CMS and Atlas, the two big experimental collaborations at the Large Hadron Collider, have joined forces to produce the most accurate determination of the Higgs boson mass to date. By combining their data sets they obtained
for a relative error of about 0.2%. The paper in Physical Review Letters describing these results has the longest author list ever: 5,154 names. In the published version, there are 9 pages describing the research and 24 pages of authors and their affiliations.
Read the associated APS Physics Viewpoint article here.