[Frost] poster and talk for Gordon

[Franz Klein]

Dave,
your argument is taken!
Natalie's results are not fully consistent with GRAAL nor g8b. Both use the cross section contributions from beam-recoil components, fitted together with Ox and Oz. Natalie's T asymmetry relies on proper separation of contributions of other asymmetries, in particular F, but also (to a certain extent) Cx, Cz, Tx, Tz, Ox, Oz, P, Sigma, G, which all contribute as double or triple polarization components in the cross section. When I write "to a certain extent" I mean that the decay proton was detected to identify the reaction. To which extent this changes the extraction of F and T, is something that has to be studied using MC data. I don't think that contributions of triple asymmetries are visible in the observable T after contributions of F (and with it any beam helicity components in the equation) were factored out (like done in the moment method, see Natalie's talk slide 6). Of course, there is still the question whether other moments, which are not related to physics (modulation of the cross section due to spin orientations), have any measurable entries. This would reflect poor knowledge of CLAS acceptance.  

During the presentation of the g8b analysis on the last collaboration meeting I asked about Stefi's studies to evaluate the proper contributions of these observables to the fit (sorry, I figured out later that my question was actually insignificant since the current g8b analysis still uses a somewhat questionable max.Likelihood fit instead of Stefi's Likelihood functions).
Another topic that was not addressed in the presentation was that of reproducibility of the fit results using known input asymmetries (i.e. simulated data using specific values of Sigma, P, Ox, Oz - and/or using your extracted values). I assume the Glasgow group is working on that.

Cheers,
Franz


----- Original Message -----
From: "Dave Ireland" <David.Ireland at glasgow.ac.uk>
To: natalie at jlab.org, frost at jlab.org
Sent: Monday, August 4, 2014 12:04:29 PM
Subject: Re: [Frost] poster and talk for Gordon

Hi Natalie,

Nice slides and poster, but I am a little concerned with values you are 
still getting for Target asymmetry. Your results for T are not 
consistent with GRAAL, but they are also not consistent with g8!

The formula you cite in slide 6, is valid only if there is no recoil 
information. If you use any of the decay products of the Lambda (pion or 
proton) to identify your events, you cannot help but be sensitive to 
recoil polarization and anything that depends on it. With circular beam 
polarization, transverse target polarization and recoil information, you 
are sensitive to 11 observables! You need to fit for all of them 
consistently.

Even if you pick out the cosine moment, there are other terms in the 
product which we know to be sizeable. For example Ox is large in the 
region you cover. That could be the origin of the discrepancies you observe.

Cheers,

Dave




On 08/04/14 13:15, natalie at jlab.org wrote:
> Hi,
> I will be attending the pre-Gordon conference and give a short talk and
> then show a poster at the Gordon conference. Please find them at these
> links:
>
> http://www.jlab.org/Hall-B/secure/g9/natalie/gordposter2014.pdf
>
> http://www.jlab.org/Hall-B/secure/g9/natalie/frontiers.pdf
>
> If you have any concerns or suggestions, please let me know.
>
> Thanks,
> Natalie
>
> _______________________________________________
> Frost mailing list
> Frost at jlab.org
> https://mailman.jlab.org/mailman/listinfo/frost
>

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-- 
===============================================================
                  Franz J. Klein, Associate Professor 
                  CUA, Department of Physics
                  Washington, DC 20064
  office: Hannan Hall 206          phone: 202-319-6190 
  or: Jefferson Lab,CC F-243       phone: 757-269-6672 
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