Differenze

Queste sono le differenze tra la revisione selezionata e la versione attuale della pagina.

--- cms:hin-14-008 [18/09/2015 09:04]
maselli creata
+++ cms:hin-14-008 [30/09/2015 11:42] (versione attuale)
maselli
@@ Linea 1: / Linea 1: @@
 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>"
+** Mario **
+Abstract:
+as function -> as a function
+about eta = 0 -> around eta = 0
+within errors -> within uncertainties
+line 6: at the LHC -> of LHC
+line 10: sizes -> size
+line 17: is "equilibrated system" correct? Perhaps "system at equilibrium"
+line 29: in collisions between heavy ions -> in heavy ions collisions
+line 32: to pp and pA -> to pp or pA (unless you can exclude that you can
+apply hydrodynamics to one and not the other)
+line 39: origine -> origin
+line 47: about -> around
+line 51: ... in such an analysis -> In this analysis, ...
+line 68: unless it is a common term in HI physics, we suggest to refer to
+the normalization of V_n as "normalization", and not "self-normalization"
+line 74: remove "used are"
+line 92: o the beam -> to the beam
+line 101: are based on -> make use of
+line 116: remove "for the high-multiplicity event selection" (redundant)
+Figure 1 caption: in low-multiplicity -> tracks in low-multiplicity
+line 133: displays -> shows
+lines 135-136 extensive feature -> structure
+line 142: magnitude -> normalization
+line 155: jet -> jets
+Figure 3 caption: Fit functions by Eq. 5 -> Fit results using the Eq.5
+function
+line 161 nor -> and so
+line 169 Table. -> Table
+line 176: is nonuniform; it is -> it not constant but
+line 190: averaging -> the averaging
+line 202: at a fixed pseudorapidity direction. -> in a fixed pseudorapidity
+direction:
+lines 211-212: by restricting one -> by restricting to one
+line 219: signals -> signal
+line 221: between -> among
+line 239: is same -> is the same
+line 241: without subtraction -> without the subtraction
+Figure 4 caption: for p-side -> for the p-side
+line 253: large pseudorapidity gap -> a large pseudorapidity gap
+line 256: related to decorrelation -> connected to decorrelation
+line 263: In the pPb -> In pPb
+Figure 5 and 6 captions: Error bars are statistical -> Error bars indicate
+statistical uncertainties only
+line 276: falls more -> falls more rapidly
+** Marco Monteno **
+The aim of this article is a careful study of the features of the
+long-range dihadron correlations observed in "small system",
+as the hot matter produced in pPb collisions at the LHC.
+..........
+A few comments on specific parts of the writeup:
+- Fourier coefficients of the two-particle correlations DeltaPhi distributions
+are used to infer the single-particle anisotropy parameters v2, v3 to
+quantify their dependence on eta, that can be compared to the predictions
+of hydro and CGC models.
+That is based on a factorization assumption: how much is it justified?
+- The description of the systematic uncertainties affecting the measurement
+of the Fourier coefficient V_n (lines 208-213) is clear, but the sentence is
+somehow "heavy", and it could be convenient to slightly rephrase it.
+- Another "critical point", where the non-expert reader may have some difficulties,
+is the second paragraph of the section "Results", especially when introducing the
+Fig. 5, where results are shown with/without subtraction of low-multiplicity data,
+arising some confusion (also the phrasing of caption of fig.5, with curves and symbols,
+is quite heavy and this does not help).
+- It is not well explained (L38 and L253) how a large eta gap may arise in presence
+of fluctuating initial conditions in a small system (pA), thus producing a
+decorrelation.
+How this decorrelation will manifest itself?
+However, the obtained results are interesting, the analysis methods are thorougly
+described, and overall the paper is very well written.
+Finally, we conclude our review by indicating the following typos in the text:
+ABSTRACT-LAST LINE   pseudorapity → pseudorapidity
+L9     at RHIC and the LHC →  at the RHIC and the LHC
+L39   origine → origin
+L40  decorreclation → decorrelation
+L60  approriate → appropriate
+L74-75  The "data used" are from pPb....... by the CMS detector in 2013 "are used"
+        (remove the second "are used")
+L92  o the beam → of the beam
+L127-8   The "correction factor" at L127 is then quoted as "efficiency correction"
+at L128. I would prefer the first naming.
+   Eq.4    the factor E should be replaced by \epsilon  (the rec. efficiency quoted
+at L129)
+L131   A citation is done for GEANT. No citation for PYTHIA?
+           Maybe you should ref to:  JHEP 0605 (2006) 026
+  FIG.2  !!!   Inconsistency between figure legenda and figure caption!
+               Red dots correspond to distributions of associated yields after
+               background subtraction for low-multiplicity pPb collisions
+               (according to second line of the figure caption), whereas the legenda
+               in the right-upper panel says the opposite!
+               The figure caption is wrong and must be corrected.
+L144  radian   → radians
+L153  remove the misleading formula of the differential yield, since you are quoting
+here the near-side averaged (integrated of |DeltaPhi|<pi/3) correlated yield, shown
+in fig. 3
+L224  propopagated  → propagated
+L237   Eq. 10  → Eq. 9
+  FIG.5    (end of the 4th line of the figure caption):    and →  the
+L277   why "perhaps less"?  To attenuate, rather use: "slightly less"
+L282  Two-particle Correlations → correlations
+L348   Central d+ Collisions → Central d+Au Collisions
+L353  doi:doi →  doi
+L389   (end of line):   PHYS.REV. C     I suppose is a "submitted to" . No arXiv ref?