[Clascomment] OPT-IN:Beam-Recoil Transferred Polarization in K+Y Electroproduction in the Nucleon Resonance Region with CLAS12

[David Ireland]

Hi Daniel, et al.,

Congratulations in getting to the point of publishing CLAS12 results on Kaon electroproduction. This is an impressive paper that clearly describes the background, data collection and analysis, as well as providing a good narrative on the new challenges to theoretical models.

I do have a couple of related comments that I am afraid may sound like I am blowing my own trumpet!

1.The CLAS kaon photoproduction papers containing results on K-Lambda and K-Sigma observables are rightly identified, but seem to have missed out the paper on g8 data:

@article{Paterson:2016vmc,
      author         = "Paterson, C. A. and others",
      title          = "{Photoproduction of $\Lambda$ and $\Sigma^0$ hyperons
                        using linearly polarized photons}",
      collaboration  = "CLAS",
      journal        = "Phys. Rev. C",
      volume         = "93",
      year           = "2016",
      number         = "6",
      pages          = "065201",
      doi            = "10.1103/PhysRevC.93.065201",
      eprint         = "1603.06492",
      archivePrefix  = "arXiv",
      primaryClass   = "nucl-ex",
      reportNumber   = "JLAB-PHY-16-2293",
      SLACcitation   = "%%CITATION = ARXIV:1603.06492;%%"
}

These (g8) data were a critical part of the more recent Bonn-Gatchina and Juelich-Bonn analyses (the Anisovitch et al paper [13] is cited, for instance), which have in turn fed into the PDG listings.

2. In lines 267-269, the text reads "The Lambda weak decay asymmetry parameter α has been measured to be 0.732±0.014 [14]". Er,... not quite! This is the value quoted in the current PDG listings, and is certainly the right value and uncertainty to use in the present analysis, but represents an average of two recent evaluations from BES and CLAS! Again, I have inside knowledge of the latter:

@article{PhysRevLett.123.182301,
  title = {Kaon Photoproduction and the $\mathrm{\ensuremath{\Lambda}}$ Decay Parameter ${\ensuremath{\alpha}}_{\ensuremath{-}}$},
  author = {Ireland, D. G. and D\"oring, M. and Glazier, D. I. and Haidenbauer, J. and Mai, M. and Murray-Smith, R. and R\"onchen, D.},
  journal = {Phys. Rev. Lett.},
  volume = {123},
  issue = {18},
  pages = {182301},
  numpages = {6},
  year = {2019},
  month = {Oct},
  publisher = {American Physical Society},
  doi = {10.1103/PhysRevLett.123.182301},
  url = {https://link.aps.org/doi/10.1103/PhysRevLett.123.182301}
}

So we may be missing two opportunities in this paper to reinforce the message that previous CLAS data has been influential in the field. Otherwise, the paper should be an important contribution, and is a strong indication that results from the CLAS12 detector will have a lot to say in resonance physics. 

Cheers,

Dave