lambda baryon

(physics) A hypothetical particle having physical quantities on the Planck scale, most importantly being one Planck mass in mass.

A photon with a wavelength short enough to be considered a gamma ray, usually emitted from radioactivity.

alpha particle

(physics) A fermion that is its own antiparticle and thus capable of self-annihilation.

(informal) The Higgs boson.

(physics) Any of the subatomic particles that does not consist of other, smaller particles; the gauge bosons, leptons and quarks.

(physics) A positively charged nucleus of a helium-4 atom (consisting of two protons and two neutrons), emitted as a consequence of radioactivity; α-particle

Any of many units of matter smaller than an atom.

(physics) An energetic electron or positron produced as the result of a nuclear reaction or nuclear decay.