[Clas_cascades] comments on phi-- paper

[Elton Smith]

Hi Hovanes,

Overall, I think the paper is in very good shape after your 
modifications. In going over the paper, I realized that we should 
specify the assumed branching ratio for the Phi-- to Xi-pi-, which is 
0.5. But this is only true above Sigma-K- threshold, or 1.68 GeV. Below 
this, we should probably use 1, which increases our sensitivity by a 
factor of 2 below this mass. It actually would make a large difference 
in both Fig 10 and numbers in our results. Should we include this change 
in branching fractions?


Here are my additional comments:

1. page 1
Should Mark be on the primary authorship?

2. title and abstract:
...process off THE deuterON...

pg 2 left column middle paragraph
"...The energy AND INTERACTION TIME of the initial photon..."

pg 2 right column top paragraph, remove phrase about trigger.
"...CLAS components. The experimental data...to properly take RATE 
effects into account.

pg 2 right column second paragraph, add dashes, remove "in"
"...on a 40-cm long and 4-cm diameter liquid-deuterium..."

pg 6 right, second paragraph, remove plural, sections -> section
...The cross section of this process...

pg 7 upper limits, add second paragraph
I may have missed it, but I do not believe we quote any of the branching 
rations that we use in extracting the cross sections. We should give 
them explicitly, especially the br(Phi-- -> Xi- pi-), where we assume 
0.5. But we should also specify what we use for the Lambda->ppi, 
Xi->Lambda pi as well. These, of course are well known and we can 
reference the PDG. However, they should be give explicitly in paper. I 
suggest a new 2nd paragraph to the upper limit section with these values 
included.

Suggestion: To extract the cross sections from events in the signal 
range, it is necessary to take into account for the branching fractions 
to specific final states. We take the braching fraction of 
$Lambda\rightarrow p \pi^-$ to be 63.9$\pm$0.5\% [pdg], the branching 
fraction for $\Xi\rightarrow Lamba \pi^-$ to be 89.89$\pm$0.04\%  [pdg]. 
The unknown branching fraction for $\Phi^{--} \rightarrow \Xi^- \pi^-$ 
is assumed to be 50\%, which is expected from isospin symmetry above 
$\Sigma^- K^-$ threshold. Below this mass we assume the branching 
fraction is 1???

pg 7 upper limits, currently second paragraph, suggest rewording. Here 
it was easier to modify existing latex text:

mv sentence up:
In this  method the systematic uncertainty is properly taken into 
account when constructing the confidence belts.
We also performed a cross check of our method with an  approach for 
estimating the upper limits BY SMITH
\cite{Smith:2008fu} based on the construction prescription by the 
Feldman-Cousins method \cite{Feldman:1997qc}.

remove sentence:
We compared our method for determining
the upper limits for acceptance corrected events to  the method by Smith.

pg 8, appendix
use "acceptance" instead of "acceptance/efficiency" (two instances). 
Earlier in the paper it was clarified that this includes efficiency and 
I don't think the "/" is correct English.

reference to Fig 11. Should this be a ref to Fig 7?

pg 9 left column, second paragraph, first sentence:
remove "often"

second sentence, remove "Then one needs". Start the sentence with "To 
find...

third sentence: eliminare can: "Then one determineS the values..."

next-to-last sentence:
"log-likelihood L WITH A MINIMUM around..."


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