The weak force mediates radioactive decay.

The weak W bosons mediate the conversion of a proton into a neutron or vice versa. A neutron consists of an up quark and two down quarks. A proton consists of two up quarks and a down quark.

To convert a neutron into a proton a down quark must be converted into an up quark and a ##W^-## boson. The ##W^-## decays into an electron and an electron anti neutrino.

##d rarr u + W^-## ##W^(-) rarr e^(-) + bar nu_e##

A proton gets converted into a neutron by via the ##W^+## boson.

##u rarr d + W^+## ##W^+ rarr e^+ + nu_e##

Similar processes occur with heavier strange, charm, top and bottom quarks.