From: FNALD::SMTP%"robinson@cepheid.physics.utoronto.ca" 19-DEC-1997 14:06:43.26 To: TOBACK CC: Subj: Comments on 2nd Draft of eeggMET PRL Date: Fri, 19 Dec 1997 15:06:28 -0500 (EST) From: Andrew Robinson To: FRISCH@uccdfj.UCHICAGO.EDU, toback@fnald.fnal.gov, rebcdf@fnald.fnal.gov, stuart@axcdfe.fnal.gov, yagil@fnald.fnal.gov, kuhlman@fnald.fnal.gov, mdshapiro@lbl.gov cc: cdf_toronto@physics.utoronto.ca Subject: Comments on 2nd Draft of eeggMET PRL Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII TORONTO COMMENTS FOLLOW ******************************************************************** Greetings, Recently, the Toronto group has met to discuss the second draft of the Letter entitled "Searches for New Physics in Diphoton Events in ppbar collisions at \sqrt(s)=1.8 TeV". This draft is a further improvement on an already relatively strong first draft, and we appreciate the continuing hard work of the author. Our comments will thus, for the most part, be limited to following up on the most important (in our opinion) issues that were raised in comments on the first draft of the text. Cheers, Andrew ** Thanks! General Comment: ^^^^^^^^^^^^^^^^ 1. After further discussion, we decided that the most important outstanding issue in this Letter is the discussion (in paragraph 10) of the identity of the plug EM cluster. The current discussion has left a number of members of our group with many unanswered questions. Although we have (regretfully) resigned ourselves to the fact that a discussion of why the cluster does not make a reasonable photon/tau/jet candidate is not possible in a PRL, we're still not sure that this paragraph conveys the argument with maximal clarity. The last sentence, for example, "We simply do not have enough information to establish to origin of the cluster.", could be replaced with a new sentence, located after the discussion of the SVX track, describing how an electron would be too far forward for CTC reconstruction to be reliable. We appreciate that you don't want to raise more questions than you have space to answer, but we think this paragraph may raise some unanswered questions as it stands now. ** You are right. This is a really difficult paragraph. The CDF Note describing the study of the plug cluster is almost 80 pages long. I think there are plenty of unanswered questions, and as far as I can tell, they never will be answered. Only more data will tell. As for telling what we do know in a better manner, I think the paragraph is clear. The godparents argued for a long time about the concluding sentence and they decided that the right thing to do is to say we simply do not have enough information to establish to origin of the cluster. However, your point about the CTC is well taken. Unfortunately, there isn't room for such a sentence. Furthermore, there are many of detectors which could have provided more information but which didn't because the candidate didn't pass through them (assuming it came from the primary vertex). For example, it would have been much nicer if the candidate had passed through 4 layers of silicon and not 3. I'd hate to have to explain that one in the PRL. Another point you correctly bring up is that the candidate is perfectly consistent with a photon, tau or jet; it just would have to be an unusual example. A full, or even reasonable, discussion of each possibility is important and fairly involved (again as seen in the CDF Notes), and we simply can't do it justice in this paragraph. Finally, I think that any real discussion will not come until the reader has the PRD. Even then as I've mentioned previously, it will still leave many as unsatisfied as us, but it's the facts as we know them. Specifics: ^^^^^^^^^^ (We refer to line numbers in the double-spaced version of your draft -- Thanks Dave!) ** You are very welcome. Glad to be of service. Paragraph 1, line 9: We feel that, even in the absence of a discussion of how it is calculated, it is important to include an uncertainty in your statement of our integrated luminosity. We feel that this is important in all papers that make measurements of, or put limits on, a cross section. ** A reasonable request. Done. Paragraph 2, line 9: If *I* had been involved in the construction of the plug calorimeter, I think that I might take offense to having the fruits of my labour described as the "pole-piece of a magnet". So, if push comes to shove and you need five more words... ** Those words have been removed. Paragraph 2, line 12: As you know, The CPR lies only in front of CEM. Do you think specifying "CENTRAL electromagnetic calorimeters" might help? ** We have added the word "central". Paragraph 5, line 3: If you are committed to making "Approximately Flat in E_T" more quantitative in the forthcoming PRD (something we would encourage), you could reference it again here. ** Yes, we will give the efficiencies in more detail in the PRD. We really don't want to reference the PRD too many times. It's already reference 4 times in the text, and once in the references. Paragraph 6, line 2: Everyone in Toronto who read the second draft circled the phrase "improve the rejection against biases and fluctuations" as being particularly awkward. I don't know how to "reject biases", only how to correct for (some of) them. How does "minimize the effect of biases and fluctuations" sound to you? It even saves you seven characters. ** Sounds good. Done. Paragraph 10, line 1: It really is grammatically incorrect to use "Monte Carlo" as a noun in this context. We much prefer "a Monte Carlo calculation [21]" to "the SPYTHIA Monte Carlo [21]". I know that theorists do it, but CDF papers should read better than your average theory paper. ** We stayed with the usage in all the CDF Papers. We think Monte Carlo is indeed a noun. Paragraph 12, line 3 I'm not so sure that I would label N = 3, expected = 0.3 +/- 0.1 (line 5, table I) as "good agreement with Standard Model expectations". How does "no significant evidence for anomalous \gamma\gamma production" sound to you? ** You are correct that the lepton number, taken by itself and out of context would probably not be deemed good agreement. However, we have discussed these events. The dominant background, which is diboson production (as discussed in the text) predicts 0.3 events, and we observe 2 of diboson type. This is perfectly consistent. As a check (this is discussed in the CDF Notes) for photons above 25 GeV we expect 0.2 events and see 0. Again perfectly consistent. I think outside of the one event, we really do have good agreement. Because the one event is not in good agreement we have marked it as a possible exception. Reference [1c] Mohapatra's name has three a's ** Yes! That has been fixed. References [1], [16], [17], [21], and [23] should end with periods. ** Those also have been fixed. Thanks again. END OF TORONTO COMMENTS ******************************************************************** Andrew Robinson e-mail: robinson@physics.utoronto.ca