[Clascomment] OPT-IN: Measurement of the Sigma Pi Photoproduction Line Shapes Near the Lambda(1405)

[Reinhard Schumacher]

Hello Volker,
	We are adding a sentence to the paper at line 615 to reflect your 
comment.  The "shift" that we see has definitely already gotten the 
attention of the community.  The few-body theorists and the 
chiral-unitary people who heard the talk at the HYP conference last 
October know all about it.  They keep pleading for us to release the 
data so they can do fits to our results.
	The revised paper should be ready to go in a few days.

Reinhard

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Reinhard Schumacher         Department of Physics, 5000 Forbes Ave.
Carnegie Mellon University, Pittsburgh, PA 15213, U.S.A.
phone: 412-268-5177         web: www-meg.phys.cmu.edu/~schumach
___________________________________________________________________

On 01/06/2013 03:45 PM, Volker Burkert wrote:
> This is a very interesting paper of an analysis that tries to disentangle a very complex dynamical problem.
>   I want to congratulate everyone involved. I want to just make one comment.
>
> In my view the main result of the higher level analysis is the conclusion that the centroid of the Lambda(1405)
> I=0 strength is at the pi-Sigma threshold of 1328 MeV with a width of 80+/-20 MeV.  Given the fact that PDG shows
> the Lambda(1405) mass at 1405+/-1 MeV, and its width at 50 +/-2 MeV, the observed "shift" of 77 MeV from our data
> is really spectacular. If we are reasonably sure about this we should make a stronger statement and explicitly say that
> this corresponds to a shift from the PDG mass average by a very large value.  If this is the case, then the 'line-shape'
> issue can be seen also in a very different light. Basically, 50% of the Lambda(1405) strength would be below threshold, so the
> sensitivity to the line shape comes from the higher energy part only, i.e. from the high-energy tail beyond the "peak",
> making such an analysis very difficult as the threshold behavior of the pi-Sigma production would have to be understood
> quantitatively. Perhaps one could discuss these issues somewhat more.
>
> Volker
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