Resonance (particle physics)

In particle physics, a resonance is the peak located around a certain energy found in differential cross sections of scattering experiments. These peaks are associated with subatomic particles (such as nucleons, delta baryons, upsilon mesons) and their excitations. The width of the resonance (Γ) is related to the lifetime (τ) of the particle (or its excited state) by the relation

where h is the Planck constant and ℏ = h 2 π .