Mysterious Subatomic Particle May Represent Exotic New Form of Matter
The intriguing discovery was made more or less simultaneously by two collaborations: the Belle experiment at the Japanese High Energy Accelerator Research Organization (KEK) and BESIII experiment run by the Institute of High Energy Physics (IHEP) in China.
The Belle detector in Japan.
Both teams were looking at a particle called Y(4260) that had been discovered in 2005 but whose nature has mystified researchers since. By smashing together electrons and their antiparticle, positrons, the experiments produced large numbers of Y(4260), which lives for only 10-23 seconds before falling apart into other particles. The teams noticed that their data had a peculiar bump around 3.9 megaelectronvolts (MeV), an energy corresponding to roughly four times the weight of a proton.
“Inspired by this discovery, we decided to further study the Y(4260) decay, which indeed did not disappoint us,” said particle physicist Zhiqing Liu, lead author of a paper from the Belle experiment that appeared in Physical Review Letters on June 17. A second paper from BESIII, of which Liu is also a member, appears in the same issue.
The teams have enough data to conclude they have discovered something new, a putative particle named Z(3900). But the scientists are still not entirely sure what to make of it. One possibility is that Z(3900) represents a subatomic structure made of four quarks, something that has never been solidly seen before.
Read the full article at: wired.com