[Clascomment] OPT-IN: Momentum sharing in imbalanced Fermi systems

[Sebastian Kuhn]

I think that this paper presents an interesting and important experimental finding - namely that the contribution of pp pairs to the high momentum tail of the nuclear WF is much smaller than that of pn pairs (and even falling) out to the highest A. I would have preferred to focus on this finding, and give clear limits (including all experimental uncertainties, uncertainties of FSI, and estimates of nn/pp) for the total fraction of nn, np and pp pairs in different nuclei. I suspect that the results are consistent with them being all quite constant with A, which would be important to state (with full 1-sigma confidence interval).
>From there, the next step is to state the effect on the average kinetic energy, which is increased for protons simply because there are (nearly) equal amounts of them at high momentum as n, but a lot fewer at low momentum. It might be appropriate to put that table (S-II and S-III) into the main text, but without all the details (different models etc.) and instead with realistic 1-sigma limits based on the same data (i.e., on MEASURED nn, np and pp probabilities, without setting either one to 0 or 1).

I am less in favor of the strong emphasis on comparing different Fermion systems, which basically is the introduction (and therefor the apparent focus) of the paper. For one, I believe the momentary leveling off between (1.5 and 2.5 x 250 MeV/c) of p^4*n(p) for the deuteron is more or less an artifact (a consequence of the fortuitous cancellation of the zero crossing for the s-wave and the peak of the p-wave, which are due to different mechanisms). I think it's fine to speculate that cold-atom experiments with unbalanced 2-fermion systems would give similar results, but I think overall that angle is emphasized too heavily.

I will send, in separate email, my proof copy of the paper with comments, and a plot that shows the point I'm making about the deuteron, to the lead authors.