More than 50 hadrons discovered at the LHC
The LHC was designed primarily to search for high energy phenomena produced in its proton-proton collisions. But those collisions also provide an unprecedented source of lower energy hadronic particles (bound states of quarks). The LHC data has to date allowed the observations of more than 50 new hadrons, as illustrated in the figure. These include discoveries of unexpected new types of hadron with four or five quarks bound together (so called tetraquarks and pentaquarks) -- all previously known hadrons were made of either two or three quarks (called mesons and baryons, respectively). The majority, but not all, of these discoveries have been made by the LHCb collaboration, in which the Warwick group has a leading role. Indeed, Warwick researchers have been directly involved in 12 of these discoveries to date. With more work in the pipeline, the LHC is rapidly becoming established as a unique hadron discovery factory.
- Caption to figure: New hadrons discovered at the LHC. More detailed information is available at https://www.nikhef.nl/~pkoppenb/particles.html