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/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.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);
}