Comments from the JINR group

Comments to the STAR paper "Femtoscopy in p+p collisions at RHIC"
(Jan Fedorisin, Peter Filip, Richard Lednicky and Stanislav Vokal for JINR)


Abstract:  What about to put "200 GeV" in one line?

109: "The extraordinary flexibility of the machine"
     Since e+A and p+A collisions are not yet possible,
     it can better be reformulated as:
      "High flexibility of the machine"

139: measuresments -> measurements

144,398: "HBT radii" -> femtoscopic radii

144: the mass -> the transverse mass

146: [13] -> [13,10]

162: HBT correlations -> Femtoscopic Bose-Einstein correlations

165-166: "less clear and well developed" perhaps should read
         "less clear and not well developed"

181-183: into the context both of ... and
         (as much as possible) into the context of previous ->
         into the context both of ... and
         (as much as possible) previous

224-225: Pratt-Berttsch "out-side-long"
         coordinate system [23,24]      ->
         "out-side-long" coordinate
         system [gra'77,pod'83, 23,24]

add earlier references:
gra'77: P. Grassberger, Nucl. Phys. B 120, 231 (1977).
pod'83: M.I. Podgoretsky, Sov. J. Nucl. Phys. 37, 272 (1983).
(particularly, see eqs. 12,13 in [pod'83])

283: separation distribution.           ->
     separation distribution [led'79].

add pioneering reference on the topic:
led'79: R. Lednicky and MI. Podgoretsky,
        Sov. J. Nucl. Phys. 30, 432 (1979)

301: vanishes.          ->
     vanishes [cso'91].

add pioneering reference on LCMS:
cso'91: T. Csorgo and S. Pratt,
        Proc. Workshop on Heavy Ion Physics,
        KFKI-1991-28/A, p.75.

314: points. ->
     points and over the angles of the relative
     three-momentum \vec{q} in the pair rest frame.

380: C_F(q). ->
     C_F(q), especially taking into account their
     rather small values of the radii in p-p collisions.

395: breifly -> briefly

431: their the -> their

481: ...[0.00,0.12] GeV/c.
     Why such a range? No comment in text.

492: to present -> of present

509: ... Black dotted and purple dashed curves ...
and
511: ... Red curves
     Colors are OK in the online text,
     but how it will be seen in the paper copy?

574: R_{inv},extracted -> R_{inv}, extracted

566-591: Perhaps it should be explicitly mentioned why
         dNch/deta=7 is chosen to select the events in
         low and high multiplicity classes

652: STAR's -> of STAR's

651-657: this paragraph requires an improvement,
         description of figures 11 and 12 is not very clear.

680: Nch -> N_{ch}

There is a huge amount of "HBT" garbage which, in most cases,
can be removed or substituted:

199,246,396,531,550,611,
689,701,710,760,774,787 :  HBT -> femtoscopic

247,551,567,574,602,613,
614,629,636,667,675,716,
719,732,740,748,766 and
caption of fig.9        :      remove "HBT"

675-676: lower HBT radius, at a given multiplicity ->
         lower radius obtained by E735 at a given multiplicity

694-700: Please explain why <mt> and Sqrt(2/3)|p| variables
         can be used on the same horizontal axis to compare
         Tevatron  and STAR data.

706: lonngitudinal -> longitudinal

727: "Additionally Alexander's explanation ..."
     sounds too personal. Please replace by
     "Additionally, the arguments from [64,65] ..."

736: HBT -> Bose-Einstein enhancement

750: resonannce -> resonance

759-764:   The sentence starting with "With a very similar ...."
           is significantly emotionally NEGATIVE.
           The same content can be expressed by a more
           appropriate and more neutral statement:
           "With a very similar model, Humanic [71] was able to
           reproduce femtoscopic radii measured at the Tevatron [34]
           only with strong additional hadronic rescattering effects."

832: remove "Russian Ministry of Sci. and Tech." (no more exists)


Comments to figures:

Fig.1: Offset of horizontal axis title should be enlarged.
       It touches label 0.3.

       Perhaps add links to Eqs. used for the
       fits directly on the figure:
       measured CF
       standard fit (11) \Omega=1
       \delta-q fit (13)
       \xi-\beta fit (14)
       EMCIC fit (15)

Figs.1-5: Fonts in X/Y- descriptions should be larger
          and unique;
          offset of horizontal axis titles should be enlarged

Fig.7: Offset of vertical axis title should be enlarged
       (it touches label 1.5).

Fig.9: Zeros on vertical axes of the upper plots
       overlap with 8's of the lower plots.

Fig.10: Y-descriptions should be larger (as on Fig.9.)

Fig.12: on the left vertical axis (upper half)(lower half)
        substitute R_G by R_B/2
        and on the left vertical axis (lower half)
        add  R_G [fm]

        on the right vertical axis remove R_G=R_B/2 and R_G
        and move up the descriptions of the points

General suggestions to figures:

1) increase little bit labels offsets for vertical axes
in almost all the figures, especially small ones. Seems the labels
touch the axes in some cases, when small zoom is used. This concerns
also label offsets on horizontal axes in Figures 2,3,4,5.

2) use italic font for writing math symbols on the plots;

3) If it is possible, improve the organization of the sections
(mainly IV) containing figures and tables could be improved.
Sometime figures are placed too far (even two pages) from the
text where they are referred to.
What about to put together Figures 2,3,4,5 as well as
Tables I,II,III,IV and V,VI,VII?  Firstly, they are related and,
secondly, it would make comparison among them easier.


Some questions:

1) There is not much information in the paper describing the
fitting procedures.

2) It is mentioned at the end of section III that the
systematic errors consist about 10% (for STAR data).
10% of what (in femtoscopic radii ?) ?

3) Were some systematic errors included in fitting process or
only statistical errors were used?

4) Which fitting method was utilized? Chi-square, maximum
likelihood, or something else?

5) If chi-square method was used, what are chi-square values
of the fits?

6) The number of parameters varies significantly mainly in
non-femtoscopic parts of fitted functions as described in
section II, subsection C. It would be interesting to see and
compare the quality of the fits (chi^2/ndf) and see
covariances (correlations) of the fitted parameters.

7) Are the non-femtoscopic effects taken into account
when obtaining values shown in Table IX?

8) Why the centrality classes 0-5% and 50-80% are chosen for
the data presented in Figure 10?