High-energy tail of H electron momentum distribution? 1/p^6?

[jarekduda]

Kind of the basic question of atomic physics is momentum distribution of single electron of ground state hydrogen atom - especially the power in its high-energy tail (HTMD: high-tail momentum distribution), which should have strong impact especially on various scattering experiments.
Fock's 1935 non-relativistic quantum derivation leads to 1/p^6 tail.

However, I have recently found a 2001 Eugene Oks paper with a long list of references claiming that experiments suggest "heavier tails": much lower power, like 1/p^4 or even lower:
http://iopscience.iop.org/article/10.1088/0953-4075/34/11/315/pdf
e.g. "The point we are trying to make is that the above fundamental dispute still remains unresolved: the experiments seem to favour a HTMD of ∼1/p^k , where k is at least 1.5 times smaller than in the quantum HTMD."

So I wanted to ask which power should be used to describe the real ground state hydrogen atom?

 

[Paul Colby]

So, why use a non-relativistic derivation? I assume the high energy tail in momentum space corresponds to or is driven by the region near the nucleus. Since the relativistic ground state of hydrogen (solution of the Dirac equation) is known in closed form, (Bojorkin and Drell Vol 1 page 55) I would think this is a solvable problem.