Phys. Rev. Lett. (in the press); preprint at (2014)

Using data from CERN's Large Hadron Collider, the ATLAS Collaboration has collected evidence of a process known as vector boson scattering (VBS). The vector boson in question is the W boson, discovered at CERN in the early 1980s. Now, ATLAS has identified an excess of events — in a 20.3 fb−1 sample of proton–proton collisions at a centre-of-mass energy of 8 TeV — that is consistent with the scattering of two W bosons, each having been radiated from the quarks inside the colliding protons.

By seeking a particular signature of VBS — of two same-electric-charge W bosons decaying to a neutrino plus either an electron or a muon, and accompanied by two jets of particles — the physicists were able to home in on the 'electroweak' class of VBS processes, and compare their cross-sections with the standard-model predictions. The now-discovered Higgs boson is a vital part of the theory, keeping the VBS amplitude under control (lest unitarity break down at the TeV scale). However, VBS is still usefully sensitive to 'new physics' — but, almost inevitably, ATLAS conclude that all is in line with the standard model.