[Clas_cascades] Minutes 9/9/2010

[Igor Strakovsky]

Dear Zhiwen,

I have several questions to you...

1) I am a little bit confused - what is the purpose of your analysis? In 
particular, you pretend to compare with the LEPS experiment. But your plots 
show that you have practically no statistics below 20 deg. This is especially 
so for "on Lambda(1520)", where interference amplification could be expected.

BTW, Takashi Nakano told me that he tried to change his setting so to 
reproduce CLAS conditions, and it does not work for him.

2) Then, is it possible to see your Ks recoil spectrum?  Its structure, with 
well known Sigma and Lambda states, would allow to estimare how good your 
selected pi+pi- pairs correspond to K0 decay products.

3) As far as I can see, your collinear cut is cos(theta)>0.9 while the ODU 
analysis demonstrated thar the optimal boundary is 0.98, and definitely not 
less than 0.95. Can you do such cut?

4) For the pK-Ks events you show us the spectra M(pKs). But the ODU analysis 
has demonstrated that such spectra have a bad resolution, because of proton 
measurements in CLAS. Could you show instead the spectra of MM(K-)?


Elton,

Recently, your committee accused the ODU analysis for using a t-cut. Now your 
suggestion to Zhiwen is to do just the t-cut. Have you changed your mind?

Thanks, Igor


On Thu, 2 Sep 2010 09:29:21 -0400 (EDT), Elton Smith <elton at jlab.org> wrote:

> 
> Present: Elton, Hovanes, Zhiwen, Kijun, Stepan
> On the phone: Ralf <br>
> Notes by Elton.
> 
> == Announcements==
> # Hovanes will run the next meeting, 8:00 am Sep 9
> 
> == Draft of Phi-- Paper (Hovanes) ==
> # Started including sections of the analysis note and submitted to cvs,
> but not yet ready for other input
> # There will be quite a long sections included, but they can then be cut
> back
> # Asked whether there should be discussions of two sets of cuts (liberal
> and conservative): Elton: Focus on the set of cuts used for the upper
> limit. It makes the paper simpler and easier to read.
> # Stepan: Compare results to normal cascade cross sections
> 
> == Theta+ (Zhiwen) ==
> # Started looking at g n -> K-K0p(p), with Theta+ -> K0p.
> # Advantages of eg3 are better acceptance for K- in forward direction, and
> larger overlap with LEPS kinematics compared to other CLAS analyses
> # Invariant mass plots of (K0p) shown. No indication of a peak in the
> region close to 1530-1540.
> # Stepan: list of cuts to consider are a) Missing mass peak b) photon
> energy cuts c) t-cuts.
> # Elton: Suggests to only use missing mass cut for primary mass spectrum,
> and use t-ranges as a selection only to compare to LEPS data.
> # Elton: Try to get an estimate of an upper limit to see if it is
> competitive with LEPS published results.
> 
> == Next Meeting Sep 9, 8:00 am ==
> # Phi-- Draft of paper (Hovanes)
> # Theta+ update (Zhiwen)
> # Analysis note for Lambda(1520)?
> 
> 
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton at jlab.org
> (757) 269-7625
> (757) 269-6331 fax
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Igor Strakovsky, SAID CNS The George Washington University
Tel: 703-726-8344(NV),202-994-4742(FB),Skype: igors1945_2
Fax: 202-994-3001(FB),Emails: igor at va.gwu.edu, igor at jlab.org