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

Deadline for comments 26 Oct 2010; CIT comments in cdsweb: Piotr Traczyk

This is the first measurement of the J-psi cross section at 7 TeV. A preliminary result was presented at ICHEP, in the paper the statistics has been increased with respect to the conference, using the same analysis method. This improved measurement will be presented for approval during the Physics Days, next week. The paper is intended for publication in the European Physical Journal C.

[[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 Submitter roberto.tenchini@cern.ch Date of document 14 Oct 2010 Deadline for comments 26 Oct 2010 Note This is the first measurement of the J-psi cross section at 7 TeV. A preliminary result was presented at ICHEP, in the paper the statistics has been increased with respect to the conference, using the same analysis method. This improved measurement will be presented for approval during the Physics Days, next week. The paper is intended for publication in the European Physical Journal C.

http://cdsweb.cern.ch/record/1299853?ln=en

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Marat

There are some problems with the PDF: there are lines with no numbers, e.g. on pp. 3 and 5.

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

(i) physics/content/clarity

- p 3, Table 1. These numbers are so small, do they affect anything?
- p 3-4. I am not sure why we switch from pseudo-rapidity to rapidity. Maybe this is logical, I have no experience with this type of analysis.
- line 202-203. Seems strange that the correction is applied then the whole of it is taken as systematic uncertainty.
- line 222-223. Does the fine-grained binning help to determine better center of mass, or what is otherwise its advantage?
- p 11, Figure 3. Is there need for any discussion of the similarity of the pT dependence in the different rapidity ranges?
- p 15. Table 7. Why are all systematic errors symmetric?
- line 349, conclusions. 'reasonable agreement between the data and the theory curves'. It depends on what the criterium is, but I would have said that none of the theoretical curves describes the measured cross sections.

(ii) editorial

- line 3 and elsewhere in the text. "J/Psi's" should not be used for the plural since it can be confused with the possessive form. Simply J/Psis would be better.
- line 100-101. Use ~ between 'fit' and reference 27 such that it is not broken in a new line.
- p 4, Figure 1. Labels too small, especially the rapidity ranges.
- line 144. '; for' -> '. For'
- line 176-177. Repetition of the word 'also' within the sentence. Remove the first occurrence at the beginning of the sentence
- line 225. 2*s: 'bremstrahlung' -> 'Bremsstrahlung' or 'bremsstrahlung'
- line 241. remove comma after 'section'.
- p 10, Table 4, caption, 1st line. Remove comma after 'bin'
- p 10, Table 4, caption, 4th line. 'Only for' -> 'For'
- p 13, Figure 4. write the pT ranges inside the plots to make clear the difference between left and right plot. add y-labels to the plots below with the pull. add a key in the legend to explain that the points are the data.
- line 293, remove comma after 'modules'
- line 326. CEM is a model and a theory? I would have left just model and removed the word 'theory'.
- p 16, Table 8, caption, line 3. 'Only for' -> 'For'

- in some places the 'T' in pT is not roman. please do a global search of 'p_' and fix this

Artur:

Based on: http://cdsweb.cern.ch/record/1299853/files/BPH-10-002-paper-v3.pdf

Maria

I think the paper is not very well written (not for a journal publication yet); I agree with the comments from Urs here: http://cdsweb.cern.ch/record/1302280/files/psi.pdf and if there is a flaw on the systemtics and fit (as others seem to indicate) it has to be checked and corrected fast.

Yi

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