Higgs particle discovered

Finally! At long last! This long-sought particle has been discovered, or at least some approximation of it. It’s the last remaining particle of the Standard Model, and it makes all the other ones massive except for the photon and the gluon.

Higgs Boson Discovery announcement by Peter Higgs – YouTube
Higgs boson update at CERN: July 4, 2012, press conference – YouTube
CERN Higgs Boson Discovery Seminar – YouTube
Latest update in the search for the Higgs boson (04 July 2012) – the slides

It was discovered at the Large Hadron Collider, currently the world’s biggest particle accelerator or atom smasher. It sends protons around and around at close to the speed of light in a vacuum and collides them with each other. Their kinetic energies are about 4000 times their masses, meaning a lot of energy that can go into making new particles, courtesy of E = mc^2.

The Higgs particles quickly decay into other particles, and it’s these particles that the CMS and ATLAS detector teams observe. The detector teams then reconstruct the masses of the the particles that produced the observed ones and look for mass values that they are likely to have. There are processes that can produce imitations of Higgs-particle decays, but they produce a continuous spectrum of masses. So the detector teams looked for bumps in graphs of reconstructed masses.

They found those bumps, at about 5 standard deviations above the background, and at the same mass, about 125 – 126 GeV, about 134 times more massive than a proton.

What’s next? Collecting more data, and trying to find out how closely this particle fits the expected properties of the Standard Model Higgs particle.

Finally, I agree with all those physicists who hate the label “God particle”.

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