Questa è una vecchia versione del documento!
http://cms.cern.ch/cds/HIN-14-008
Ernesto
Congratulations for this nice work. Overall the paper is well written. We have suggestions (Type A) which can make the understanding of the topic easier, especially for people who are not directly involved in the HI analyses. We have also two comments about the physics content (Type B).
Type B
In the Introduction there is a lot of emphasis on the potential of this analysis on discriminating about hydrodynamic vs CGC models. On the other hand along the paper the experimental results are compared only against the predictions of the hydrodynamic model. As you mention the current accuracy on the measurement does not allow to draw any conclusions. Anyway it would be nice to see on Figure 7 also the curve predicted by CGC. If the CGC prediction is what is called “inclusive pT” I would write it explicitly
I would swap the columns of Figure 3 in order to have the delta_eta=0 regions of Pb-side and p-side histograms close to each other. Is there any physical reason why the p-side yield and the Pb-side yield should be different at eta=0? If not, this means that the first term of Eq.4 should be fitted simultaneously between the p-side and the Pb-side. Have you tried to do that, thus reducing the number of fitted parameters and most likely giving a chi2/ndof closer to 1? Can you do this and include it in the study of the systematic uncertainties?
Type A
General comments about style:
- Notation: is the label “trigger” (introduced at L42) a literature standard for denoting the primary track? I have found it confusing, e.g. it seems to define a track on which the experiment is triggered. Can it be changed into “primary” or “seed” or “tag”?
- Figures: would it be possible to have the axis representing “delta_phi” in units of “pi” instead of integers?
Perhaps it is obvious for HI experts, but it not harm to mention that short/long range usually referes to the eta-separation (I have understood correctly).
L19-33: I suggest to remove this paragraph. Although it contains interesting references to previous literature, it definitively breaks the flow of the introduction, e.g. description of the models (L7-18) followed by the description of the predictions relevant to this measurement (L34-41).
L40: “decorreclation” → “decorrelation”
L42: is the label “trigger” a literature standard for denoting the primary track? I have found it a bit confusing, e.g. denoting a track on which the experiment is triggered. Can it be changed into “primary” or “seed” or “tag”?
L52: remove “dN/dDeltaEta ~ dN/deta”. At this point I have found it confusing. What it is done in the analysis is explained in detail later.
L53-54: consider to move it at the beginning of the paragraph (L42).
L70: add a one-sentence guideline about the meaning of v2 and v3, e.g. “A non-vanishing v2 indicates …”
Eq.4 “E” → in the text (L129) is “epsilon”. More in general, I would not call a correction factor “epsilon_trk” as this name rather denotes an effciency. Which is the typical size of the correction factor?
L132: I would not make “Quantifying jet contributions” a separate subsection
L133: “particle eta windows.” → “particle eta windows in low and high multiplicity events.”
L136: for my education: in which of the four panel you observe the “extensive feature on the away side”?
Figure 2: caption “Distributions” → “Example of distributions” The upper limit of the y-axis (“1”) of the lower plots is partly hidden.
L153: “1/N_trig d2N/d(delta_eta)d(delta_phi)” is the differential yield and not the near-side averaged. Either remove it or use the formula with the integral sign.
L165: “which stand” → “which stands”
Eq.8: use for the multiplication the same symbol of Eq.5 (either “\times” or “\cdot”).
Eq.9: does factorization mean that you assume no correlation? If so Eq.9 does not add anything and you should limit to write in the above sentence “v_n(eta_assoc)/v_n(0)”.
L205-207: Postpone the definition of “eta_lab” to Sec.5, e.g. around L238.
L225-226: is there any inconsistency between the value in the text (3.6%, 5.7%, 14%) and those in Table 2 (3.9%, 5.8%, 15%)? Same comment for the values quoted in the captions of Figures 4-6.
L228 “From the two-particle correlation … va Eq.7.”: already explained. Remove it?
L229, L231, L246, L247 “blue points”, “red points”, “closed points”, “open points”: I would not repeat in the text what is already written in the caption of the figure.
Figure 6: in the caption: “Bands show” → “Band shows”
L277: remove “perhaps”
L278: “vs” → “as a function of”
L280: remove “about” since the uncertainty is written explicitly “eta~1.5” → “eta=1.5” what is approximate is the size of the decrease (20%) not the value of eta where you evaluate it
Figure 7: caption: either write “average pT” or “<pT>”