Moriond 2012: Uncertain signals from the Higgs boson

Tevatron’s experiments presented the refined measurement of the mass of the W boson announced 2 March. This allowed a refined indirect measurement of the Higgs mass to be presented: mH = 94 +29-24 GeV. “The W mass plays an important role in determining the consistency of the Standard Model,” said Rafael Lopes de Sá, from Stony Brook University. In other words, even after the Higgs is measured, it will have to correlate with the mass of the W in order to fit with the Standard Model.

This talk was followed by reports on the most recent analyses of the Higgs searches by the CMS and ATLAS experiments that use the complete 2011 data sets. CMS is now analysing data across 11 channels and ATLAS across 12 channels; some were presented for the first time yesterday. Both experiments showed an excess of events compatible with a Standard Model Higgs in, for example, H → γγ: at 126.5 GeV (2.9σ)* in ATLAS, and at 125 GeV (2.9σ)* in CMS. These results are compatible with the range presented by Tevatron’s experiments.

However, as pointed out in Guido Altarelli’s presentation, some issues remain to be clarified. For example, three H→ ZZ→ 4l CMS events gave a mass measurement at 119.5 GeV (2.5σ)*. Also, ATLAS does not observe an excess of events in the WW channel while CMS data is compatible with such an excess.

Further studies are clearly needed, and the whole community is looking forward to the 2012 LHC run planned to begin this week.

(*) All the σ are calculated locally. They refer to analyses that do not include the “Look Elsewhere” effect.

You can access all the Moriond QCD presentations here.