The W particle was discovered in 1983 by teams led by Carlo Rubbia and Sim van der Meer.  This discovery confirmed the Electroweak Theory (which explains that the electromagnetic force and the weak force are manifestations of the same interaction)!  The weak force is excahnged through three tpes of particles, one of these particles is neutral, and the other two are charged.  The charged particles are detonated by W+ and W- according to the sign of their charge.  The neutral particle is known as the Z particle.  The W particle has a mass about 80 times that of the proton which gives the weak force a very short range.