[Clascomment] OPT-IN: Beam-Target Helicity Asymmetry E in K+ÎŁâ Photoproduction on the Neutron

[nicholas]

Dear Axel, 

Thank you for your feedback and comments. The high-rate of beam helicity flipping results in a statistically insignificant flux asymmetry for the two configurations (beam helicity parallel to target pol and beam helicity antiparallel to target pol) and thus no normalisation is needed. For this an event weighted average of the target polarisation was calculated. Furthermore, the observables E was also determined using an event-by-event maximum likelihood approach and the two procedures yielded identical results.

Background contributions were estimated and accounted for using simulated data. The diffused background primarily originates from accidentals as well as events where the Kaon decayed in flight. The contribution for both of these were very small on a bin-by-bin case and was thus neglected. Systematic uncertainties related to background contributions were estimated however and included in the total systematic uncertainty. 

Thank you again for your comments; I will add a few sentences to clarify things a bit more. 

Best regards, 
Nick

> On 22 Feb 2020, at 20:30, Axel Schmidt <schmidta at jlab.org> wrote:
> 
> Dear Nick et al., 
>    Congratulations on this result. I enjoyed reading the paper. I wish I could give you more helpful substantive comments but this is all I got. May it be helpful,
> Axel
> 
> - In equation 2, you define the asymmetry by flipping one polarization (beam or target) and keeping the other fixed. But during the experiment, you had four configurations: two photon helicities, two target polarizations. You even say, starting in line 148, that flipping both is good for reducing systematics. But you don't say how you combined the yields of the four configurations into one extraction of E. If you measure the asymmetry, A, for two target polarities, do you average them, take the geometric mean, or do some other procedure?
> 
> 
> - In Fig. 2, it looks like the signal channel, while well-separated from the other discrete background channels, sits on top of a big diffuse background. Do you have a way of estimating that? Was it a problem at all?
> 
> 
> - I notice that 'Quark' is capitalized on line 69, but lower case on p.1, (e.g. line 35).