...Or at least, signs point to the potential for a previously unobserved particle. Theoretical physicists at the University of California, Irvine, built on a 2015 study by Hungarian researchers, that saw "an excess of events that indicated a new particle," and proposed that instead of this being a dark photon, as the original Hungarian study sought to uncover, that it could instead be the elusive "protophobic X boson" — a particle that only interacts with electrons and neutrons, instead of the electromagnetic combo of electrons and protons. Their work was published in Physical Review Letters this month.