The Delta Baryon

The delta is a baryon which contains only up and down quarks. The Δ⁺ and Δ⁰ have the same quark compositions as the proton and neutron respectively and decay quickly by the strong interaction to the proton and neutron and a π⁰. If such a decay pathway is available to a particle, it decays very quickly - on the order of 10^-23 seconds. Another example is the decay Δ⁰ --> p⁺ + π^-. Note that the delta baryon Δ⁰ has the same quark makeup as the neutron, but its mass is much larger. Its mass is sufficient for this decay to be energetically favorable. The four varieties have similar masses and are said to be an isospin quartet.