An international collaboration of scientists recently discovered a new particle, a type of tetraquark.
Quarks are particles that typically come packaged in groups of two or three, and there are six different types or “flavors” of quark. The most recognizable packages are the protons and neutrons, each made of three quarks. The mesons, the glue holding nuclei together, are usually made of two quarks.
While duos and trios of quarks are common, there have only been a few reported tetraquark candidates. The one discovered by the DZero experiment, called X(5568), is the first observed tetraquark to contain four different quark types.
“It’s been a long process starting with atoms, then getting nuclei, then protons and neutrons in the nucleus, then quarks within the proton and neutron, and this is another step in that direction, finding that the mesons are not always as simple as we had originally thought, instead of two there are four [quarks],” said Paul Grannis, Ph.D., a distinguished professor emeritus of physics at Stony Brook University and co-spokesperson for the DZero project. “It changes our picture of how the matter we see around is put together and how many different ways it can be put together.”
The DZero experiment, based at Fermilab, began in 1983 and operated from 1992 to 2011. Scientists are still analyzing the collected data, and the discovery of the new tetraquark comes from analyzing data from proton and antiproton collisions.
The detector used to record the collision events ran for about 10 months in a year, and there were about 10 million events that occurred every second. The challenge for the physicists was to quickly decide which 100 of the 10 million events were unique and rare enough to save.
What began as a funny bump on the computer screen became the discovery of a new type of tetraquark through months of studies and cross-checks.
The discovery has now been submitted for publication and the scientific community is waiting to see if other similar tetraquark particles will be detected at other particle colliders.
Physicists in the team also aim to figure out how the four different quarks are put together to better understand the fundamental physics of the particles that make up the world around us.
FEATURED IMAGE CREDIT: STONY BROOK UNIVERSITY
