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108 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief B -> phi phi K
class BABAR_2011_I901433 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2011_I901433);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
UnstableParticles ufs = UnstableParticles(Cuts::abspid==511 or
Cuts::abspid==521);
declare(ufs, "UFS");
DecayedParticles BB(ufs);
BB.addStable(PID::PHI);
BB.addStable(PID::K0S);
declare(BB, "BB");
// histograms
for(unsigned int ix=0;ix<6;++ix)
book(_h[ix],1,1,1+ix);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
DecayedParticles BB = apply<DecayedParticles>(event, "BB");
static const map<PdgId,unsigned int> & mode1 = { { 333,2},{ 321,1}};
static const map<PdgId,unsigned int> & mode1CC = { { 333,2},{-321,1}};
static const map<PdgId,unsigned int> & mode2 = { { 333,2},{ 310,1}};
for(unsigned int ix=0;ix<BB.decaying().size();++ix) {
if(BB.modeMatches(ix,3,mode1) || BB.modeMatches(ix,3,mode1CC) ||
BB.modeMatches(ix,3,mode2)) {
// phi mesons
const Particles & phi = BB.decayProducts()[ix].at(333);
// bost to B rest frane
LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(BB.decaying()[ix].momentum().betaVec());
FourMomentum pPhiPhi= boost1.transform(phi[0].momentum()+phi[1].momentum());
double mPhiPhi = pPhiPhi.mass();
int iloc=-1;
if(mPhiPhi>2.94 && mPhiPhi<3.02)
iloc=0;
else if(mPhiPhi<2.85)
iloc=3;
else continue;
// cos theta phi phi
Vector3 axis1 = pPhiPhi.p3().unit();
LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pPhiPhi.betaVec());
Vector3 axis2 = boost2.transform(boost1.transform(phi[0].momentum())).p3().unit();
_h[iloc+2]->fill(abs(axis1.dot(axis2)));
// now for the phi decays
Vector3 Trans[2];
bool foundPhi=true;
for(unsigned int ix=0;ix<2;++ix) {
if(phi[ix].children().size()!=2|| phi[ix].children()[0].pid()!=-phi[ix].children()[1].pid() ||
phi[ix].children()[0].abspid()!=321) {
foundPhi = false;
break;
}
Particle Km = phi[ix].children()[0];
Particle Kp = phi[ix].children()[1];
if(Kp.pid()<0) swap(Km,Kp);
FourMomentum pKp = boost2.transform(boost1.transform(Kp.momentum()));
FourMomentum pPhi = boost2.transform(boost1.transform(phi[ix].momentum()));
LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pPhi.betaVec());
pKp = boost3.transform(pKp);
double cK = axis2.dot(pKp.p3().unit());
_h[iloc+1]->fill(cK);
Trans[ix] = pKp.p3() - cK*pKp.p3().mod()*axis2;
}
if(!foundPhi) continue;
double chi = atan2(Trans[0].cross(Trans[1]).dot(axis2),Trans[0].dot(Trans[1]));
_h[iloc]->fill(abs(chi));
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<6;++ix)
normalize(_h[ix],1.,false);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[6];
/// @}
};
RIVET_DECLARE_PLUGIN(BABAR_2011_I901433);
}
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