From dmacqueen@physics.utoronto.ca Mon Apr 23 10:30:33 2001 Date: Mon, 09 Apr 2001 16:51:38 -0400 From: Dan MacQueen To: George Velev , Henry Frisch , John Yoh , Ray Culbertson , Bob Blair Cc: cdf_people@physics.utoronto.ca Subject: CDF Toronto comments on CDF/PUB/EXOTIC/PUBLIC/5450 Dear Authors and Godparents, The University of Toronto group has read the second draft of the "Searches for New Physics in Events with a Photon and b-quark jet at CDF." We have prepared a list of general and specific comments on your paper. Again, we're sorry for the delay in getting these comments to you. We hope you find these useful. Thanks again for your paper. Dan MacQueen, for CDF Toronto. ========================================================================= General Comments: This paper improves on the first draft, although we still have a few comments and questions. The idea of model-independent limits is better motivated in this version than it was before. However, we would like to reiterate the general comments on the appendix that we made after reading your first draft. ========================================================================= Specific Comments: Abstract: 1) We suggest "charged leptons" rather than "leptons (e, mu, and tau)" 1: 1) First paragraph: Are there one or two references which could be added here which discuss new physics in general at CDF? We don't think that it would be a good idea to add references for each possible type of new physics (as that would require another page of references at the end), but one or two references at the end of the paragraph might be useful. 2) p2: In the introduction, missing Et is written in roman type, although it is in italics for the rest of the paper. 3) We suggest "leptons (e, mu, and tau)" rather than the more generic "leptons" or "charged leptons" here, in order to make clear that all three flavours of charged leptons are searched for. 4) "(massive) third generation quark": the parentheses are redundant. 5) Eqn. 1 should have a period on the end, as it ends a sentence. 2.1: 1) Paragraph 2: We suggest you delete this paragraph -- the only important information, the definition of Et, could be put in reference [8]. 2.2: 1) Paragraph 1: The first sentence is worded ambiguously. It does not make it clear that there are two separate triggers used, and events must satisfy one of two possible trigger criteria. 2) Paragraph 3: "A primary vertex ... is" -> "Primary vertices ... are". Since almost all events had multiple interactions, by the end of run Ib it would be better to re-phrase this to explain how generic primary vertices are reconstructed, without implying that there is only one per event 2.4: 1) Paragraph 1: You say "the photon cluster can have tracks accidentally associated with it and could possibly be tagged; we remove those events." Isn't this a repetition of what the second paragraph in section 2.3 says? 9 lines from bottom: It is not clear how a photon cluster can be accidentally "b tagged" when a photon cluster is allowed to have, at most, one track with p_t less than 1 GeV and two displaced tracks are required for a b tag. 2.5: 1) First and second paragraphs: "(many) parameters", "is (arguably) not", and "(two-dimensional) vector" have redundant parentheses. 2) First paragraph: "is serving as a sieve of" would be clearer as "serves to search." 3) Paragraphs 5 and 6 could be combined. The first one refers to additional jets and additional b-tags. The second one only to additional photons. Couldn't all these additional objects be described in a single paragraph? 4) In table 1, Et is used when $E_{t}$ should be. As well, $P_{t}$ should be $p_{t}$. 3.1: 1) p7, End of 2nd paragraph: You give some sense of the short-comings of the CES method. Why not include a similar benchmark for the CPR method? 3.2: 1) The title of Sec. 2.4 is "B-quark tagging". There could be other kinds of tagging (we have B-flavour tagging in the CP/mixing world). It seems a bit too much jargon to assume that all tagging, from here on in the paper, is going to be b-quark tagging. Couldn't you include "b" to qualify tagging in the title of this section and where you use it subsequently? We recognise that this will mean there are alot more "b"s included in the text, but we think they are important for clarity. 3.3: 1) The sentences that starts "Readers familiar with CDF..." are too colloquial. It will discourage readers who are not familiar with CDF from reading further or trying to understand. This could easily be phrased more neutrally. 2) p8, line 4: We were not able to reproduce the "simple" argument that a charge 1/3 quark radiates more (or less) frequently than the average jet. Clearly charge 2/3 quarks will radiate more. But many jets come from gluons that don't radiate at all. So the average probability to radiate a photon must come out not that far away from a charge 1/3 quark. At the very least this argument doesn't seem "simple" to us and so perhaps we could avoid characterising it that way. 3.5: 1)Sec 3.5, last lines: We are not sure what "... the result is not statistically useful for..." means. Does this mean we can't make a 3 sigma determination? A 5 sigma determination? We are about to ask the reader to take our quantitative limits seriously -- and compare their models to them. Please try to be more quantitative here. 3.6: 1) p9, 2nd paragraph, line 2: Can you avoid using "prediction" twice in 6 words? 2) p12,13 Figs 1/2: It is not clear to us why you multiply the SUSY predictions by a factor of 4 (40 in one case, 3 later in the paper). Is this because the MC prediction is wrong by this factor or just so you can see the SUSY shapes on the plots? If it is the latter then a factor of 4 is not enough in 1a and 1c... 4.2: 1) p15: 3rd paragraph: "The list of backgrounds in Section 3.1..." -> wrong section. You mean Section 3. 2)"multiply backgrounds estimates and fractions" -> "multiply background estimates by fractions". 3) p16: 2nd paragraph: the presentations of the systematics is unclear. Better say "50 %of the real photon fraction...". Where do you justify these 50%/100% numbers? 4) Last paragraph: the use of 2.7 sigma is confusing and redundant with the 2.7 sigma referred to in the next paragraph (with a different probability). We suggest to leave it out. Also, in the counting experiment, what does sigma stand for? 5) p17: We suggest that you leave out the last paragraph, which brings out more confusion than anything else. 6) Figure 3: The body of the figure is too crowded. We suggest that you leave out the minimum and maximum probability (besides, the maximum probability isn't quoted anywhere). 7) Figure 4: This figure is not referred to anywhere. 4.3: 1) p21: Using negative number of events as predictions can be very confusing, especially when looking at figure 6: it seems that there is an excess for the 3 jets events in figure 6 b). Maybe you should start the axis at -10, if you keep negative numbers in table 8. 2) 1st paragraph: "...photon background, When" -> "...photon background. When" 3) 3rd paragraph: "E_t > 30 GeV.^{2}" -> "E_t > 30 GeV^{2} ." 5.1: 1) When reporting the limits on this specific model, your choices of parameters (such as tan beta = 1.2 and stop mass = lightest neutralino mass + 5 GeV) might seem less arbitrary if you explained in more detail why those values were chosen and how sensitive your results are to your particular choices. 5.2: 1) Since 5.2, 5.3, and 5.4 discuss the model introduced in 5.1, they might be better numbered as 5.1.1, 5.1.2, and 5.1.3. Thus, 5.5 and 5.6 would become 5.2 and 5.3. 5.6: 1) 5th paragraph: "The first point is overly efficient..." This is a confusing sentence -- does is refer to table 14? If so, it should probably say "first entry" instead. Also, it is not clear what "overly efficient" means. 6.1: 1) (85 +/- 3.4) pb^-1 should be (85 +/- 3) pb^-1. Appendix: 1) This section needs to be reread carefully to ensure its readability. 2) Your 6-point list of advantages to the model-independent approach might read better as a paragraph. 3) Point 2 might read better as "No a priori judgement is necessary to determine what is an interesting model." 4) Second last paragraph: This sentence reads awkwardly, and is not neutrally phrased (see our earlier comment on the phrase "Readers familiar with CDF.) We would suggest "In this appendix, we present three methods to calculate A\epsilon. The model-independent limits presented in this paper set limits on the model and parameter of choice." References: 1) When reading your previous draft, we complained that in some references to multiple papers with the same authors, such as Ref. [1], [11] and [13], the authors' names weren't repeated. According to the APS style guide, this is acceptable. However, in references [4] and [14], you do repeat the authors. This should be done consistently. Cheers, ------------------------------------------------------ Dan MacQueen -- Ph.D. student -- University of Toronto --- (416)978-6632 -- dmacqueen@physics.utoronto.ca --- ------------------------------------------------------