Baryon Periodic Table

Baryons are particles made of three quarks. The particles can exist in a ground state (J=1/2) and an excited state (J=3/2). The CDF experiment has discovered the positively charged Sigma_b⁺ and the negatively charged Sigma_b^- in both spin configurations. This figure shows the various three-quark combinations with J=3/2 that are possible using the three lightest quarks -- up, down and strange -- and the bottom quark. Past experiments discovered all of the baryons made of light quarks. The CDF discovery is the first observation of baryons with one bottom quark and spin J=3/2. Theory predicts four more such particles to exist. There are additional baryons involving the charm quark, which are not shown. The top quark, discovered at Fermilab in 1995, is too short-lived to become part of a baryon.

Reported by: Scientists at the Fermi National Accelerator Laboratory (see the Fermilab press release)

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