[Clascomment] OPT-IN: Hard Two-body Photodisintegration of 3He

[Reinhard Schumacher]

                                               10-17-12
Hello Yordanka et al.,

Your paper on "Hard Two-body Photodisintegration of 3He" is very
interesting. I do have a few suggestions and questions.

Line 51 Table 1
You have not cited one additional evidence for scaling in meson
photoproduction, namely the paper that Misak and I wrote on K Lambda
production.  Please expand Table 1 as follows and include the
following reference

\gamma p \to k^+ \Lambda      
s = 5-8  
angle = 84 - 120  
n predicted = -7  
n measured  = -7.1 +- 0.1

%\cite{Schumacher:2010qx}
\bibitem{Schumacher:2010qx} 
  R.~A.~Schumacher and M.~M.~Sargsian,
  %``Scaling and Resonances in Elementary K^+ Lambda Photoproduction,''
  Phys.\ Rev.\ C {\bf 83}, 025207 (2011)
  [arXiv:1012.2126 [hep-ph]].
  %%CITATION = ARXIV:1012.2126;%%



Line 177: put the word "only" after the comma and delete it from the
end of the sentence

Line 201: the paper is unclear how the events with and without
"kinematic cuts" are distinguished.  In particular the events that
form the background in Figure 2 are impressively close the the passing
events, but it is not made clear why the match should be so
marvelous.   Can you clarify for the reader how these two sets of
events were selected?

Figure 2:  it's very hard to see at first that there is a blue curve
under the red curve.  It looks almost too good to be true.  Visually,
can you better distinguish the curves, and again, can you better
explain how these curves arise from two different (buy evidently very
similar) conditions?

Line 207: the sentence that starts "Background-free..." makes no sense
to me.  There should be some context.  Since this is a small effect
(whatever it is), maybe delete the whole sentence.

Line 221: Does <10% mean +-5?  If so, I recommend using the latter
formulation.  Similarly on line 227.

Line 239: You offer no support for the assertion that "at other
kinematics" you see scaling at other angles.  First of all, what
energy are you talking about here?  Is 0.7 GeV the photon beam energy?
Also, you need at least a reference here to back up the statement. 

Figure 3: Nice result!


That's all for now,
Best Regards,
Reinhard
___________________________________________________________________
Reinhard Schumacher         Department of Physics, 5000 Forbes Ave.  
Carnegie Mellon University, Pittsburgh, PA 15213, U.S.A.         
phone: 412-268-5177         web: www-meg.phys.cmu.edu/~schumach
___________________________________________________________________