researchers have claimed to detect a fifth force (there’s even a Wikipedia page for fifth force possibilities), but the search has really heated up over the past decade. Many scientists think there might be a particle out there called a ‘dark photon’, which could carry a new force that would explain dark matter – that invisible substance that makes up more than 80 percent of the Universe’s mass.
That’s what the Hungarian team, led by physicist Attila Krasznahorkay, were looking for. To do that, they fired protons at thin targets of lithium-7, a collision that created unstable beryllium-8 nuclei, which then decayed into pairs of electrons and positrons.
“According to the standard model, physicists should see that the number of observed pairs drops as the angle separating the trajectory of the electron and positron increases,” Edwin Cartlidge writes for Nature.
But that wasn’t what the team saw – at about 140 degrees, the number of these pairs jumped, creating a little bump before dropping off again at higher angles.
This ‘bump’ was evidence of a new particle, according to Krasznahorkay and his team. They calculated that the mass of this new particle would be around 17 megaelectronvolts, which isn’t what was expected for the ‘dark photon’, but could be evidence of something else entirely.