hyperon

A hyperon is a theorized composite particle (a hadron) that would have 1/2 spin (and obey Fermi-Dirac statistics, i.e., a fermion) that consists of an odd number of quarks (a baryon), in which at least one is a strange quark and each of the others is an up quark or down quark. Of the theorized types of hyperons (i.e., the possible quark flavor combinations), some would decay immediately, in some cases into more familiar baryons. Some particle physics theories predict the possibility of hyperons and they are searched for in particle accelerator experiments. Matter consisting of hyperons (hyperonic matter or hyperon condensate) is considered a possibility within some neutron stars, where hyperons may be a factor in their cooling through reactions that produce neutrinos, the latter of which may sometimes escape the star with their energy.