More PID will be most likely needed for non-overdefined reactions
(with a missing particle). It would be nice to get some idea from Matt,
how large the additional suppression should be.
I doubt that a 1C fit can sufficiently improve the PID.
You're right that a 1C fit will definitely let in more background. As Alex has pointed out though, GlueX has been designed with excellent detection of neutrals in mind, so hopefully we rarely miss pi0's. As for the missing neutron, I would not be surprised if we do OK since it is hard to mess up pi's and nucleons and the missing neutron peak should be well separated.
The 1C fit studies are just one of a number of studies that we will need to do following the review. I would suggest a PID meeting dedicated to mapping out what studies need to be done to further investigate some of these numbers that we have come up with. It is obvious there are different camps regarding PID and we should work hard to come to some sort of convergence on how we approach this work. While it is always good to have cross checks, there's no sense in duplicate effort or bifurcating code.
A few comments about the talk:
Slide 17: I don't understand what you mean by 3C or 4C fits. There should be no point where you are performing a 3C fit on that reaction. Unless you are doing spatial vertexing?
Slide 19: Similar comment. You are making a 3C fit and cutting at 1% and then making a 4C fit and cutting a 1%? Perhaps if I heard the talk it would make sense, but the slide on it's own is very confusing.
Slide 20:
2nd main bullet - This can probably be reworded. "Additional methods of increasing..." or something like that.
3rd main bullet - If you feel it necessary to list the challenges in getting the kinematic fitter working, you should also mention that there is experience within the collaboration in overcoming these issues (Curtis, et al) and reference the successful kinematic fitter in use in CLAS analysis.