E852 experiment

Analysis of Eta Pi0 system with the decay Eta -> Pi+ Pi- Pi0

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Gary Adams, 4 Oct

852 folks: Vladimir has posted the latest version of the eta pi0 paper (draft 6_2) here: http://lav01.sinp.msu.ru/~vlk/E852etapiz.html Please take a look and copy your comments to the full collaboration. Vladimir (and Neal) have iterated this with the trc a couple of times but I think it is time to have a full review. This marks the beginning of a two-week review cycle. I think we have a nice result and I am hopeful that we are nearing the end. Thanks, Gary

ps. I have a couple of comments: 1)Vladimir, you did not understand my previous comment about chisq/dof. Anywhere you quote chisq/dof you also need to specify the number of dof. The confidence interval depends on both.

Response

Doen, chisq/dof=1.14 for 28 degree of freedom.

2) I think the last sentence in the conclusion should say "...decaying to eta pi," rather than eta pi0.

Response

Better to leave as eta pi0

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Bob, 4 Oct

Looks good. I would strongly suggest that we remove the first sentence from the "Conclusion" -- that's a summary-sentence, not needed. Omitting it brings us within an ace of 4 pages.

Also: There's a missing hyphen and comma in the abstract: "mass-dependent fit" "..., and a width ...".

Doen

Bottom-right page 1: "ref. [12]" should be "Ref. [12]",

Doen

There's a missing space between sentences at the very top of page 3, left col.

Gary, Your new paragraph looks a little better, but change "ref. [19]" to "Ref. [19]". I agree that we should say something about IU's result, especially when it is consistent with ours. Cheers, Bob Hackenburg

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Gary Adams, 4 Oct

e852: I have one further comment on draft 6_2. The last full para on page 4, col 1 (Our results...) was added in response to a question I posed in my previous emails. It addresses part of my question and I'm not even sure it needs to be addressed in the paper. The issue is that the IU "moments" fit at low t comes close to our result. They get M=1386+-32 and W=363+-81, with no systematic errors. I was suggesting that we may want to point this out even though they obviously have bogus results at higher t. I'm not sure it is necessary to mention it but what do you folks think? I suggest replacing that para with something like:

"It should also be noted that our result is similar to those obtained from the low-t fits in ref. [19] . They obtained M=1301+-14 and G=190+-32 in one analysis, and M=1386+-32 and G=363+-81 in a fit to the experimental moments. No systematic errors were given for either method."

Response

Comparing these values of IU and our results is not consistent. Low-t in ref. [19], |t|<0.14, don't correspond to all region of t', where we are working. IU fit of moments gives very bad description of P+ intensity and relative phase (P+ - D+) in Fig.22-24 [19]. See also a conclusion in Neal's Note 9.

I think the other option is to leave that para out and not compare with the IU results, as Vladimir had it originally, but I suspect that could lead to some complaints from reviewers. Regards, Gary

Response

It is more correct to mention in our introduction the IU result for all region of t' and for small t' (as in Draft6_2). From these values and our values any reader have to understamd, that IU results in all region of t' are close to us. We have to explain to reviewers our objection about not correct physical solution selection in IU analysis. So their BW parameters may be occaisional parameters. So, I think "to leave that para out" at the end of paper.

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