Physicists have finally figured out how pentaquarks are built
Scientists pinpoint the structure of the five-quark particles
To make a quark quintet, combine a trio and a duo.
Exotic subatomic particles called pentaquarks contain five smaller particles called quarks and antiquarks. But those particles aren’t a simple clump of five constituents rattling around. Instead, the pentaquarks are molecule-like agglomerations of a pair of smaller particles, each of which consists of either three quarks or a quark and an antiquark, scientists report in the June 7 Physical Review Letters.
First spotted in 2015 at the Large Hadron Collider in Geneva, pentaquarks were unlike anything seen before (SN: 8/8/15, p. 8). All previous known quark-containing particles were either baryons — particles such as protons and neutrons which contain three quarks — or mesons, which consist of one quark and one antiquark. But pentaquarks, with their five component particles, didn’t fit into either of those categories.