Difference: CMS-BPH-10-002-001 (4 vs. 5)

Revision 52010-10-25 - yichen

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META TOPICPARENT name="CMSPaperReviews"

Report number CMS-BPH-10-002-001 Version 1

Title: Prompt and non-prompt J-psi cross sections in pp collisions at sqrt(s) = 7 TeV

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Add your name and comments

Marat

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<		There are some problems with the PDF: there are lines with no numbers, e.g. on pp. 3 and 5.
 
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<		Page 3, between lines 99 and 100: How exactly "the dependence of the peak shapes" on muon kinematics was studied, and how big is the associated systematics ?

Lines 229-232: What was the motivation for Crystal Ball and Crystal Ball+Gaussian for the signal, was the dependence on the background parameterization studied at all ? Only a choice of a second order polynomial is mentioned for the background part. We know that the yield estimation can vary a lot in our pi0 studies. Therefore, this should be explained in more detail. As we can see in Table 3, the Fit function is a quite siginificant source of systematic error.

Section 6.1, from the beginning: the method used for separating prompt and non-prompt decays appears to be confusing. As far as I know, Chris had some questions about it, so I let him comment.

>
>		There are some problems with the PDF: there are lines with no numbers, e.g. on pp. 3 and 5.
 
Added:
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>		Page 3, between lines 99 and 100: How exactly "the dependence of the peak shapes" on muon kinematics was studied, and how big is the associated systematics ?

Lines 229-232: What was the motivation for Crystal Ball and Crystal Ball+Gaussian for the signal, was the dependence on the background parameterization studied at all ? Only a choice of a second order polynomial is mentioned for the background part. We know that the yield estimation can vary a lot in our pi0 studies. Therefore, this should be explained in more detail. As we can see in Table 3, the Fit function is a quite siginificant source of systematic error.

Section 6.1, from the beginning: the method used for separating prompt and non-prompt decays appears to be confusing. As far as I know, Chris had some questions about it, so I let him comment.

 

Dorian

Line: 48 to 36
 
Artur:
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Based on: http://cdsweb.cern.ch/record/1299853/files/BPH-10-002-paper-v3.pdf
1) l14: "historical discrepancy": please rephrase, sounds funny.
2) l51: remove rapidity coverage of muon detector: already descried on line 38
3) l56-57: while interesting piece of information, I don't see how relevant it is that there were 1.6 collisions per crossing.
4) l58: "good quality data" is not immediately clear, would suggest to replace with something like "Tracker, the Muon and the luminosity measurement detectors were fully operational".
5) l61: "without any further processing" sounds unclear as to what processing you are referring to. Add a statement about HLT passthrough.
6) line 67: remove "also".
7) l68-74: as a non-expert, it is not clear to me if the MC generators listed here have all the improvements listed on lines 15-19. It would be nice to clarify.
8) l84: define "central" and "forward" in terms of (pseudo)rapidity.
9) l91: would recommend changing "cuts are applied…" to e.g.: "To reduce backgrounds from fake muons …, muon tracks are required to pass the following requirements".
10) l92: I guess it is at least two tracks in the pixel layer, not exactly two?
11) l101: Which mass distributions were used in the fit? I imagine the inclusion of J/Psi into this fit could bias the cross-section measurement? Please clarify how the correction is made, and why/how it does not cause a bias.
12) l144-147: not clear the choice of polarization for non-prompt. Could you please clarify a bit why usage of babar measurement is directly transferable here, and how the comparison of that with EvtGen is a proper evaluation of systematic? What are the settings used in EvtGen?
13) l150, 175 and 181: What values do you assign to these uncertainties?
14) l153: You need to rephrase this sentence: different implies a comparison with something, while there is none here. Would suggest dropping the first sentence, and rephrase the second sentence a little bit.
15) l161: can you motivate the choice of 20%? Maybe a reference?
16) l185: I guess it needs to be "eff_off_track is the muon identification efficiency".
>
>
Based on: http://cdsweb.cern.ch/record/1299853/files/BPH-10-002-paper-v3.pdf
1) l14: "historical discrepancy": please rephrase, sounds funny.
2) l51: remove rapidity coverage of muon detector: already descried on line 38
3) l56-57: while interesting piece of information, I don't see how relevant it is that there were 1.6 collisions per crossing.
4) l58: "good quality data" is not immediately clear, would suggest to replace with something like "Tracker, the Muon and the luminosity measurement detectors were fully operational".
5) l61: "without any further processing" sounds unclear as to what processing you are referring to. Add a statement about HLT passthrough.
6) line 67: remove "also".
7) l68-74: as a non-expert, it is not clear to me if the MC generators listed here have all the improvements listed on lines 15-19. It would be nice to clarify.
8) l84: define "central" and "forward" in terms of (pseudo)rapidity.
9) l91: would recommend changing "cuts are applied…" to e.g.: "To reduce backgrounds from fake muons …, muon tracks are required to pass the following requirements".
10) l92: I guess it is at least two tracks in the pixel layer, not exactly two?
11) l101: Which mass distributions were used in the fit? I imagine the inclusion of J/Psi into this fit could bias the cross-section measurement? Please clarify how the correction is made, and why/how it does not cause a bias.
12) l144-147: not clear the choice of polarization for non-prompt. Could you please clarify a bit why usage of babar measurement is directly transferable here, and how the comparison of that with EvtGen is a proper evaluation of systematic? What are the settings used in EvtGen?
13) l150, 175 and 181: What values do you assign to these uncertainties?
14) l153: You need to rephrase this sentence: different implies a comparison with something, while there is none here. Would suggest dropping the first sentence, and rephrase the second sentence a little bit.
15) l161: can you motivate the choice of 20%? Maybe a reference?
16) l185: I guess it needs to be "eff_off_track is the muon identification efficiency".
17) l190: "mapped" sounds strange, you have "parameterized" the efficiency.
18) l195: "The efficiency for the "->"The efficiency of the requirement for the…"
19) l199: a bias on which distribution? Eta, Pt? If this is a feature of the method, how come it is not present in MC, allowing you to study it? Can you have derived the corrections from data?
20) l229-232: how are these systematic uncertainties used in the analysis? Do they enter the cross-section measurement? please clarify in text.
21) l330-339: can you give at least a qualitative interpretation of the differences observed in different MC models, e.g. Pythia give a significantly different prediction for the prompt J/Psi's, while for non-prompt it is not so different (at least at high Pt). What could be causing this?
 
Changed:
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<
17) l190: "mapped" sounds strange, you have "parameterized" the efficiency.
18) l195: "The efficiency for the "->"The efficiency of the requirement for the…"
19) l199: a bias on which distribution? Eta, Pt? If this is a feature of the method, how come it is not present in MC, allowing you to study it? Can you have derived the corrections from data?
20) l229-232: how are these systematic uncertainties used in the analysis? Do they enter the cross-section measurement? please clarify in text.
21) l330-339: can you give at least a qualitative interpretation of the differences observed in different MC models, e.g. Pythia give a significantly different prediction for the prompt J/Psi's, while for non-prompt it is not so different (at least at high Pt). What could be causing this?
>
>

Yi

 
Added:
>
>		Things need clarification:
  1. Line 111. Why do you choose the largest pt muon pair?
  2. Line 152. Is the "J/Psi variables" referring to MC truth information?
  3. Line 229-232. The functions to estimate the systematic on fit is very weird. I would suggest to do some toy MC....
  4. Line 245. Isn't the acceptance only down to 0.8 GeV/c at this region?
  5. Line 256, 274. They still didn't explain what the "outlier" is.
  6. Equation (7). There seems to be a typo of transverse sign
  7. Figure 4 right panel. There are a few points in the pull distribution that is not in the fit above (ex. the two points around -0.4). Maybe there is a bug somewhere.
 -- Main.smaria - 2010-10-17 \ No newline at end of file
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