[Halld-unique] [EXTERNAL] Wednesday's report

[Sean Dobbs]

Hi Beni,

Sorry for sending this so late, but here are some additional thoughts
on your slide:

Title:  The more we talk about this, the more I think that "uniqueness
tracking" is really misleading, and we should give this a more
accurate title, and only refer to uniqueness tracking when it comes up
in context.  I think you describe the problem essentially as "event
counting", which I think is a better description of the problem, but
one could call this "Combinatorics" as well.

But in general my perspective is that this is really a counting
problem, hence inherently statistical.  If we solve it on the
individual event basis, then this is fine, but not necessary.

Slide 2: Maybe at the beginning you should say that we are starting
out trying to discuss the counting problem for cross section
measurements, will move onto Dalitz/etc. examples later on.

Slide 15:  There are a couple "What to do then?"s.  I think you should
make it a little more clear that the answers to these questions will
be outputs from our group's discussions.  But it might be good to pull
a couple example plots from your other presentation - even if we
haven't 100% decided what to do, I think having some concrete examples
helps move the discussion forward.

Honestly, I think that expanding on the plots that you have right now,
and showing the invariant mass as a function of the number of showers
in the event is really valuable for deciding what to do - this is
clearly future work, but you can, for example, show the mass
distribution with only 6 photons and with more than 6 photons.

Slide 33: It's not clear to me that your first case of over-counting
is correct.  In principle it can be true for the measured 4-vectors,
but maybe not for the kinematically fit 4-vectors.  Also, even though
this discussion puts it aside, isn't it the case that we remove by
accidental subtracting, anyway?

Slide 35:  I think this 10-20% is a pretty extreme case and we should say so...

Again, I think that these will give some good discussion, and we
should move towards working out some examples more fully.

Cheers,
Sean