Allow helium3 candidates to be created
This MR adds two changes that allow helium candidates to be created for the Run3 HLT2 trigger.
- Add helium3 (and helium4/alpha) to the list of known particles in the FunctionalParticleMaker
- Take into account that helium is double charged, when creating the
LHCb::Particle
While the former change is straight forward, the latter requires:
- The possibility of
q\neq 1
to be considered, when assigning a track to be a particle/antiparticle in the FunctionalParticleMaker - To modify the state2Particle function, in order to scale the momentum and it's covariance matrix correctly when converting the track state (x,y,t_x,t_y,q/p) to a particle state. To scale the covariance matrix correctly, a modification to
JacobdP4dMom
in LHCb (LHCb!4512 (merged)) is necessary, as well.
As these are modifications to an integral part of the LHCb software and the case of q\neq1
is quite rare, I didn't go for a general implementation, but made sure the new functions are only considered if q\neq1
is the case.
Deuterons along are significantly easier to add and therefore treated separately here: !3839 (merged)
Finally, the name for helium3 in the list of known particles (He3
instead of He3[0.0]
), is related to these MRs: lhcb-conddb/DDDB!131 (merged) and LHCb!4579 (merged)
Edited by Hendrik Jage