Is partial neutrino a boson in disguise?

摘要

A particle proposed 50 years ago may be masquerading as a fraction of a neutrino. The Goldstone boson is supposed to be part of the Higgs mechanism, which gives mass to other particles. But no hints of it had been seen in nature. High-resolution maps of the early universe make the most sense if there are between three and four types of neutrino. We know of only three. The Goldstone could fill the gap, says Steven Weinberg of the University of Texas at Austin. It is its own antiparticle, so would have halftheeffectofaparticle pair on the maps. And interacting less with matter as the universe expands means it could look like 0.39 of a neutrino (Physical Review Letters, d0i.org/m2s).