But the most precise measurement yet of the fine structure constant — which determines how strongly electrons and photons interact, or “couple” — has eliminated the possibility of dark photons at a large range of masses and coupling strengths. If they did exist, they would have to be much heavier than previously predicted, scientists wrote in a new paper describing the work.
One possible hope:
However, there’s still a narrow escape path, through which theoretical dark photons could escape the dustbin of discarded physics theories. The field of particle physics has a general standard for measuring the significance of results: Typically, a truly significant resultmust have less than a 1-in-3.5-million probability of being due to random chance, which is a “5-sigma” level of significance. In this case, the difference between this measurement and the previous most-precise measurement is only a “2.5-sigma” level of significance, or a 1-in-200 probability of being due to random chance — far too likelyto meet thestrong standard of the field. Meredith Fore, “Dark Photons Probably Don’t Exist, and If They Did, They’d Be Super Weird” at LiveScience
Realistically, the Standard (Big Bang) Model of the universe is not in anywhere near enough trouble for this stuff to seem credible, though it is fun to look at.
See also: Scientists hunt mysterious “fifth force” that would “change paradigm”