// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief B -> Xs l+l-
class BELLE_2016_I1283183 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2016_I1283183);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(Cuts::abspid==521 || Cuts::abspid==511), "UFS");
// book the profile hist
book(_p,2,1,1);
}
void findDecayProducts(bool & charm, const Particle& mother,
unsigned int& nK0, unsigned int& nKp,
unsigned int& nKm, Particles & lp, Particles & lm) {
for (const Particle & p : mother.children()) {
int id = p.pid();
if(PID::isCharmHadron(p.pid())) charm = true;
else if ( id == PID::POSITRON || id == PID::ANTIMUON) lp.push_back(p);
else if ( id == PID::ELECTRON || id == PID::MUON ) lm.push_back(p);
else if ( id == PID::KPLUS ) ++nKp;
else if (id == PID::KMINUS ) ++nKm;
else if (id == PID::K0S) ++nK0;
else if (id == PID::PI0 || id == PID::PIPLUS || id == PID::PIMINUS) {
continue;
}
else if ( !p.children().empty() ) {
findDecayProducts(charm, p, nK0, nKp, nKm,lp,lm);
}
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Loop over bottoms
for (const Particle& bottom : apply<UnstableParticles>(event, "UFS").particles()) {
// remove mixing entries etc
if(bottom.children()[0].abspid()==bottom.abspid()) continue;
bool charm = false;
Particles lp,lm;
unsigned int nK0(0),nKp(0),nKm(0);
findDecayProducts(charm,bottom, nK0, nKp, nKm,lp,lm);
if(charm) continue;
unsigned int nk = nKp-nKm+nK0;
if( nk % 2 == 0) continue;
if (lp.size()!=1 || lm.size()!=1 || lp[0].pid()!=-lm[0].pid()) continue;
if(bottom.pid()>0) swap(lp,lm);
double q2 = (lp[0].momentum()+lm[0].momentum()).mass2();
// veto region valid for muons but not electrons
if(lm[0].pid()==PID::ELECTRON && ( (q2>7.3 && q2<8.1) || (q2>11.8 && q2<12.5) )) continue;
// first boost to bottom frame
const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(bottom.momentum().betaVec());
FourMomentum plp = boost.transform(lp[0] .momentum());
FourMomentum plm = boost.transform(lm[0] .momentum());
FourMomentum pB = boost.transform(bottom.momentum());
const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta((plp+plm).betaVec());
plp = boost2.transform(plp);
pB = boost .transform(pB );
double cTheta = plp.p3().unit().dot(pB.p3().unit());
_p->fill(q2, cTheta>0 ? 1 : -1);
}
}
/// Normalise histograms etc., after the run
void finalize() {
}
/// @}
/// @name Histograms
/// @{
Profile1DPtr _p;
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2016_I1283183);
}