Many events do not conserve baryon number, and some do not conserve charge. Attached is a screenshot of two puzzling events. The initial state is always a 1 GeV nu_mu plus C12.
The first has a final state consisting of:
C11, mu-, 2 neutrons, 3 protons
That conserves neither baryons nor charge.
In that event, there is no C11 in the final state.
There was C12 in the initial state. The muon neutrino interacted with a neutron.
and there was a remnant C11:
numu + C12 = numu + n (hit nucleon) + C11 (target remnant)
The proton produced by the primary interaction (position 5 in the event record) was propagated inside C11.
After some distance (in position 6) it reinteracted knocking-out 2 neutrons and 3 protons (positions 7-11).
Whatever was left from C11 enters the event record as "HadronicBlob" (position 12). Obviously this contained
the number of nucleons needed to conserve charge and baryon number. But we did not bother modelling exactly
what that HadronicBlob was (could have been a single Be7, or some collection of target fragments
with 4 protons and 3 neutrons overall)
The second has a final state that includes a "NucBindE" with PDGid 2000000101 -- why does that have Ist=1 ??
Because this corresponds to "energy which is present in the final state". We plan to change this and reserve a status
code of 1 only for the particles that can be tracked from Geant. However this is not completed yet, so I suggest you use
only particles with status code = 1 and PDG code < 2000000000 (not a GENIE pseudo-particle).
Also the recoil nucleus (or, better, the collection of target fragments) is not modelled:
If there was a hadron re-interaction within the recoil nucleus (knocking out nucleons, breaking-up the nucleus)
what enters the event record is a "HadronicBlob".
I suggest that you don't bother passing target remnants to Geant simulation. But if you insist doing so,
you can work out a nucleus PDG through baryon and change conservation.
-- I thought I could select particles with Ist==1 to send to my other simulation program, but that obviously is not enough -- how should I determine the final particles (plus recoil nucleus)?
Also: what are the notations off to the right? In particular, what is the 3-vector P with each final-state lepton? and how does it relate to (Px,Py,Pz) ?
it is the polarisation vector.
The other two things you can usually see at the far right of the event print-out are:
* with "M=..." we show the actual mass (GeV) of particles which are not on the mass shell (eg bound nucleons).
* with "FSI=..." we show the reinteraction mode for each hadrons that reinteracts. The definition may depend on
the actual hadron transport code that was used.
