Fifth Force of Nature
A fifth force of nature may have been discovered by scientists at the Institute for Nuclear Research at the Hungarian Academy of Sciences (Atomki). The team was closely monitoring how an excited helium atom emitted light as it decayed, and the particles ended up splitting at an unusual angle, 115 degrees, which couldn’t be explained by known physics. They called this new particle X17 because they calculated its mass at 17 megaelectronvolts. Read more for a video and additional information.

Around three years ago, these Hungarian researchers published a similar paper in Physical Review Letters, as they were studying another isotope, beryllium-8, as it decayed down to a ground state. They saw electrons and positrons splitting off from the atom at around a 140-degree angle.

We introduced such a new particle, which nobody saw before, and which existence could not be understood by the widely accepted ‘Standard Model’ of particle physics, so it faced scrutiny,” said Attila Krasznahorkay, the study’s lead scientist.