Upsilon meson

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 collaboration, 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.

See also

• Oops-Leon, an erroneously-claimed discovery of a similar particle at a lower mass in 1976.
• The ϕ particle is the analogous state made from strange quarks.
• The J/ψ particle is the analogous state made from charm quarks.
• List of mesons