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• The Higgs field does something strange: throughout the
entire Universe, it takes on a uniform, non-zero value.
• When the Higgs field does this, the interactions between
the Higgs boson and other particles acquire their mass.
• If the Higgs field didn't do this, all particles would be
massless (some small technicalities that I'm glossing over).
• The Standard Model of Particle Physics describes all the
known properties of nature (with the exception of dark
matter).
• To know how the Higgs boson behaves, you have to know
the Higgs boson mass (i.e. the mass is not a prediction of
the theory).
• The only thing you have to specify is the mass of the Higgs
boson, after that, all interactions of the Standard Model
are fixed, and you can make predictions to arbitrary accuracy
(though it is very hard practically).
• Therefore, the searches for the Higgs boson always left the
mass as a free parameter.
• Before July 4, 2012, the Higgs boson mass could only be in
the 122 GeV to 130 GeV mass range (units where the proton
mass is about 1 GeV, and the W and Z vector bosons
are 80 GeV and 90 GeV, respectively). There was a small
excess from the December 2011 results at 125 GeV. Many
people suspected that the excess was the Higgs boson.
• on July 4, 2012, the experiments showed that this excess
grew substantially with the additional data that was recorded
in 2012.
• each experiment reached the "5 sigma" discovery threshold,
which means that if there wasn't something there,
it would be a fluke that would occur 1 time in 3,000,000
chances.
• There are two general purpose experimental collaborations
at the LHC, each of which has 3000 physicists working.
They are called ATLAS and CMS.
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