petrchal's blog

General:
1. I think it would be good to include the discussion about LHC energy R_AA results (include data points in Fig.3); and discuss J/psi suppression and its physics implications from RHIC to the LHC energy. I would suggest to make Fig.3 with all available heavy-ion energies for J/psi RAA as function of Npart.
2. Fig.4: this is whole pT integrated J/psi RAA as a function of sNN. It is worth to see some calculation/data plot for only low pT integrated range (say < 2 GeV/c, you can decide). To understand the contribution of Primordial vs regeneration effect at low J/psi pT as a function of energy.
3. It seems to me that Fig.5 (pT dependence RAA) discussion should come earlier than that of Fig.3 (Npart dependence RAA) and also in the text.
4. Fig.5: We probably need to include LHC results to show pT dependence RAA.
5. AN Section 6.3: No sufficient and intermediate steps are mentioned about <p_T^{^2}> calculation. Please include pp baseline information for these energies and some intermediate step/plot.

Abstract: ….previous measurements at 39 and 62.4 GeV ->don't you want to mention 200 GeV here?

L37: I would suggest break this 2nd para [L25-47] into two from L37 ("Significant suppression is observed at SPS…"). Make one on J\psi production and another on J/psi suppression. In this 2nd para of Intro, we discuss again about QGP and CNM effect, etc, that we have already discussed in 1st para. It needs a bit rearrangement.
L53: "…and can quantitatively describe the experimental measurements. " -> Make a separate sentence. This is a big sentence. It reads awkward.
L94: The dataset utilized in this analysis contains around 1.3×109 minimum-bias events … -> Better to mention integrated lumi. Of MB event rather than total events
L116: by counting the number of charged tracks within |η| < 0.5 -> Mention what track conditions are used for this selection. Either they are the same track as your analysis (primary vs global)  L125: to the event vertex needs to be less … -> is this "primary vertex"? Then mention that. "Event vertex" is not meaningful.
L129: …, where -> Adjust this gap
L133: …a mean of 0 and width of 1. -> …a mean of zero and width of one.
L143: A TPC track is matched to a BEMC cluster geometrically … -> Do you mean "BEMC cluster" or "BEMC tower"? Cluster generally implies 2x2 or 3x3…
L147: …peaked around 1 -> peaked around one (another 1 in this sentence)

Table2: "Total" -> Do you mean "Cumulative sum"?

L173: pairs (open circles) -> remove "(open circles)" [not required in the text,]
Same for "(red histogram)" and other places
[Put all these in the caption]

Fig.1: need to include S/(S+B) for this plot. in the text, it needs to have a sentence.  
L215: "The raw J/ψ counts are obtained directly from the fit function instead of the de- fault bin-counting method, .." -> In analysis note Fig.11,12.., the fitting curve and data points have some fluctuations especially at high pT. Probably. It is minor effect. Any comment?

In the text and Eq.2; all places: "epsilon_{total}" -> "total" should be roman.
Similar p_{T} -> "T" should be roman. [Not consistent allover]
N_{MB} -> "MB" should be roman
Roman because they don't carry any value.

L251: dlectrons. -> dielectron
L250-258: Bullets do not need period at the end. [as they are not complete sentence]
L268: sigma_pp -> "pp" should italic [ because they represents particle]
L279: 0.2GeV/c -> needs a gap  L312: collision energies (left) -> remove (left) 
L317: "a flatter pT dependence of inclusive J/ψ RAA at low pT range is seen at √s = 200 GeV compared to lower energies" -> This reads like the flat pT at only low pT, but the Fig5 shows at 200 GeV R_AA shows no pT dependence within uncertainty.
Then the following sentence does not make sense for only low pT.
"due to larger regeneration contribution at 200 GeV and larger nuclear absorption at lower energies at low pT."  Hence we need probably LHC data points.

L329: …second moment (⟨ p2T ⟩) -> second moment of pT distribution (⟨ p2T ⟩)
L336: "2.53 ± 0.05 (GeV/c)^{^2}" -> is this a statistical, systematic or combined uncertainty?

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Comments from Petr:

General comments:
The paper is generally well written, but there are couple places where I have problem understanding what exactly was technically done.
The physics conclusions are not very strong. The abstract does not help very much in this sense.
I do not understand what “models could describe” mean.

One technical question: Should we use italics for “c” – light speed?https://desktop-publishing.web.cern.chcdtprules.htm It seems the italics is used in the text, but not in figures.

It takes very long during reading to find out that the J/psi are obtained from dielectron channel. One basically first finds the Table 1. before this is discussed.

L27: “significantly larger” sample does not tell much. Can say in in term of “orders”?
L78: “will shed” .. sounds somewhat awkward, can we say something like “help to further constrain”
L81: This where at the latest point should be said that we use dielectric channel.
L94,111: contains around – I’d remove the “around”. It is clear the number is rounded.
L107: It should be said the it is based on the coincidence of signal in VPD.
L125: “To assure high quality, accepted tracks ... the distance of closest approach to the event vertex needs to be less than 1 cm” This is confusing, I assume the 1cm cut is there to select primary tracks not high-quality ones.

-----------Figure 1----
When I print the paper on A4 the plot is confusing. The description of both panels is grouped in the top panel including the residual background and fit lines from bottom panels.
In the top panel the mixed-event unlike-sign line is basically invisible unless zoomed in online.
It is covered completely by same-event like-sign points which as I understand from text are used only for normalization, but look much more important in this figure.
This is the only place where I see an upper cut on pt 10.0 GeV in the caption. From Figure 2 and 5 the actual cut off seems to be 5GeV.
The upper cut off is not mentioned anywhere in the text. The text mentions only pt>2GeV.
Does the upper cut off actually have any effect?
Bottom panel: the dashed red clearly does not describe the shape of the residual background which results in the discrepancy
between the Crystal-Ball tail and data at ~3GeV/c^2.
Do we have a value of chi2 of the fit? There is a lot of discussion about the CB fit in the text. We should consider to put the chi2 in the plot.
---------------------------

L143: “matched geometrically” => by track projection (by projecting track...)
L176: Did you use binned or unbinned likely-hood fit?
L177: From here the text gets little confusing especially when looking at Figure 1. The text describes fit to Figure 1. I says that one component of the fit is the U-L from mixed events.
That to me suggests that the shape of the mixed background was used and the normalization was a free parameter. This is however not what is shown in Figure 1.
In Figure 1 is said that the bottom is obtained by subtraction of same and mixed events. So the figure suggest that first a subtraction was done and the fitting.
Similarly in the text it is said that the mixed-event background was normalized. Then how was it used in the fit as a second component (line 180)?
L184: First order polynomial – do you mean linear?
L191: After all the detailed discussion about fitting this line says that the yield was extracted by bin counting. This is actually confusing.
Was the fit result used to account for missing the tail of the C-B distribution when doing the bin counting?
L199 “small sample” sounds somewhat strange. If you want to say that you should stress that it was selected subsample which covers the whole period of data taking.

Small technical question regarding the matching efficiencies: Do you take probability of tack being matched to BEMC and to TOF as independent? We know that those are not independent.

To the discussion of systematic errors:
How does the binning of the histogram enter the systematic error?
Why is not the width of the Crystal-Ball free parameter in the fit? The tuning of the momentum smearing was done when Rongrong wanted to reproduce the width of the mass peak in the simulations,
but here it can (and I think should) be a free parameter.
Is there any systematic error associated with the shape of the residual background?
Since you have a tuned fit to the mass peak have you tried to get the yield from the fit integral? I would naturally expect that when reading the paper.

L233: “different track quality cuts” sounds vague suggesting there are other important track cuts that were not mentioned.
L224: The cut variations (I assume you varied nhits and DCA) should cover the systematics of track reconstruction even possibly inflating it a bit. Why do you add on additional 5%? It seems to me you are double counting here.
L227-239 Can we make some reference to papers where the procedures for cut efficiency extractions are shown in detail?
L248: Formula (2) I’d say it is more about an “extraction” of the yield then “definition”. Eq(3) The shape of assumed underlying pt distribution affects the position of the position of the marker in Figure 3, that is clear. Is there any place in the analysis during the extraction of efficiency corrections where the shape of the underlying pt distribution is used? I mean does the mentioned iterative process include also the extraction of efficiencies for the individual pt bins? L251:dlectrons → dielectrons
L252,256: interested → given(considered)
L278: uncertainties → global uncertainties (I assume)
L282: Given the errors can we really claim that we see that the suppression increases? I’d say we see significant suppression, but I’m no sure if we can claim centrality dependence.
L285 Here we claim consistency with 64GeV data. How far away are we from 62.4GeV data? I would assume this depends on how much are the errors correlated.
Can the difference to 62.4GeV be due to the inclusion of the coherent production?
Both together the claim of centrality dependence and consistency with 62.4GeV may seem as somewhat biased look a the data.
L308 Do we want to comment on comparison of models with data of other experiments? This sentence sounds to me as if it was diminishing importance of our results.

Figure 5. Is it possible to get the pt dependence from TAMU. Would we expect the two models to differ? In Figure 2 the overall suppression is the same, but the ratio of the two effects is different.
Do we expect this to project into some pt dependence?
Figure 5b. Here I would claim that the model does not fully reproduce the centrality dependence. There seems to be larger suppression in the data for peripheral collisions.
If we wanted to claim that this is due to the global uncertainties that would mean that all data point musts be shifted and at that point the central data would not agree.
So I’d say that the model shows much stronger centrality dependence then the data.
Now I’m actually little confused since difference between model and data should also be visible after pt-integration (basically taking the lowest pt bin) in Figure 3, but there the difference seems to be much smaller. What do I miss?

Figure 6 In the text we speculate about the origin of the shape. Are there any model prediction that we could compare to? It seems little unfair to skip the previously shown data from 39 and 62.4 GeV in this plot. I assume we do not have the values. Do we?
L334: We claim no significant centrality dependence. This does not seem consistent with
L282. L350 report →report on.

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Minutes of the first GPC meeting ( 8.2.2024)

This is a summary of the main points that were discussed during the meeting.

Based on Nihars comments it was discussed whether we should include result from LHC.
It was argued that this would repeat the energy dependence discussion from previous paper.
However, it could be tried how it would look like. Also, wast the <pt^2> calculation should be explained better.

The residual background extraction should be mentioned as a motivation for the M_inv peak fitting to make that section bit clearer.
There was a discussion if the background shape parameterization was included in the systematic errors.

It was discuses if the single track „baseline“ systematic error could be decreased from 5 to 2%.

The main discussion was about the consistency of the results and agreement with measurements at 62.4 GeV. The main points are:

There seems to be an inconsistency between figure 3 and 5 for peripheral collision. In figure 5 the data are systematical below model predictions.
The question is if this is only effect of the error bars or if even the data points are inconsistent. This needs to be understood.

There also seems to be a significant difference between 54.4GeV and 62.4GeV data. It was discussed that it is not clear how much are the systematic
errors correlated and how big is the influence of the fact that the p+p baseline is based on parameterization and not on measurement.
It was suggested to make ratio only between the two data set excluding the p+p reference. It was also discussed how much are
the systematic errors correlated between the two data sets.

Based on the difference in the contributions from primordial and regenerated J/psi it was suggested to get the pt dependence
also from the TAMU model and add to figure 5. This can potentially make the physics conclusions stronger.p { margin-bottom: 0.1in; line-height: 115%; background: transparent }

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Notes from GPC #364 for paper "Measurement of J/psi production in Au+Au collisions at 54.4 GeV with STAR experiment"