[Clascomment] OPT-IN: Data analysis techniques, differential cross sections and spin density matrix elements for the reaction gamma p -> phi p

[Reinhard Schumacher]

Hello Biplab et al.,

I have read your draft paper "Data Analysis....phi p", specifically
the February 6, 2014 version.  It is very good to see this work come
to fruition.  The paper makes it clear that you have completed a long
and carefully-done analysis process.  I don't have any complaints
about the overall structure of the presentation or of the results.
There are a bunch of detailed comments that I hope you can address
before finalizing the paper.

Title:  Every experimental paper discusses "Data analysis
techniques...", and you in this paper really are not doing anything
that was not done before in the Williams papers.  You are not claiming
to have done something revolutionaryly new in this paper in that
regard. Thus, I recommend you do not include this phrase in your
title.  Just delete it.  

line 91: you mention 2 groups but then itemize 3 groups.

line 115: this might be the place to insert a reference to the
CLAS/ODU paper on the phi.  Maybe use "A related and independent
analysis of the neutral phi decay mode was recently reported by CLAS
[ref] using the same data set as discussed here.  While consistent
with our results (see Sec. XX) the present analysis uses different
methods and also dwells on the comparison of charged and neutral decay
modes of the phi."

line 204: It always bugs me when people refer to a stochastic event
rate in "Hertz,"  since this implies a clock-like regularity.  I
recommend using "~5k events/sec." 

line 219: "requireD"

line 227: since you are giving all these timing details, I would add a
sentence to read "The beam structure contained one or a few photons
within bunches separated by 2.0 ns."

line 242: as long as you are listing CLAS g11 photoproduction results,
could you please list the Moriya et al papers here as well:

@article{Moriya:2013hwg,
      author         = "Moriya, K. and others",
      title          = "{Differential Photoproduction Cross Sections of the
                        $\Sigma^0(1385)$, $\Lambda(1405)$, and $\Lambda(1520)$}",
      collaboration  = "CLAS Collaboration",
      journal        = "Phys.Rev.",
      volume         = "C88",
      pages          = "045201",
      doi            = "10.1103/PhysRevC.88.045201",
      year           = "2013",
      eprint         = "1305.6776",
      archivePrefix  = "arXiv",
      primaryClass   = "nucl-ex",
      reportNumber   = "JLAB-PHY-13-1744",
      SLACcitation   = "%%CITATION = ARXIV:1305.6776;%%",
}

@article{Moriya:2013eb,
      author         = "Moriya, K. and others",
      title          = "{Measurement of the Σπ photoproduction line shapes near
                        the Λ(1405)}",
      collaboration  = "CLAS Collaboration",
      journal        = "Phys.Rev.",
      number         = "3",
      volume         = "C87",
      pages          = "035206",
      doi            = "10.1103/PhysRevC.87.035206",
      year           = "2013",
      eprint         = "1301.5000",
      archivePrefix  = "arXiv",
      primaryClass   = "nucl-ex",
      reportNumber   = "JLAB-PHY-13-1690",
      SLACcitation   = "%%CITATION = ARXIV:1301.5000;%%",
}


page 4 table 1: Phys Rev will definitely axe all the heavy lines in
your table, both this one and the one later in the paper.  Take a look
at some typical papers to see how they do it.  It would be better for
you if you control the detailed appearance rather than them.

page 6 fig 3 caption: "boundED"

line 429+2:  I would replace "mother" with "parent"

Eq 11: This factor looks to me like it is upside down.  Don't you want
the width to increase with increasing mass?  That should make it
"m/m_0" rather than the other way up.

line 432: replace "term" with "factor".  To me, a 'term' is added or
subtracted in an expression, while a 'factor' is multiplicative.

line 509: better English: use "examining" rather than the colloquial
"looking at"

line 529: you lost me here.  Where does the phase-space suppression
come from?  I don't recall your discussing it, and I don't understand
why the effect gets bigger at higher mass.

Fig 7:  the first of very many of your figures that are totally messed
up in the version of your paper I have.  The y-axis label is partly
missing and the legend text is all fouled up.  

Fig 8: another figure with fouled up labels.  Also, I would put x-axis
numbers on the middle and right bottom panels.

line 708+2: "...sections ARE comprised..."

line 735: "The(delete SE) three spin..."

page 13, Eq 33 and Eq 35: you never define T and T_2\mu as the
measurable observables.  

page 14 Eq 38: you don't define xsi and phi until much later.  Can you
indicate them somehow on Figure 10, and/or tell the reader that the
exact definition will be given below?

line 766:  "Kloet et al HAVE shown..."

page 14, 2 lines from bottom right:  "...this is (delete THE)
followed..."

Fig 11 caption: "...the incoming photon,(remove comma and AS...)
seen..."

Fig 12, 13, 14, 15, 16, 17, and others: I would add horizontal axis
numerical labels on the three columns toward the right.

Figs 16, 17 and others:  in-panel text labels screwed up

Fig 20, 21: need "GeV" unit on E_gamma string; also, more messed up
legend on Fig 21.

Fig 22, 23, 24, 25: to my eye the symbols for the data are too big by
about a third.  If you make them smaller it will be more pleasant to
look at.  Fig 26+ look better to me.

line 1020:  you say Fig 31 shows only a slow rise of both B and C with
energy.  But this is not true!  Lots of structure is seen, and you
need to mention this here. 

page 33 Fig 30:  "...points also involve(delete S) an..."

line 1153:  I believe the Emmy Noether phrase is obsolete:  we have no
German collaborators these days.

Figs 31, 32, 33, 34: More bad labels

Ref 28: is this not published by now?

page 36, Fig 36: In a way, this could be an important figure to
*motivate* the physics discussion, not just to have this as an
addendum at the end.  With some fix-ups, this might be better placed
in the introduction, after line 172, in a paragraph that follows the
other introductory discussion and explicitly mentions the various
reference frames.

However, the figure confuses me as it stands now.  In the helicity
frame panel, it appears to show the photon spin/helicity as not
parallel to its momentum, which is incorrect.  The "Gottfried-Jackson"
label should be under the right-side panel.  Also, the "V rest frame"
panel is somehow scrambled, isn't it?  You want "V" at rest in the
middle, with the gamma and the IP coming in from opposite directions.

That all for now!
Reinhard