Rivet analyses
Angular Analysis of B → K*ℓ−ℓ−
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 → K*ℓ−ℓ−, the code implements these by taking appropriate moments
Source
code:BELLE_2016_I1504055.cc
// -*- 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);
}