Particle decay

In <a href="/facts/Particle_physics/YgIuyj2t">particle physics</a>, particle decay is the <a href="/facts/Spontaneous_process/xyGhdUG0">spontaneous process</a> of one unstable <a href="/facts/Subatomic_particle/tMEzcTWQ">subatomic particle</a> transforming into multiple other particles. The particles created in this process (the final state) must each be less massive than the original, although the <a href="/facts/Mass_in_special_relativity/aRloR0nW">total mass</a> of the system must be conserved. A particle is unstable if there is at least one <a href="/facts/Conservation_law/6g1Ay2FR">allowed</a> final state that it can decay into. Unstable particles will often have multiple ways of decaying, each with its own <a href="/facts/Branching_fraction/QrbbS9PI">associated probability</a>. Decays are mediated by one or several <a href="/facts/Fundamental_forces/WrFEJaFl">fundamental forces</a>. The particles in the final state may themselves be unstable and subject to further decay.
The term is typically distinct from <a href="/facts/Radioactive_decay/Ya6FVjt4">radioactive decay</a>, in which an unstable <a href="/facts/Atomic_nucleus/orpIm5Xl">atomic nucleus</a> is transformed into a lighter nucleus accompanied by the emission of particles or <a href="/facts/Radiation/RwMocyeq">radiation</a>, although the two are conceptually similar and are often described using the same terminology.

Particle decay open-in-new

Particle decay