After multiple false detections, physicists have now confirmed in a pair of studies the existence of subatomic particles known as 'pentaquarks'.

In the standard model, particles called baryons, which make up most of the visible matter in the Universe and include protons and neutrons, are built from three fractionally charged objects called quarks. Theorists have predicted that quarks could aggregate into larger groups and have speculated for years about the short-lived pentaquark, composed of four quarks and an antiquark. Now researchers at the LHCb experiment at CERN's Large Hadron Collider near Geneva, Switzerland, have come up with the most convincing evidence yet for this exotic particle.

In one study, the authors reanalysed previous particle-decay data while reducing their model's assumptions. They showed at extremely high statistical significance that pentaquarks are needed to explain the data. In the second study, the researchers examined data from a particular kind of decay, finding that they are in line with predictions of decays involving pentaquarks.

Phys. Rev. Lett. http://doi.org/bpsc; http://doi.org/bpsb (2016)