Last year, a team of nuclear physicists in Hungary observed an anomaly in the decays of excited beryllium-8 atoms — an unexpected preference for spitting out pairs of particles with a particular angle of separation. The bump in the physicists’ data was unmistakable, with odds of less than one in 100 billion of arising by chance. Reporting the anomaly in Physical Review Letters in January, the researchers argued that it could signify the existence of a new fundamental particle. But at first, few took notice.

That changed in April with a much-discussed paper by Jonathan Feng, a theoretical particle physicist at the University of California, Irvine, and colleagues. After spending months translating the nuclear physics finding into the language of particle physics and ensuring that no particle physics experiments contradicted it, the Irvine team determined that the beryllium-8 anomaly is “beautifully” explained by the presence of a previously unknown “vector boson” — a type of particle that would wield a little-felt fifth force of nature.

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