Comments on LHCb-PAPER-2014-022 (Tjeerd)

Abstract:
- Replace "dimuon mass is restricted to 60 to 120 GeV/c2" by
  "dimuon mass selection is between 60 and 120 GeV/c2".
  (Two times "to".)
- Replace "The Z production cross section" by
  "The partial Z production cross section" or
  "The fiducial Z production cross section".

Line 2-5:
- Superfluous first sentence. Remove it.
- Reverse first "can ..." and second "can ..." in the second sentence.

Line 10-14:
- Replace "xA < 10-2" by "xA < 3 10-2 (Ref.[3])".
- Replace "smaller than 1.0" and "below 1.0" by "smaller than unity".
- Replace "caused by the European Muon Collaboration (EMC) effect [2]" by
  "by the EMC effect [2]".
- Remove "while the prediction of RAa is due to the Fermi motion above 1.0
  for values of close to xA=1.0 [3]". 
  (No written information is given about values close to xA=1.0 and to Fermi 
  motion in Ref.[3].)

Line 21:
- Replace "close to one" by "close to unity".
- Replace "10 GeV2" to "100 GeV2".
  (See supplementary figure). 

Line 31-33:
- The "sensitivity down to O(10-4)" to what? To xA? To the cross section?
  To the energy in TeV? Please, do specify.
- Replace "at an energy scale Q2=MZ2" by 
  "at a four-momentum square scale Q2=MZ2". 

Line 38:
- Replace "their pseudo rapidities, eta (-ln(tan(theta/2)), which" by
  "their absolute pseudo rapidities, eta =-ln(tan(theta/2), which".
  (We compare to positive values.)

Footnote:
Replace "'Forward' refers to positive rapidity values defined relative 
to the direction of the proton beam, 'backward' to the negative rapidity
values" by
"'Forward' refers to muons in the direction of the proton beam and 
'backward' refers to muons in the opposite direction".

Line 41:
Add "fiducial" to "The fiducial cross section is measured as".

Line 44:
Replace "The results are compared" by
"The resulting cross sections are compared".

Line 99-102:
This is not a clear explanation:
How can reweighing of a pp candidate (by counting is as 0.1 event for instance)
change its track multiplicity to match that of a pA candidate?
Or do you mean scaling of the track multiplicity of a pp candidate
(by multiplying the track multiplicity by 10 for instance) ?
If this only concerns the efficiency determination, then this paragraph
(after rephrasing) should move to line 135 and the corresponding
suggestion to the caption (below) is irrelevant.

Figure 2:
- The rapidity scale of the right plot should be negative.
- The vertical scale "Candidates/(0.20)" still reads 
  as "Candidates*5.0". We propose "Candidates/bin".
  Also for Fig.3.
- In the caption add ", yZlab," before "in the lab frame" and
  add ", y'Z," before "in the center-of-mass frame".
  Also add "Z" to the axis lable "y'Z".
   
Figure 3:
Add information about the "scaling" or "reweighing" of the multiplicity in
either the pp or the pPb case with reference to the text.

Line 116-117:
Remove "cone, radius and R" that refer to a circular geometric constraint, 
as in "of the tracks that differ in eta and phi with respect to the muon
by less than sqrt(Delta eta2 and Delta phi2)=0.5".

Line 123:
Add "Such a high purity is expected for the Z signal."

Line 125:
Add "fiducial" to "total fiducial efficiency".

Line 135:
Also here "track multiplicity reweighted Z candidates" is not clear.

Line 136:
Replace "as a function of the muon pseudorapidity" by
"as a function of both muon pseudorapidities".

Line 142:
Add a remark about where we loose these candidates from the fiducial
region and if this is reasonable.

Table 1:
Add a final row with total systematic uncertainties.

Line 221:
Replace "the results" by "the measured cross sections".
(We seem to have a 6.8 sigma Z signal as a result too.)

Line 223-226:
- Remove "Nevertheless" and "excellent".
  Reverse first and second part of the sentence as:
  "This first observation of Z production in proton-nucleus collisions
  demonstrate the potential ..."
  So we beat CMS and Atlas here with the Z's ???
- What differential measurements? Like figure 2? 
  Add "as a function of Z rapidity".