[Clas_cascades] Comments to Sigma*- analysis note

[Elton Smith]

Hi Haiyun,

I have just now had time to take a look at your analysis note. 
Generally, it is well organized and readable. Here are my comments:

General:
1. It would be nice if you could add readable legends to your 
postage-size plots. Otherwise indicate direction (left to right, top to 
bottom) and also the bin widths, e.g. 0.25 GeV energy bins in the caption
2. You should add a section in the introduction to define your 
variables. For example you use t (=(p_gamma - p_K+)^2?), but never 
define it. The same can be said for t', etc. Sometimes variables can be 
used differently in various contexts, so you should not assume that a 
particular variable is unambigious. It can also help make the text 
cleaner, if you can refer to specific variables.
3. I suggest you move Section 7.1 and 7.2 into the introduction, perhaps 
breaking 1.1 into two subsections, one on Sigma*- and one on Sigma*0. 
First, this makes sense, because the introduction discusses previous 
experiments and the theoretical context. But also, it clearly separates 
the other experiment from your data. At the moment Figs 62, 63 and 64 
could easily be assumed to be your data, unless one reads the text 
carefully.
4. Generally, the reference section is very meager. I have suggestions 
below where references are needed.

Specifics:
p. 5 middle last paragraph, after two categories:
Suggestion: One group comprises particles listed in the PDG and the 
other group includes quark-model predictions for "missing states," which 
have note yet been observed experimentally.
The PDG should have a reference to the particular paper you used. For 
example, some properties change from volume to volume, so you should 
have the specific reference.

p.6 event selection
It is good practice to have an appendix with all the precise run numbers 
you use (instead of giving instructions for how to obtain the golden 
runs. Five years from now, these might not be available. It can also be 
divided into before and after Christmas.

p, 13. My understanding is that you choose the pi-,p combination with 
the mass closest to the central Lambda mass. Does this affect your final 
answer? Can you estimate the systematic error induced by this selection?

p. 16 Tagger correction
You should reference Paul's thesis.

p. 21 Section 3.6
References to CALDB and GPP?

p. 21 Section 3.7, last sentence. You say that the 0.45 GeV cut is 
generated. Is this Monte Carlo, data or both? Is the generated 
distribution similar to the measured one? I don't quite understand why 
the cut is 0.45 and not 0.25 or higher?/

p. 22, 3.8 last sentence, clarification:
... process, we require the MM to be less than 0.4 GeV.

p. 24.
You make a cut on the K* events. I did not see any discussion on how 
this affects your final results. Is there a systematic associated with it?

p 25. 4.1
What event generator did you use? You should also write down all the 
parameters (or the critical ones) that go into the generator. Define you 
t variable
In this section you should also state that you use a t-slope of 2 GeV-2

p. 27. 4.2
Again in GPP it is useful to specify the resolution parameters used for 
tof and DC detectors.

p. 27. Trigger simulation
Did you look into the correction for Lambda's decaying outside the start 
counter? We added a correction in the pentaquark paper (I believe the 
estimate was 5%?) This was necessary in our case because we required 4 
tracks with ST hits.

p. 27, 4.4 , first line
... can be found in Ref. [1].

third line suggestion
photons, which are not necessarily selected by the trigger, to calculate...

p. 29, second line
...system, even though all T-counters are on.

p 31 4.6
Trigger efficiency correction section could use clarification.
first sentence:
...discrepancy in the observed yields of various EG3 run periods.
4th sentence
studied the pentaquark [needs reference].
last paragraph
You need to define your sample. Graphs say 4-track events. Are they the 
same sample as your Sigma*-? Is it a less restrictive sample? Are they a 
Lambda sample with two additional tracks?

On Fig 36 and 37, I don't see the "discrepancy" near the 60th run. Do 
you mean discontinuity?
I am also confused about Figures 38 and 39. Are these the projections of 
figures 36 and 37 in different units?

p. 32. Are the 1.58 and 2.56 number coming from Figs 38 (mean 2.619) and 
39 (1.657)??
The procedure needs clarification.

p. 35.
Instead of using "top left to bottom right" on these plots use "left to 
right, top to bottom". Also add bin widths (0.4 GeV?)

p. 37. 5.2 Integration over the Breit-Wigner
The integral is infinite, so you need to define the range of integration 
(in units of the full width Gamma)

37, 5.3 Side band extraction...
The discussion in this section would be helped tremendously if you take 
a single energy bin from Fig 41, 42 and 43 and replot so that all 
information can be visible. You can then use that series of plots to 
explain the procedure and give specific numbers for that bin. The 
discussion is sufficiently convoluted that without being able to read 
any information from the small plots, the discussion is difficult to follow.

3rd line second paragraph p 38
" Cut away the invariang mass peak according to the PDG": Do you mean : 
Fit do data outside the mass range of 1385 - Gamma to 1385 + Gamma? Give 
specific numbers for these (not just refer to PDG).

p. 40 5.4 last sentence
use "measured" instead of "real"

p. 45 5.7
Define t'

p. 46 t plots
It seems like the fits do not include the last data points in the first 
series of plots. Did you omit them, or does the fit just not plot that 
far? If omitted, why?

p. 47, 6.1 & 6.2
If the event sample is the same for the fiducial volume and pi momentum 
studies, the statistical errors are not independent, so comparing the 
extracted data points to the statistical uncertainties is not valid. You 
should also attempt to extract an quantitative number from the plots. 
One possibility is to take the average (over energy) deviation between 
extractions and quote that as your systematic uncertainty. But you need 
a number.

p. 52 Table
Reference -> See Section

p. 56 -58 Figs 62-64
See general comments.
Also: Instead of just citing [3] at the end of the sentence, you should 
state "Data taken from Ref. [3]" to make it clear.

p. 56 following eq 3
Next to last sentence, use variables
The angle distribution for Sz=1/2 should behave like the first term, 
alpha, and the Sz=3/2 state should behave like the second term, beta, of 
Eq. 3.
You need to add a comment about gamma. What does this represent? Is it 
an interference? [Note that you change notation to mz in the figure 
captions. You may wish to make them consistent.

p. 58, before 7.3
The "preliminary" data of Guo? I thought these data were published?? If 
not you need a better reference than "private communication"

p. 58. Results, last two sentences first paragraph
...the distribution is fitted TO EQ 3 and plotted in Fig. 64. The ratios 
beta/alpha and gamma/alpha (?) for different photon energies are shown 
in Fig. 65.

p. 59 Fig 65 caption
I believe the first sentence refers only to the red data. You should add 
a description of the blue data points.

p. 59 first sentence
Again, use variables beta/alpha, gamma/alpha to make the text cleaner.
The discussion about the Chi2 is unclear to me and the discussion should 
be amplified, with a reference to Fig 66 (currently missing).


p. 61 Summary
second line, should this be 1.5 GeV?
first line second paragraph
On the other HAND, the production....

middle second paragraph:
In case of more than one possibilities, the ratio of them is the same 
instead: I do not understand this sentence.

I suggest you add two plots combining data from 62 and 65: Plot 1: Ratio 
beta/alpha for Sigma*- and Sigma*0, Plot2: Ratio gamma/alpha for Sigma*- 
and Sigma*0. That will highlight any differences between the two 
reactions and will make it easy to discuss, compare and contrast them in 
the text.

Generally, it will help to amplify the discussion somewhat and attempt 
to draw some crisp conclusions. You will need a few sentence highlights 
for the paper abstract.

Let me know if you have any questions about these comments.  Cheers, Elton

-- 
Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite #16
Newport News, VA 23606
(757) 269-7625
(757) 269-6331 fax