[Clascomment] OPT-IN: Subthreshold photoproduction of phi mesons from deuterium

[Reinhard Schumacher]

Hello Haiyan et al.,

After some more thought, I may understand what your E_gammaboost
cut is doing.  The paper says the selection of events with
E_gammaboost > 1.75 GeV keeps events from the high momentum tail of
the deuteron \"wavefunction\", which ought to be the main contributors
to the event sample you have.  Also, the cut limit of 1.75 GeV is
imposed AND the upper lab energy of the photon is 1.75 GeV (which is
not quite clear from the wording).  This raises the questions:

1) Why don\'t you cut directly on the reconstructed proton momentum?
   Is that not a much more natural, and explainable, variable to use?

2) Why is the E_gammaboost cut made at the same numerical value as the 
   upper limit of the lab photon energy?  This is in part why I was so
   puzzled for a while: the way the discussion is worded it implies
   there may be a connection, but you never explain it.  How sensitive
   is your result to this cut?  That is, what if the limit were 1.57
   or 2.0 GeV?  How would your answer change?

3) Why do you need this cut in the first place?  It would seem that
   any lower-momentum protons in the deuteron would simply result in
   events that fall outside the fiducial acceptance anyway, so it is
   not made clear what the action of this additional selection is.


I think you owe it to the reader to explain these things in the paper.

Best Regards,
Reinhard.