    const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(
        BB.decaying()[ix].momentum().betaVec());
    FourMomentum plp = boost.transform(lp.momentum());
    FourMomentum plm = boost.transform(lm.momentum());
    FourMomentum pKstar = boost.transform(Kstar.momentum());
    FourMomentum pK = boost.transform(KK.momentum());
    FourMomentum pB = boost.transform(BB.decaying()[ix].momentum());
    // lepton stuff
    const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta((plp + plm).betaVec());
    plp = boost2.transform(plp);
    double cTheta = plp.p3().unit().dot(boost.transform(pB).p3().unit());
    double AFB = cTheta > 0 ? 1 : -1;
    // kaon stuff
    const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
    pK = boost3.transform(pK);
    cTheta = pK.p3().unit().dot(boost.transform(pB).p3().unit());
    double FL = .5 * (5. * sqr(cTheta) - 1.);
    // fill histograms
    for (unsigned int iz = 0; iz < 2; ++iz) {
      for (unsigned int iy = 0; iy < 3; ++iy) {
        if ((BB.decaying()[ix].abspid() == 511 && iy == 0)
            || (BB.decaying()[ix].abspid() == 521 && iy == 1))
          continue;
        _p_FB[iz][iy]->fill(qq, AFB);
        _p_FL[iz][iy]->fill(qq, FL);
        _p_P2_num[iz][iy]->fill(qq, -2. / 3. * AFB);
        _p_P2_den[iz][iy]->fill(qq, 1. - FL);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 2; ++ix) {
    for (unsigned int iy = 0; iy < 3; ++iy) {
      Estimate1DPtr tmp;
      book(tmp, 3, 1 + ix, 1 + iy);
      divide(_p_P2_num[ix][iy], _p_P2_den[ix][iy], tmp);
    }
  }
}

/// @}


/// @name Histograms
/// @{
Profile1DPtr _p_FL[2][3], _p_FB[2][3], _p_P2_num[2][3], _p_P2_den[2][3];
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2016_I1391152);

} ```