Which particle was confirmed at CERN in 2012?

The Higgs boson, predicted in 1964 and found 48 years later - which meant Peter Higgs, then 83, lived to see it. He said he had not expected it in his lifetime, and he had famously no email address and had to be told the Nobel news by a neighbour in the street.

What it explains is why anything has mass. The Higgs field is proposed to fill all space, and particles acquire mass by interacting with it - strongly for heavy particles, not at all for the photon. The boson is the ripple in that field, and finding it was the last confirmation the Standard Model needed. Higgs's original paper was rejected by a journal for having no obvious relevance to physics.

The machine built to find it is the largest ever constructed - a 27-kilometre ring under the French-Swiss border, cooled to colder than deep space, colliding protons at close to light speed. The word god particle comes from a book title the publisher chose against the author's wishes; he had wanted to call it the goddamn particle, because it was proving so hard to find. Physicists dislike the name.