E852 experiment
Analysis of Eta Pi0
system with the decay Eta -> Pi+ Pi- Pi0
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Date:
Fri, 16 Sep 2005
From: Minghui Lu
I have some comments and questions.
(1) The author list needs to be updated, both Jingliang ang my name are
not there.
Will be doen
(2) The quoted reference 20 is not E852 paper ( you can see the author
list). I suggest to use something like " In work [20], analysis of
reaction.....was performed by using E852 1994 data".
It is our experiment. Not acceptable analysis by the whole collaboration.
What is other suggestions of this cite?
(3)In data selection, the draft did eta mass cut first, then fit eta
pi0 hypothesis. Have you tried to inverse the order of these cuts, any
difference? When you do the mass cut, how do you deal with the
ambiguity of choosing the right pi0 for eta?
The order of data selection is discribed in Outline and Part 1
(see web site http://www.phy.bnl.gov/~e852/secure/publications.html).
We don't inverse of these cuts. On the level of mass cuts both Pi0
were included. At the second kinematical fit, we hope, the wrong Pi0
is throw out by cut Cl > 0.01. (see Part 1)
(4) why use tprime instead of t for momentum transfer?
t' is more refined variable, it is proportional to sin^2(theta) and used in Regge model.
(5)how did you estimate eta signal to background ratio? Is it mainly
from pi0 selection?
As a ratio squares under Eta signal and side bands. (see Part 1).
(6)On page 3, in the 3rd line, where does this eta^prime pi- come from?
did you mean eta pi0?
Yes, EtaPi0. Will be correct.
(7)I don't quite understand the conclusion here. The peak masses in
two t regions are clearly different. Does the draft indicate two pi1
states? Any possible explanations? The leakage for lower mass pi1 is
not negligible, how can we say it is stable?
Thanks!
The peak mass in two t' regions are the same in the statistic errors.
See Table II.
In the text of draft there are two possible explanations of different mass
Pi1. It should be discussed in collaboration.
The fit results in low mass (< 1.1 GeV) region show the strong leakage
from S0 wave (from strong a_0(980)) at t' < 0.225(GeV/c)^2;
in (mass > 1.1 GeV) region the S0 leakage is absent.
The leakage from D wave is small in both cases (see Fig.5).
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