Sigma baryon

The Sigma baryons are a family of subatomic hadron particles which have a +2, +1 or -1 elementary charge or are neutral. They are baryons containing three quarks: two up and/or down quarks, and one third quark, which can be either a strange (symbols , , ), a charm (symbols , , ), a bottom (symbols , , ) or a top (symbols , , ) quark. However, the top Sigmas are not expected to be observed as the Standard Model predicts the mean lifetime of top quarks to be roughly . This is about 20 times shorter than the timescale for strong interactions, and therefore it does not form hadrons.