Workings of the weak forces
Quantum mechanics allows a particle to undergo brief transformations, provided it returns to its original state. This is how the neutron can occasionally appear as a proton accompanied by a negatively-charged object called ‘W boson’. During the tiny fraction of a second that these two particles exist, the W boson may decay into an electron and an antineutrino. The probability of the intermediary stage combined with the probability of the W boson decaying is so low that the proton-neutron (or neutron-proton) transformations are found to be very slow, and for this reason the interaction has been dubbed ‘weak’. The W boson was observed as a particle for the first time at CERN in 1983.