Maybe this article is a model for an extension of "Proposed mechanisms" ... which, for Cold Fusion, seems to be frozen at about 2004  http://en.wikipedia.org/wiki/High_temperature_superconductivity#Possible_mechanism  giving a fairly clear review of another case where the effect is established, but there is no single agreed theory:  There have been two representative theories for HTS ... (And I won't even suggest looking at theories of big-bang inflation, where there's been a paper a day for 20 years and still no agreement.)