W particles

The electroweak theory predicted three exchange particles, W+, W- and Z0 (neutral), which were 80x as massive as protons and took a large amount of energy to form. An experiment formed them all and found the particles had the expected mass, confirming the electroweak theory.
 Carlo Rubbia, Simon van der Meer Italy and Netherlands 1983 W particles

The electroweak theory predicted three exchange particles, W+, W- and Z0 (neutral), which were 80x as massive as protons and took a large amount of energy to form. An experiment formed them all and found the particles had the expected mass, confirming the electroweak theory.