(proposed type of particle that might include WIMPs)
A neutralino is a proposed type of particle
in theoretical models termed supersymmetry, in which there
exists another set of particles analogous to known particles
but differ by one quantum number, spin, the difference
being 1/2. The four neutralinos are the result of
quantum mixing of some of these superparticles
(in a similar manner to the mixing of quarks or neutrinos).
Three of the four types of neutralinos would decay quickly,
but the lightest would be stable.
It is a candidate-particle
to serve as a WIMP, because in some
models of the universe's formation (Big Bang nucleosynthesis
in light of supersymmetry),
the total mass of the expected remaining neutralinos
would equal (within reason) the universe's current
total amount of the mass that is credited to dark matter.
This coincidence is termed the WIMP miracle.