Does this ever happen? p + [itex]\gamma[/itex] [itex]\rightarrow[/itex] n + e^{+} + [itex]\nu_e[/itex] It seems possible, if the [itex]\gamma[/itex] has enough energy, but I wonder if anyone can confirm that it happens.
While I have no idea of whether this could happen in practice, or what the cross section would be, I don't see anything to fundamentally prohibit it. In fact, it strikes me you could look at this as combining two well known interactions that do occur: p + gamma -> p + e+ + e- then, electron capture. Combine, and you get the proposed reaction. This supports the view that there shouldn't be anything fundamental prohibiting this.