page_title: Upsilon meson
hierarchical_section_title: Upsilon meson
context_page_description: The Upsilon meson is a quarkonium state 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.
context_section_description: 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.
caption: 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.
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