[Jlab-pwa] Minutes PWA-JLab meeting 10/19/12

Carlos Salgado salgado at jlab.org
Mon Oct 22 12:22:56 EDT 2012

JLAB-PWA Meeting


++ Software update.
-Diane is working with CC to install a "forum" software in JLab computers.

-Mark showed instructions of how to install IAU code (later, Ryan joined by EVO and we
ask if he can provide us with a tutorial session. He graciously agreed to do it in a date to be specified later).
See also the JLab-PWA wiki to find more information on the IAU software. 

++ We started discussion on Baryon contamination (see agenda links to see examples for g12 - even at higher energies Gluex and CLAS12 will need to deal with this problem).
We discussed pros and cons of several methods that could be used to deal with the situation.

1- Kinematic cuts-i.e  t' and Lab angles (increases meson/baryon ratio in the sample - worry about introduced biases).
2- Include Baryon amplitudes in our PWA (need input from theory, but it is no well establish - and we end-up with a small meson signal in a larger baryon sample to be fitted with many waves).
3- Phenomenological representation of baryon resonances to be included in fits (BW forms coming from baryon data in the experiment) and added coherently to the PWA.
4- Modeling the baryon background by fitting "lots" of waves ("mother-of-all-fits") and then subtracting this background incoherently from the data.

All have problems, a we differed in our predilections. It was decided that a very good exercise will be to study the same reaction with all the methods and compare the stability (robustness) of the PWA results. We have not done this at g12 because of time/manpower restrictions.

We have now data from g12 to perform this exercise (ie. the neutral or charged three pions - both have been analyzed using the first method), or we can use simulations from Gleux (but we need good Baryon generators(?). 
Let me know if you would like to participate in any of those analyzes.


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