[Clascomment] comments on The Beam-Target E asymmetry for vec gamma vec n -> pi- p in the Nâ resonance region

[Eugene Pasyuk]

Concerning SAID band. Another option of presentation could be cross section weighted average over a bin. The experimental data points are exactly this.

-Eugene

----- Original Message -----
> From: "Andrew Sandorfi" <sandorfi at jlab.org>
> To: "Eugene Pasyuk" <pasyuk at jlab.org>, "clasmbr" <clasmbr at jlab.org>, "clascomment" <clascomment at jlab.org>, "Daniel
> Carman" <carman at jlab.org>, "Michael Dugger" <dugger at jlab.org>, "Kyungseon Joo" <kjoo at phys.uconn.edu>, "Alexandre Deur"
> <deurpam at jlab.org>, "Patrick Collins" <pcollins at jlab.org>, "Charles Hanretty" <charleshanretty at gmail.com>, "Tsuneo
> Kageya" <kageya at jlab.org>, "Annalisa D'Angelo" <annalisa.dangelo at roma2.infn.it>, daoh at jlab.org, jamief at jlab.org,
> cbass at jlab.org, "Peng Peng" <pp9e at virginia.edu>
> Sent: Wednesday, March 15, 2017 7:13:53 PM
> Subject: Re: comments on  The Beam-Target E asymmetry for vec gamma vec n -> pi- p in the Nâ resonance region

> Hi Eugene,
> Thanks for the comments. My actions/responses are embedded below.
> Andy
> 
> 
> 
> 
> On 3/15/17, 3:48 PM, "Eugene Pasyuk" <pasyuk at jlab.org> wrote:
> 
>> Several comments.
>> 
>> page 2 Fig. 1 caption: replace distance -> position
> ________________
> Done
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> 
> 
>> 
>> page 2, column 1:  in "Here we report...." I would move equation "of E=..."
>> right after "... double polarization measurements..."
> ________________
> Done
> ________________
> 
> 
>> 
>> page 2, column 2: "...retains about 25% more events..." more compared to what?
> ________________
> Compared with the Bksub procedure, with which it is contrasted in the
> beginning of that paragraph.
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> 
> 
>> 
>> page 3 : in two places where you talk about extrapolation to P_miss=0 use
>> "systematic uncertainty" instead of "systematic error"
> ________________
> Done
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>> 
>> Fig. 4. There is an inconsistency in how SAID and BnGa curves are presented.
>> SAID curves go all the way to the extreme angles of 0 and 180 degrees while
>> BnGa are truncated at experimental points. Perhaps it makes sense to truncate
>> SAID the same way.
> ________________
> The BnGa group provided their fitted expectation values for E only between
> the angles of our data set. The SAID group provided the full range. I don't
> see an advantage in showing less information. On the other hand, there is
> one advantage in showing the full range for at least one of the two PWA,
> namely to demonstrate that the curves indeed do go to +1 at the 0 and 180
> deg limits as required by symmetry, even though the transition can be very
> rapid at small angles.
> ________________
> 
> 
>> Also showing SAID as a band is somewhat ambiguous. It is not obvious which
>> side of the band correspond to the upper and lower edge of the bin.
> ________________
> The side of the band corresponding to the upper or lower limits doesn't
> really matter. (In fact, at some energies they cross over.) Recall how these
> are generated. These curves are from an Energy-Dependent PWA, which is a
> smooth fit to a set of Energy-Independent solutions. The latter are made by
> binning the world's data in W and assigning all measurements within a
> particular bin to the centroid energy of that bin, even though all those
> data were not taken at exactly the same energy. So there is an inherent
> energy uncertainty in this PWA process. Showing the spread of predictions
> for the limits of our \pm 20 MeV bins is a way of indicating the approximate
> effect of this PWA uncertainty.
> ________________