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Different interactions

Strong, electromagnetic, and weak interactions all cause particle decays. However, only weak interactions can cause the decay of fundamental particles.

Weak Decays:

Only weak interactions can change a fundamental particle into another type of particle. Physicists call particle types "flavors." The weak interaction can change a charm quark into a strange quark while emitting a virtual W boson (charm and strange are flavors). Only the weak interaction (via the W boson) can change flavor and allow the decay of a truly fundamental particle.

Electromagnetic Decays:

The 0 (neutral pion) is a meson. The quark and antiquark can annihilate; from the annihilation come two photons. This is an example of an electromagnetic decay.

Strong Decays:

The particle is a meson. It can undergo a strong decay into two gluons (which emerge as hadrons).
The strong force-carrier particle, the gluon, mediates decays involving color changes. The weak force-carrier particles, W+ and W-, mediate decays in which particles change flavor (and electric charge).