Re: Fwd: Kfit with timing

[Eugene Chudakov <gen@jlab.org>]

Hall D PID Mail List:

Matt,

I am going to include a slide on the kinem. fitting with the something
like:
- 3-C fit improves the track resolutions
- kin. fitting allows a considerable improvement in identification of
  events with kaons over simple kin. constraints.
- the results depend on prominance of backrounds which are flat
  or non-Gaussian in the residual space.
- in the ideal case a strong possible suppression can been obtained
- the work is in progress

You may send me a few statements (items) you would like to make.
Also, you may include a plot. Will you do it?

Yesterday, I tried the 3-C fit, using the event 3-momentum. It gave me some additional
BG reduction, a factor of 2 perhaps, with simple cuts and without
a signal suppression. I will look further into it.

BTW, what improvement in track momentum resolution did you obtain with the
3-momentum fit? For p2K3pi events I get on average 2.4%-->2.0% - not that much.
I assumed the diagonal covariance matrix for p,theta,phi.
The energy residual becomes very narrow for "true" events,
so adding the 4-th fit should not change the track resolution.


------------------------------------------------------
Eugene Chudakov
http://www.jlab.org/~gen
phone (757) 269 6959  fax (757) 269 5703
Thomas Jefferson National Accelerator Facility
12000 Jefferson Ave, Newport News, VA 23606 USA