Kaon
![The decay of a kaon (K+) into three pions (2 π+, 1 π−) is a process that involves both weak and strong interactions.Weak interactions : The strange antiquark (s) of the kaon transmutes into an up antiquark (u) by the emission of a W+ boson; the W+ boson subsequently decays into a down antiquark (d) and an up quark (u).Strong interactions : An up quark (u) emits a gluon (g) which decays into a down quark (d) and a down antiquark (d).](/Images/godic/202501/22/Kaon-decay1555.png")
![Two different neutral K mesons, carrying different strangeness, can turn from one into another through the weak interactions, since these interactions do not conserve strangeness. The strange quark in the anti-K0 turns into a down quark by successively absorbing two W-bosons of opposite charge. The down antiquark in the anti-K0 turns into a strange antiquark by emitting them.](/Images/godic/202501/22/Kaon-box-diagram-with-bar.svg1556.png")
In particle physics, a kaon /ˈkeɪ.ɒn/, also called a K meson and denoted K, is any of a group of four mesons distinguished by a quantum number called strangeness. In the quark model they are understood to be bound states of a strange quark (or antiquark) and an up or down antiquark (or quark).