OPT-IN: Beam-Target Helicity Asymmetry E in K+룉 Photoproduction on the Neutron

[David Ireland]

Hi Nick et al., 

Good to see that this data is going to be published. I have a few comments on the draft that you may like to consider:

* Abstract, Line 29: "improvements in the $\chi^2$ fit". I don't see any mention of the different values of this statistic in the text, so a re-write of this sentence or a discussion of the fit values would be in order.

* line 56-57: "Kinematically complete measurements" This phrase is ambiguous. It could mean the measurement of the kinematic variables required to identify a specific channel, or is could be referring to a "complete" measurement of observables that is required to extract amplitudes. If it is the latter, then one should note that the "completeness" is only a mathematical construct and that the accuracy of the measurements needs to be sufficient, as noted in reference [15].

* Line 74: You should include Paterson et al (Phys. Rev. C, 93 (2016), p. 065201) in the list of CLAS references for kaon photoproduction results.

* Equation (1); The recent review "Photoproduction reactions and non-strange baryon spectroscopy" Ireland, Pasyuk and Strakovsky (https://doi.org/10.1016/j.ppnp.2019.103752) contains cross section and asymmetry expressions for the combinations of beam, target and recoil polarization. Since you measure the pi- from the Sigma decay you are automatically sensitive to both recoil polarization P and double H as well as E (eq 13d in that review paper). You may need to add that it is only possible to ignore these observables (P,H) because of the low value of the \Sigma- decay constant (0.068).

* Line 274: the the -> the

* Line 295: are explored -> is explored

* Line 377: data is -> data are

* Line 389: "missin"" -> "missing" 

* ref [41]: Flemings -> Fleming

Best wishes

Dave