Rivet analyses
Measurement of angular asymmetries in the decays B → K*ℓ+ℓ−
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 → K*ℓ+ℓ−
Source
code:BABAR_2016_I1391152.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.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);
}