Rivet analyses

title: BELLE_2016_I1504055

Angular Analysis of $B\to K^{*}\ell^-\ell^-$

Experiment: BELLE (KEKB)

Inspire ID: 1504055

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 118 (2017) 11, 111801

Beams: * *

Beam energies: ANY

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

Measurement of angular coefficients in $B\to K^{*}\ell^-\ell^-$, the code implements these by taking appropriate moments

Source code:BELLE_2016_I1504055.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 BELLE_2016_I1504055 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2016_I1504055);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 or 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");
  for (unsigned int ix = 0; ix < 2; ++ix) {
    for (unsigned int iy = 0; iy < 6; ++iy) {
      book(_p_P[ix][iy], "TMP/p_P_" + toString(ix) + "_" + toString(iy), refData(1, 1 + ix, 1 + iy));
      if (iy > 1) continue;
      book(_p_Q[ix][iy], "TMP/p_Q_" + toString(ix) + "_" + toString(iy), refData(2, 1 + ix, 1 + iy));
    }
  }
  book(_FL, "TMP/FL");
  book(_norm, "TMP/norm");
}


/// 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)
        KK = Kstar.children()[0];
      else if (Kstar.children()[1].abspid() == 321 && Kstar.children()[0].abspid() == 111)
        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);
    Vector3 axis1 = boost.transform(pB).p3().unit();
    double cThetaL = plp.p3().unit().dot(axis1);
    Vector3 Trans1 = plp.p3() - cThetaL * plp.p3().mod() * axis1;
    // kaon stuff
    const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
    pK = boost3.transform(pK);
    Vector3 axis2 = boost.transform(pB).p3().unit();
    double cThetaK = pK.p3().unit().dot(axis2);
    double FL = .5 * (5. * sqr(cThetaK) - 1.);
    Vector3 Trans2 = pK.p3() - cThetaK * pK.p3().mod() * axis2;
    double phi = atan2(Trans1.cross(Trans2).dot(axis2), Trans1.dot(Trans2));
    double sThetaL = sqrt(1. - sqr(cThetaL));
    double sThetaK = sqrt(1. - sqr(cThetaK));
    double S4 = 12.5 * cThetaL * sThetaL * cThetaK * sThetaK * cos(phi);
    double S5 = 5. * cThetaK * sThetaK * sThetaL * sin(phi);
    _FL->fill(FL);
    _norm->fill();
    for (unsigned int ix = 0; ix < 2; ++ix) {
      _p_P[ix][0]->fill(qq, S4);
      _p_P[ix][3]->fill(qq, S5);
      if (il == 11) {
        _p_P[ix][1]->fill(qq, S4);
        _p_P[ix][4]->fill(qq, S5);
        _p_Q[ix][0]->fill(qq, -S4);
        _p_Q[ix][1]->fill(qq, -S5);
      }
      else {
        _p_P[ix][2]->fill(qq, S4);
        _p_P[ix][5]->fill(qq, S5);
        _p_Q[ix][0]->fill(qq, S4);
        _p_Q[ix][1]->fill(qq, S5);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  Estimate0D R = *_FL / *_norm;
  double fl = R.val();
  double fact = 1. / sqrt(fl * (1. - fl));
  for (unsigned int ix = 0; ix < 2; ++ix) {
    for (unsigned int iy = 0; iy < 6; ++iy) {
      Estimate1DPtr tmp;
      book(tmp, 1, 1 + ix, 1 + iy);
      barchart(_p_P[ix][iy], tmp);
      scale(tmp, fact);
      if (iy > 1) continue;
      book(tmp, 2, 1 + ix, 1 + iy);
      barchart(_p_Q[ix][iy], tmp);
      scale(tmp, fact);
    }
  }
}

/// @}


/// @name Histograms
/// @{
Profile1DPtr _p_P[2][6], _p_Q[2][2];
CounterPtr _FL, _norm;
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2016_I1504055);

} ```