On January 25 in 1983 physicists announced the discovery of the W boson at CERN. This was the culmination of work proposed in 1976 by Carlo Rubbia, David Cline, and Peter McIntyre to convert CERN Super Proton Synchrotron (SPS) a proton accelerator, into a proton anti-proton collider. Based on this proposal two experiments UA1 and UA2 where build and eventually found not only the W boson but shortly after also the neutral Z boson complement to complete the discovery of the weak mediators (youtube story on the W boson discovery: part I, part II). The Cylindrical Onion, a CMS News outlet, has published a nice article by our own Guillelmo Gomez-Ceballos discussing the anniversary of the W boson.
While at the observation in 1983 barely visible signals were painstakingly extracted and rewarded with the Nobel Prize 1984, the W and Z bosons were studied with high precision at LEP which cemented the Standard Model of Particle Physics and again for the detailed description of their nature lead to the Nobel Prize 1999. At hadron colliders ever since their discovery the Z and W bosons served as standard candles allowing for detailed calibration of the detectors but eventually in particular the less well measured W boson mass became a major topic as a physics measurement. Due to our precise knowledge of the Fermi coupling constant, the very precise Z boson mass measurement, and our in depth understanding of radiative corrections the W boson mass can be predicted much more precisely than it has been measured so far. Any disagreement between measurement and prediction would imply the existence of New Physics.
The recent measurement of the W boson mass by the CDF experiment is by far the most precise measurement to date and disagrees with the prediction by seven standard deviations. Another very precise measurement has become a high priority for the community and the LHC collaborations are gearing up to make their contributions. Our group, the PPC at MIT, has made the precise W boson mass measurement a major priority in CMS and we hope in the year of the 40th anniversary of its discovery to add to this exciting story. The CMS collaborators interested in the W mass measurement have had an intense January to make a schedule and also to discuss a long term plan to push beyond the precision so far reached.