Physicists have spent decades organizing the growing collection of subatomic particles, yet some discoveries continue to resist easy classification. Researchers at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility have now identified evidence for two unexpected structures that may help clarify part of this increasingly complicated particle landscape.
The signals could shed light on a puzzling group of objects known as XYZ states. These states do not fit neatly into the conventional picture of particles built from quarks, the fundamental building blocks of matter. For the first time, Jefferson Lab researchers detected two such signals created when a beam of high-energy photons interacted with a proton target.
The findings come from the Gluonic Excitations (GlueX) Collaboration in Experimental Hall D at Jefferson Lab and were recently published in Physical Review Letters. The results could help scientists better understand how one of nature's fundamental forces contributes to the formation of matter.
"We went searching for a confirmed XYZ candidate with a photon beam but instead found two other structures," said Malte Albrecht, a staff scientist at Jefferson Lab. "It's new information."
