class HParticlePair: public TLorentzVector

 checks if pair is created by sim objects

 sets fPID1,fPID2,fMotherPID and fills lorentz vectors
 opening Angle etc.

 returns the pointer to the first valid daughter
 returns 0 if no valid daughter is found

 returns true if both daughters
 have a parentTrack > 0 (mother is inside GEANT)
 both parent tracks are the same

 returns true if both daughters
 have a parentTrack = 0 (mother is outside GEANT)
 and the stem form the same source (geninfo > 0,
 geninfo and geninfo2 are equal)

 returns parent track, grand parent track, geninfo and
 geninfo2 of the daughter with index (first valid daughter if index==-1).

 sets pairflags , candidates and calls
 calcvectors. Supposed to be called at initial
 filling.

 sets pairflags , candidates and calls
 calcvectors. Supposed to be called at initial
 filling. candidate1 will be filled from
 mother + decay vertex from the pair.

 sets pairflags , candidates and calls
 calcvectors. Supposed to be called at initial
 filling. candidate1 and candidate2 will be filled from
 mother + decay vertex from the pair.

 print pairs flags

 print option bits
 bit   1 : print particle infos                      (selection == 1)
       2 : print pids, oAngle and polarities         (selection == 2)
       3 : print hit indices and META selection info (selection == 4)
       4 : print vertex infos                        (selection == 8)
       4 : print pair flags                          (selection == 16)
 default : print all

 clears all data elements but not vectors!