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Rivet analyses reference
BELLE_2009_I803343
Mass and angular distributions in $B\to\Lambda^0\bar\Lambda^0 K^{(*)}$
Experiment: BELLE (KEKB)
Inspire ID: 803343
Status: VALIDATED NOHEPDATA
Authors:
References:
- Phys.Rev.D 79 (2009) 052006
Beams: * *
Beam energies: ANY
Run details:
- Any process producing B0, originally Upsilon(4S) decay
Measurement of mass and angular distributions in $B^0\to\Lambda^0\bar\Lambda^0 K^0$, $B^+\to\Lambda^0\bar\Lambda^0 K^+$ and $B^0\to\Lambda^0\bar\Lambda^0 K^{*0}$. The data for the mass spectra was read from the tables in the paper and are fully corrected, while those for the angular distributions in the threshold region were read from the figures and may not be corrected.
Source code:
BELLE_2009_I803343.cc
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153 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief B0 -> Lambda Lambdabar K(*)0
class BELLE_2009_I803343 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2009_I803343);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::pid==511 ||
Cuts::pid==521);
declare(ufs, "UFS");
DecayedParticles BB(ufs);
BB.addStable( 3122);
BB.addStable(-3122);
BB.addStable( 310);
BB.addStable( 313);
BB.addStable(-313);
declare(BB, "BB");
// histograms
for(unsigned int ix=0;ix<3;++ix) {
book(_h_mass[ix],1,1,1+ix);
book(_h_angle[ix],2+ix,1,1);
}
book(_c[0],"TMP/nB0");
book(_c[1],"TMP/nBP");
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode1 = { { 3122,1},{-3122,1}, { 310,1}};
static const map<PdgId,unsigned int> & mode2 = { { 3122,1},{-3122,1}, { 321,1}};
static const map<PdgId,unsigned int> & mode2CC = { { 3122,1},{-3122,1}, {-321,1}};
static const map<PdgId,unsigned int> & mode3 = { { 3122,1},{-3122,1}, { 313,1}};
static const map<PdgId,unsigned int> & mode3CC = { { 3122,1},{-3122,1}, {-313,1}};
DecayedParticles BB = apply<DecayedParticles>(event, "BB");
// loop over particles
for(unsigned int ix=0;ix<BB.decaying().size();++ix) {
if(BB.decaying()[ix].abspid()==511) _c[0]->fill();
else _c[1]->fill();
unsigned int imode=0;
if (BB.modeMatches(ix,3,mode1))
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
continue;
int sign = BB.decaying()[ix].pid()>0 ? 1 : -1;
const Particle & Lam = BB.decayProducts()[ix].at( sign*3122)[0];
const Particle & LamBar = BB.decayProducts()[ix].at(-sign*3122)[0];
FourMomentum pLL = Lam.momentum()+LamBar.momentum();
double mass = pLL.mass();
_h_mass[imode]->fill(mass);
// rest just in threshold region
if(mass>2.85) continue;
// boost to B rest frame
LorentzTransform boost =
LorentzTransform::mkFrameTransformFromBeta(BB.decaying()[ix]. momentum().betaVec());
// B+ K+
if(imode==1) {
pLL = boost.transform(pLL);
LorentzTransform boost2 =
LorentzTransform::mkFrameTransformFromBeta(pLL.betaVec());
FourMomentum pLam = boost2.transform(boost.transform(Lam.momentum()));
FourMomentum pLamB = boost2.transform(boost.transform(LamBar.momentum()));
const Particle & Kp = BB.decayProducts()[ix].at( sign*321)[0];
FourMomentum pK = boost2.transform(boost.transform(Kp.momentum()));
double cLam = pK.p3().unit().dot(pLamB.p3().unit());
_h_angle[1]->fill(cLam);
if(Lam.children().size()==2) {
Particle proton;
if(Lam.children()[0].pid()== sign*2212 &&
Lam.children()[1].pid()==-sign*211 ) {
proton = Lam.children()[0];
}
else if(Lam.children()[1].pid()== sign*2212 &&
Lam.children()[0].pid()==-sign*211 ){
proton = Lam.children()[1];
}
if(proton.pid()==sign*2212) {
LorentzTransform boostL = LorentzTransform::mkFrameTransformFromBeta(pLam.betaVec());
FourMomentum pp = boostL.transform(boost2.transform(boost.transform(proton.momentum())));
double cTheta = pp.p3().unit().dot(pLam.p3().unit());
_h_angle[0]->fill(cTheta);
}
}
}
// B0 -> K*0
else if(imode==2) {
const Particle & Kstar = BB.decayProducts()[ix].at( sign*313)[0];
Particle KK;
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;
FourMomentum pKstar = boost.transform(Kstar.momentum());
FourMomentum pK = boost.transform(KK .momentum());
const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
pK = boost3.transform(pK);
FourMomentum pB = boost3.transform(boost.transform(BB.decaying()[ix].momentum()));
double cosK = -pB.p3().unit().dot(pK.p3().unit());
_h_angle[2]->fill(cosK);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<3;++ix) {
if(ix%2==0) scale(_h_mass[ix],1e6/ *_c[0]);
else scale(_h_mass[ix],1e6/ *_c[1]);
normalize(_h_angle[ix]);
}
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_mass[3],_h_angle[3];
CounterPtr _c[2];
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2009_I803343);
}
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