13 December 2011

We wish you a merry Higgsmass - perhaps?

In a seminar held at CERN today, the ATLAS and CMS experiments presented the status of their searches for the Standard Model Higgs boson based on considerably more data than those presented at the summer conferences.

ATLAS search for HiggsThese are sufficient to make significant progress in the search for the Higgs boson, but not enough to make any conclusive  statement on the  existence or non-existence of the elusive Higgs.

The main conclusion is that the Standard Model Higgs boson, if it exists, is most likely to have a mass constrained to the range 116-127 GeV. In this mass range both ATLAS and CMS have an excess of candidates for Higgs boson decays exceeding the expected background by about "two sigma". This excess has in each experiment a probability of about 1% to be due to a random upwards fluctuation in the background.

Furthermore, the maximum probability for a possible Higgs boson mass is found to be 126 GeV in ATLAS and 124 GeV in CMS, a difference which is within the experimental mass resolution.

While the results are still too weak to claim a discovery, and still preliminary, you would probably have a hard time finding a bookmaker betting against a Higgs boson at a mass around 125 GeV.