Higgs At Last!

The event has taken place. CMS observes a Higgs candidate. Adding up all channels except for tau decays, they see 5.1 sigma. Adding in the tau channel (where there has been a lack of the rare event) drops it to 4.9 sigma. The big news is from ATLAS, which is seeing a Higgs-like signal at 5.0 sigma confidence. After 48 years, the Higgs boson has at long last been discovered! Phil Plait has a nice summary. A more detailed blow-by-blow account can be found in Sean Carroll’s live blog of the event. Aidan Randle-Conde also did a live blog over at Quantum Diaries. Prof. Matt Strassler has published his take. The most concise summary ever can be seen here.

By and large, everything seems consistent with the Standard Model Higgs, although there are some deviations in the branching ratios. These could mean either new physics or merely that more data needs to be collected to smooth out statistical fluctuations in some of the rarer decay channels.

It was nice to see Englert, Higgs, Guralnik, and Hagen sitting in the front row. Kibble couldn’t make it, and Brout passed away last year.  These were the theorists who came up with the Higgs mechanism.

And here are the official press releases:

• CERN Press Release
• Observation of a New Particle with a Mass of 125 GeV | CMS Experiment
• ATLAS Experiment