Steven.. I noted that Peter Hagelstein,MIT may not been at Szczecin for your presentation about the WL model?
As you noted Hagelstein wrote in 2013..
" This model is the single most successful theoretical model that the field has seen since it started;"
but there was a lot more written.. 22 pages..
it has served as the theoretical justification for a program at NASA; ...
The first step in the model involves the proposed accumulation of mass by electrons through Coulomb interactions with electrons and ions in highly-excited coupled plasmon and optical phonon modes.
Historically for us this mass increase has been hard to understand, so we were motivated in this study to understand better how this comes about. To study it, we consider simple
classical models which show the effect, from which we see that the mass increase can be associated with the electron kinetic energy.The basic results of the simple classical model carry over to the quantum problem in the case of simple wave packet solutions. Since there are no quantum fluctuations of the longitudinal field in the Coulomb gauge, the resulting problem is conventional, and
we find no reason to expect MeV electron kinetic energy in a conventional consideration of electrons in metals.
We consider the numerical example outlined in a primer on the Widom–Larsen model,
and find that multiple GW/cm2 would be required to support
the level of vibrational excitation assumed in the surface layer;
this very large power per unit area falls short by orders of magnitude the power level needed to make up the expected energy loss of the mass-enhanced electrons.
We note that the mass enhancement of an electron in a transverse field is connected to acceleration, so that the electron radiates.A similar effect is expected in the longitudinal case, and
a very large amount of easily detected X-ray radiation would be expected if an MeV-level mass enhancement were present even in a modest number of electrons.
At the end of his detailed paper Hagelstein wrote..
Presumably Widom and Larsen will clarify things in their future publications.
I was wondering if Widom and Larsen did " clarify things" ,especially the matters highlighted in blue..
https://www.iscmns.org/CMNS/JCMNS-Vol12.pdf
P.L. Hagelstein / JCMNS12 (2013) 18–40