[Clascomment] OPT-IN: Transverse Polarization of Sigma+(1189) in Photoproduction on a Hydrogen Target

[Chandra Nepali]

Hi Volker,

Thank you very much for your comments and suggestions. We will work on this.

Chandra

On 12/22/2012 11:10 AM, Volker Burkert wrote:
> Hi Chandra, 
>
>  It is good to see that the CLAS data have sufficient statistical sensitivity to show 
> real interesting behavior. I have a few comments about this and some suggestion.
> Several readers have already commented on other aspects of the paper, with which
> I agree,  and I will not repeat those here. However, I want to point out that in Table II and Table 
> III on page 9 your energy bins, that you give as +/- 0.167 GeV are twice as large as they should
> be. For example you show in the 1st bin E=1.25+/-0.167 and the 2nd bin E=1.42+/-0.167,
> which means your 2nd bin reaches down to the center of the first bin rather than to the upper
> limit of the 1st bin. All bins should be +/-0.0835GeV. 
>
>
>
>   
> Here is my main comment:
>
> The introduction refers to the "missing resonances" problem. I think this is exactly what 
> you should be focussing on. Unfortunately, you neglect to reference some of the recent 
> publications that claimed evidence for new baryon states particular using the new CLAS
> data on hyperon production (K-Lambda, K-Sigma) and the polarization data for these 
> channels. The publications you should be referring to are from the Bonn-Gatchina group:
>  A.V. Anisovich, et al., Eur.Phys.J.A47 (2011) 153 and Eur.Phys.J.A48 (2012) 88. The latter 
> shows a table with the coupling to KY final states of some newly claimed nucleon resonances
> in the mass range of 1.9 - 2.1 GeV, several of which made it in the PDG 2012 including
> states coupling to K-Sigma.   
>
> Your discussion in section VIII. completely neglects a discussion of the nucleon resonance 
> aspects and only discusses aspects that have nothing to do with resonance formation. The 
> only comment where the resonance region is indirectly mentioned ins in the comment 
> that there are "systematic differences of about 1 (in polarization) at sqrt(s)=2GeV".
> Indeed this is very significant and the fact that the transverse polarization is qualitatively 
> different where evidence for new resonances has been seen and published should be 
> mentioned. I suggest to add one or two graphs showing the very different behavior of
> the polarization in the "resonance" regime and the "DIS" regime. If you plot the polarization 
> in Table IV, at the Eg=1.62GeV (sqrt(s)=1.97GeV) bin versus the cm polar angle of the Sigma^+ 
> you will see a variation from P=-1.08 to P=+0.34 in the angle range covered. If you plot
> the same at the bin Eg=3.12GeV (sqrt(s)=2.55GeV) you find the polarization to remain 
> negative between -0.43 and -0.91.  
> This different behavior is highly significant. It shows that there is NOT one mechanism that 
> could explain the main observations, even not qualitatively. You discussion should 
> emphasize this difference and conclude that your data may have significant impact
> on the search for new nucleon resonances once it included in a coupled channel analysis.     
>
> BTW, I would prefer the data be listed and plotted vs sqrt(s) as they cover mostly the resonance 
> region, where resonance masses are identified as sqrt(s). Maybe you can add 
>
> Volker
>