Physics:Upsilon meson

Composition A plot of the invariant mass of muon pairs, from the Upsilon particle discovery paper. The peak at about 9.5 GeV is due to the contribution of the Upsilon meson. bb Bosonic Strong, weak, Electromagnetic, Gravity ϒ Self E288 experiment (1977) 1 9.46030(26) GeV/c2 1.21×10−20 s 0 e 1 0 0 -1 -1

The Upsilon meson (ϒ) is a quarkonium state (i.e. flavourless meson) formed from a bottom quark and its antiparticle. It was discovered by the E288 experiment team, headed by Leon Lederman, at Fermilab in 1977, and was the first particle containing a bottom quark to be discovered because it is the lightest that can be produced without additional massive particles. It has a lifetime of 1.21×10−20 s and a mass about 9.46 GeV/c2 in the ground state.