LoKiGenParticleFunctions < LHCb

LHCb Web>LHCbComputing>LoKi>LoKiLUG>LoKiRefMan>LoKiGenParticleFunctions (2013-12-15, AlexN) (raw view)
---+!! LoKi's Generator (HepMC) Particle Functions

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%TOC% 

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---+++ ==G3Q==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_three_charge.html][LoKi::GenParticles::ThreeCharge()]]=

The simple function  which returns the triple charge of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle* p = ... ;
const double q3 = G3Q ( p ) ;
%ENDSYNTAX%


---+++ ==GABSID==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_abs_identifier.html][LoKi::GenParticles::AbsIdentifier()]]=


The simple function  which returns the absolute value of PDG-identifier of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle* p = ... ;
const double absid = GABSID( p ) ;
%ENDSYNTAX%
The special equality/non-equality [[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/_gen_p_i_d_operators_8h.html][operators]]
against  =std::string= and =LHCb::ParticleID= objects are defined:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GRange kaons = gselect ( "kaons" , "K+" == GABSID ) ; 
GRange nonmuons = gselect ( "!mu" , LHCb::ParticleID( 13 ) != GABSID ) ;
%ENDSYNTAX%
See also [[#LoKiCutsGID][GID]].


#LoKiCutsGALL
---+++ ==GALL==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/struct_lo_ki_1_1_boolean_constant.html][LoKi::BooleanConstant&lt;const HepMC::GenParticle*&gt;(true)]]=
The most trivial _"select-all"_ predicate which always returns ==true==

---+++ ==GANCESTOR==, C++ type 
=[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_an_ancestor.html][LoKi::GenParticles::IsAnAncestor]]=

The predicate which evaluates for =true= for all  'ancestors' of given particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle bquark = ... ;
     
// get all particles from b-quark 
typedef std::vector<const HepMC::GenParticle*> GPs ;
GPs gps ;
const LHCb::HepMCEvents* events = ... ;
LoKi::Extract::genParticles 
                      (  events                     ,   // source  
                         std::back_inserter ( gps ) ,   // target 
                         GANCESTOR ( bquark )      ) ; // predicate    
      
%ENDSYNTAX%

#LoKiCutsGBAR
---+++ ==GBAR==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_bar_code.html][LoKi::GenParticles:BarCode()]]=
Simple function which returns the _bar-code_ of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GRange one = gselect ( "One" , 1 == BAR ) ;
%ENDSYNTAX%

---+++ ==GBARCODE==
It is an alias for =GBAR=, see [[#LoKiCutsGBAR][GBAR]]


---+++ ==GBARYON==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_baryon.html][LoKi::GenParticles::IsBaryon()]]=
 
Simple predicate which returns =true= for baryons
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all  beuaty baryons
GRange good = gselect ( "good" ,  GBARYON && GBEAUTY )  ;
%ENDSYNTAX%


---+++ ==GBEAUTY==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_has_quark.html][LoKi::GenParticles::HasQuark(LHCb::ParticleID::bottom)]]=
 
Simple predicate which checks the presence of beauty quark:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select energetic beauty particles
GRange good = gselect ( "good" ,  GBEAUTY && GPT > 1 * GeV )  ;
%ENDSYNTAX%

---+++ ==GCHARGED==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_charged.html][LoKi::GenParticles::IsCharged()]]=
 
Simple predicate which checks the charge of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all charged msons 
GRange good = gselect ( "mesons" ,  GMESON && GCHARGED )  ;
%ENDSYNTAX%

---+++ ==GCHARM==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_has_quark.html][LoKi::GenParticles::HasQuark(LHCb::ParticleID::charm)]]=
 
Simple predicate which checks the presence of charm quark:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select energetic charm particles
GRange good = gselect ( "good" ,  GCHARM && GPT > 1 * GeV )  ;
%ENDSYNTAX%

---+++ ==GE==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_energy.html][LoKi::GenParticles::Energy()]]=
 
The function which returns the transverse momenum of the particle: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all fast particles only:
GRange fast  = gselect ( "fast" ,  GE > 50 * GeV  )  ;
%ENDSYNTAX%

---+++ ==GETA==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_pseudo_rapidity.html][LoKi::GenParticles::PseudoRapidity()]]=
 
Simple function which evaluates pseudorapidity, <latex>\eta</latex>, of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GRange inAcc = gselect ( "inAcc" , 5 > GETA &&  GETA > 2  ) ; 
%ENDSYNTAX%

---+++ ==GDELTAR2==
It is an alias for =GDR2=, see [[#LoKiCutsGDR2][GDR2]]

---+++ ==GDETA==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_delpa_eta.html][LoKi::GenParticles::DeltaEta]]=
 
Simple function which evaluates the difference in the pseudorapidity <latex>\eta</latex> with respect to some
reference value <latex>\eta_0</latex>:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle* p = ... ;
const Gaudi::LorentzVector& v = ... ;
Fun deta = GDETA( v ) ;
const double result = deta ( p ) ;
%ENDSYNTAX%

---+++ ==GDPHI==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_delpa_phi.html][LoKi::GenParticles::DeltaPhi]]=
 
Simple function which evaluates the difference in the azimuthal angle <latex>\phi</latex> with respect to some
reference value <latex>\phi_0</latex>:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle* p = ... ;
const Gaudi::LorentzVector& v = ... ;
Fun dphi = GDPHI( v ) ;
const double result = dphi ( p ) ;
%ENDSYNTAX%

#LoKiCutsGDR2
---+++ ==GDR2==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_delta_r2.html][LoKi::GenParticles::DeltaR2]]=
 
Simple function which evaluates <latex>\sqrt{ \Delta\phi^2 + \Delta\eta^2}</latex>
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle* p = ... ;
const Gaudi::LorentzVector& v = ... ;
Fun dr2 = GDR2( v.Phi() ) ;
const double result = dr2 ( p ) ;
%ENDSYNTAX%


---+++ ==GFALSE==
It is an alias for =GNONE=, see [[#LoKiCutsGNONE][GNONE]]

---+++ ==GFAPVX==, C++ type C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_adapter_to_production_vertex.html][LoKi::GenParticles::AdapterToProductionVertex]]=

The helper adapter which delegates the evaluation of the _"vertex"_ function to _production vertex_ of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
/// Extract all particles, which are produces at |z|<10 
const LHCb::HepMCEvents* events 
  get<LHCb::HepMCEvents>( LHCb::HepMCEventLocation::Default ) ;

typedef std::vector<HepMC::GenParticle*> PARTICLES ;
PARTICLES parts ;

// create the predicate:
GCut cut = GFAPVX( abs( GVZ  ) , 0 )  < 10 ;
LoKi::Extract::genParticles ( events , std::back_inserter ( parts )  , cut ) ;

%ENDSYNTAX%

---+++ ==GFAEVX==, C++ type C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_adapter_to_end_vertex.html][LoKi::GenParticles::AdapterToEndVertex]]=

The helper adapter which delegates the evaluation of the _"vertex"_ function to _end-vertex_ of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
/// Extract all particles, which are decayed after  |z|>1*meter 
const LHCb::HepMCEvents* events 
  get<LHCb::HepMCEvents>( LHCb::HepMCEventLocation::Default ) ;

typedef std::vector<HepMC::GenParticle*> PARTICLES ;
PARTICLES parts ;

// create the predicate:
GCut cut = GFAEVX( abs( GVZ  ) , 0 )  >  1 * meter ;
LoKi::Extract::genParticles ( events , std::back_inserter ( parts )  , cut ) ;

%ENDSYNTAX%

---+++ ==GFROMTREE==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_from_hep_m_c_tree.html][LoKi::GenParticles::FromHepMCTree]]=

The predicate which evaluates for =true= for all particles which belongs to "descendants" 
of the given particle/vertex 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%

const HepMC::GenParticle bquark = ... ;

// get all particles from b-quark 
typedef std::vector<const HepMC::GenParticle*> GPs ;
GPs gps ;
const LHCb::HepMCEvents* events = ... ;
LoKi::Extract::genParticles 
                      (  events                              ,   // source  
                         std::back_inserter ( gps )   ,   // target 
                         GFROMTREE ( bquark )       ) ; // predicate          
%ENDSYNTAX%

---+++ ==GHADRON==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_hadron.html][LoKi::GenParticles::IsHadron()]]=
 
Simple predicate which returns =true= for hdrons
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all charged hadrons
GRange good = gselect ( "good" ,  GHADRON && GCHARGED )  ;
%ENDSYNTAX%


---+++ ==GID==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_identifier.html][LoKi::GenParticles::Identifier()]]=
The simple function  which returns the value of PDG-identifier of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle* p = ... ;
const double absid = GID( p ) ;
%ENDSYNTAX%
The special equality/non-equality [[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/_gen_p_i_d_operators_8h.html][operators]]
against  =std::string= and =LHCb::ParticleID= objects are defined:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GRange kaons = gselect ( "kaons" , "K+" == GID ) ; 
GRange nonmuons = gselect ( "!mu" , LHCb::ParticleID( 13 ) != GID ) ;
%ENDSYNTAX%
See also [[#LoKiCutsGABSID][GABSID]].

---+++ ==GINTREE==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_in_tree.html][LoKi::GenParticles::InTree()]]=

Simple predicate which checks the presence of the particle, which satisfies the criteris in the decay tree
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
/// select semileptonic decays of beauty baryons: 
GRange good = gselect ( "good" , GBEAUTY && GBARYON && GINTREE( GLEPTON ) ) ;
%ENDSYNTAX%

---+++ ==GLEPTON==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_lepton.html][LoKi::GenParticles::IsLepton()]]=
 
Simple predicate which returns =true= for leptons
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all neutral leptons
GRange neutrinos = gselect ( "neutrinos" ,  GLEPTON && GNEUTRAL )  ;
%ENDSYNTAX%

---+++ ==GM==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_mass.html][LoKi::GenParticles::Mass()]]=
 
The function which returns the mass of the particle: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const HepMC::GenParticle* p = ... ;
const double mass = GM (  p ) ;
%ENDSYNTAX%


---+++ ==GMAX==, C++ type =[[http://lhcb-release-area.web.cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_max.html][LoKi::Max&lt;const HepMC::GenParticle*&gt;]]=
The function which evaluated the maximum from the several other functions:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GRange inCaloAcc = gselect ( "inCaloAcc" , GMAX( abs(PX/PZ) , abs(PY,PZ) ) < 300 * mrad ) ;
/// the same:
GRange inCaloAcc = gselect ( "inCaloAcc" , max( abs(PX/PZ) , abs(PY,PZ) ) < 300 * mrad ) ; 
%ENDSYNTAX%


---+++ ==GMESON==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_meson.html][LoKi::GenParticles::IsMeson()]]=
 
Simple predicate which returns =true= for mesons
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all charmed mesons:
GRange good = gselect ( "good" ,  GMESON && GCHARM )  ;
%ENDSYNTAX%


---+++ ==GMIN==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_min.html][LoKi::Min&lt;const HepMC::GenParticle*&gt;]]=
The function which evaluated the minimum from the several other functions:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GRange inCaloAcc = gselect ( "inCaloAcc" , GMIN( abs(PX/PZ) , abs(PY,PZ) ) > 30 * mrad ) ;
/// the same: 
GRange inCaloAcc = gselect ( "inCaloAcc" , min( abs(PX/PZ) , abs(PY,PZ) ) > 30 * mrad ) ; 
%ENDSYNTAX%

---+++ ==GMOMDIST==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_momentum_distance.html][LoKi::GenParticles::MomentumDistance]]=

The function which evaluates the euclidian distance between particle's 4-momentum and some reference 4-momentum.
It is very useful for kinematical matching.

---+++ ==GNEUTRAL==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_neutral.html][LoKi::GenParticles::IsNeutral()]]=
 
Simple predicate which checks the charge of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all neutral leptons
GRange neutrinos = gselect ( "neutrinos" ,  GLEPTON && GNEUTRAL )  ;
%ENDSYNTAX%


---+++ ==GNINTREE==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_n_in_tree.html][LoKi::GenParticles::NInTree]]=

The function which counts number of particles in th decay tree of the particle, which satisfy certain criteria:
 %SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// get Generator information
const LHCb::HepMCEvents* events = get<LHCb::HepMCEvents>( LHCb::HepMCEventLocation::Default ) ;
typedef std::vector<const HepMC::GenParticle*> GenParticles ;
/// select b(and antib) quarks from decay of higgs, 
/// == "count of Higgs occurances within parents " 
GenParticles bquarks ;
LoKi::Extract::genParticles
   ( events                         , 
     std::back_inserter( bquarks )  , 
     ( "b" == GABSID ) && 
        1 == GNINTREE( "H_10" == GABSID , HepMC::parents ) ) ;
%ENDSYNTAX%

---+++ ==GNLT==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_nominal_life_time.html][LoKi::GenParticles::NominalLifeTime()]]=
 
The function which return the nominal life time of the particle, 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select long-lived particles
GRange inAcc = gselect ( "inAcc" ,  GNLT > 1 * mm )  ;
%ENDSYNTAX%


#LoKiCutsGNONE
---+++ ==GNONE==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/struct_lo_ki_1_1_boolean_constant.html][LoKi::BooleanConstant&lt;const HepMC::GenParticle*&gt;(false)]]=
The most trivial _"select-nothing"_ predicate which always returns ==false==

---+++ ==GNUCLEUS==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_is_nucleus.html][LoKi::GenParticles::IsNucleus()]]=
 
Simple predicate which returns =true= for nuclea
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all nuclea
GRange nuclea = gselect ( "nuclea" ,  GNUCLEUS )  ;
%ENDSYNTAX%


---+++ ==GONE==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/struct_lo_ki_1_1_constant.html][LoKi::Constant&lt;const HepMC::GenParticle*&gt;(1)]]=
The most trivial _"select-nothing"_ predicate which always returns ==1==

---+++ ==GQUARK==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_has_quark.html][LoKi::GenParticles::HasQuark]]=
 
Simple predicate which checks the quark content of the particles:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all particle which simultaneously contain charm and strange quark:
GRange ds = gselect ( "ds" , GQUARK(LHCb::ParticleID::charm) && GQUARK(LHCb::ParticleID::strange) )  ;
%ENDSYNTAX%


---+++ ==GP==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_momentum.html][LoKi::GenParticles::Momentum()]]=
 
The function which return the momenum of the particle: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all fast particles only:
GRange fast  = gselect ( "fast" ,  GP > 10 * GeV  )  ;
%ENDSYNTAX%


---+++ ==GPHI==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_phi.html][LoKi::GenParticles::Phi()]]=
 
Simple function which evaluates the azimuthal angle, <latex>\phi</latex>, of the particle.

---+++ ==GPT==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_transverse_momentum.html][LoKi::GenParticles::TransverseMomentum()]]=
 
The function which returns the transverse momenum of the particle: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all fast particles only:
GRange fast  = gselect ( "fast" ,  GPT> 1 * GeV  )  ;
%ENDSYNTAX%


---+++ ==GPTDIR==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_transverse_momentum_rel.html][LoKi::GenParticles::TransverseMomentumRel]]=

The function which evaluates the transverse momentum with respect some direction, e.g. the direction of the jet:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
const Gaudi::LorentzVector& jet = ... ;
// select only leptons which large pt with respect to the jet:
GRange withLargePt = gselect ( "LargePT" , LEPTON && GPTDIR ( jet )  > 1 * GeV ) ;  
%ENDSYNTAX%

---+++ ==GPX==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_momentum_x.html][LoKi::GenParticles::MomentumX()]]=
 
The function which return x-component of particle's momentum: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all fast particles only:
GRange fast  = gselect ( "fast" ,  sqrt(GPX*GPX+GPY*GPY) >  2 * GeV  )  ;
%ENDSYNTAX%

---+++ ==GPY==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_momentum_y.html][LoKi::GenParticles::MomentumY()]]=
 
The function which return y-component of particle's momentum: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all fast particles only:
GRange fast  = gselect ( "fast" ,  sqrt(GPX*GPX+GPY*GPY) >  2 * GeV  )  ;
%ENDSYNTAX%

---+++ ==GPZ==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_momentum_z.html][LoKi::GenParticles::MomentumZ()]]=
 
The function which return z-component of particle's momentum: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select all fast particles only:
GRange inAcc = gselect ( "inAcc" ,  sqrt(GPX*GPX+GPY*GPY)/GPZ <  300 * mrad  )  ;
%ENDSYNTAX%

---+++ ==GSSWITCH==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_simple_switch.html][LoKi::SimpleSwitch&lt;const HepMC::GenParticle*&gt;]]=
The function which acts according to the rule:
__ result = condition ? constant1 : constant2__. Essentially it could be considered as some 
kind of _converter_ from _predicate_ to _function_


---+++ ==GSTATUS==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_status.html][LoKi::GenParticles::Status()]]=

The function which returns _status_ of the particle

---+++ ==GSTRANGE==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_has_quark.html][LoKi::GenParticles::HasQuark(LHCb::ParticleID::strange)]]=
 
Simple predicate which checks the presence of strange quark:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select beauty and strange baryons
GRange bs = gselect ( "bs" ,  GBARYON && GBEAUTY && GSTRANGE )  ;
%ENDSYNTAX%


---+++ ==GSWITCH==, C++ type =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_switch.html][LoKi::Switch&lt;const HepMC::GenParticle*&gt;]]=
The function which acts according to the rule:
__ result = condition ?  result1 : result2__:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GFun fun = GSWITCH ( 0 < G3Q , 1/GP , GPT ) ; 
%ENDSYNTAX%


---+++ ==GTHETA==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_theta.html][LoKi::GenParticles::Theta()]]=
 
Simple function which evaluates the polar angle, <latex>\theta</latex>, of the particle.

#LoKiCutsGTIME
---+++ ==GTIME==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_proper_life_time.html][LoKi::GenParticles::ProperLifeTime()]]=
 
The function which return the proper life time of the particle, <latex>c*\cdot\tau</latex>: 
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select long-lived particles
GRange inAcc = gselect ( "inAcc" ,  CTIME > 1 * mm )  ;
%ENDSYNTAX%


---+++ ==GTOP==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_has_quark.html][LoKi::GenParticles::HasQuark(LHCb::ParticleID::top)]]=
 
Simple predicate which checks the presence of top quark:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
// select top particles (top-quark only?)
GRange good = gselect ( "good" ,  GTOP )  ;
%ENDSYNTAX%



---+++ ==GTRUE==
It is an alias for =GALL=, see [[#LoKiCutsGALL][GALL]]

---+++ ==GVEV==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/class_lo_ki_1_1_gen_particles_1_1_valid_end_vertex.html][LoKi::GenParticles::ValidEndVertex()]]=
 
Simple predicate which evaluates the validity of the _end-vertex_ of the particle:
%SYNTAX{ syntax="cpp" numbered="1000" numstep="10" }%
GRange decayedB = gselect ( "Bdec" , "B0" == GID && GVEV ) ; 
%ENDSYNTAX%



---+++ ==GZERO==, the instance of =[[http://cern.ch/LHCb-release-area/DOC/lhcb/releases/latest/doxygen/struct_lo_ki_1_1_constant.html][LoKi::Constant&lt;const HepMC::GenParticle*&gt;(0)]]=
The most trivial _"select-nothing"_ predicate which always returns ==0==







---

-- [[Main.VanyaBelyaev][Vanya BELYAEV]] - 20 Jul 2007
Topic revision: r5 - 2013-12-15 - AlexN
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