[Clas_cascades] Analysis note of Sigma (1385)

[Paul Mattione]

Hey Haiyun, I have a bunch of questions:

Section 2.2: For the tagger efficiency cuts, your bins are quite large  
compared to the size of the T- & E-counters.  Did you look at the  
#photons per counter to see if there's any additional bad counters to  
cut?  Maybe you did and I just missed it...

Section 2.4: By using a mass cut to select your photons, aren't you  
biasing your missing mass distribution by artificially increasing the  
background?  What if you had a background event that in truth  
corresponded to a different missing mass, but the other photon  
happened to give a missing mass under the missing proton peak?  Since  
the two-photon event % of some experiments that don't use a mass cut  
on the photon selection is ~10%, I wonder if you may be artificially  
increasing the statistics near your peak by a non-negligible amount.

Section 2.6: Did you guys ever get a chance to take a look to see if  
there were any trigger efficiency issues for the SC paddles in eg3?  A  
quck look at the pedestal-subtracted ADC distributions should give you  
a good idea if it's something that may be a concern.  These would be  
theta-dependent and thus may not show up well in angle-independent  
cross section scale-comparisons.

Section 5.3: The Sigma1385 fits in Figure 43 (in the sidebands of the  
spectator proton distribution) look like they were pretty difficult to  
get a handle on.  In the bins with what looks like very low signal  
(e.g. the third row) how do you know for sure what the size of the  
background is on the low-mass side of the distributions?

Chapter 6: Do you know what the systematic errors are due to the  
generated monte carlo distribution?  Differences between the generated  
MC distribution and the true cross section can cause large errors in  
the acceptance calculation in some bins due to changes in the detector  
acceptance across the width of the bins.  Also, did you try using  
different methods of extracting the yields (different background fit  
functions, background modeling, etc.) to compare?  This was a really  
large source of uncertainty for me.  Table 9.4 of my dissertation  
lists a bunch of different sources of systematic uncertainties that I  
looked at.

Other: Were you going to use kinematic fitting and/or probabilistic  
event weighting to extract the yields?

Thanks!

  - Paul


On Jul 25, 2011, at 6:00 PM, Haiyun Lu wrote:

Hi folks,

I put the analysis note at
http://clasweb.jlab.org/rungroups/eg3/wiki/index.php/AnalysisNote_Sigma1385Minus
This is for reviewing within Eg3. Any suggestions and questions are
welcome and appreciated.

Best,
Haiyun


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