Preliminary Higgs Results Are In (Was: Higgs Rumor Roundup)

I’ve changed the title since subsequent updates have morphed this into an entirely new post. Here is what I wrote yesterday:

CERN officials are of course being tight-lipped about the content of tomorrow’s announcement of the full combined CMS/Atlas dataset for 2011 (5.5 inverse femtobarns, corresponding to over 380 trillion proton collisions), but the rumor mill has been active. Here is what we can pretty safely expect:

  • No formal announcement of a Higgs boson discovery (at least not to 5 sigma of certainty).
  • Exclusion of the Higgs down to approximately 130 GeV.
  • Possible Higgs-like excess around 125 GeV (which is right in the sweet spot for SM predictions), but not to a high degree of certainty (3 sigma for Atlas, 2 sigma for CMS). More data will be needed to weed out background signal in this noisy region to determine whether this is a real signal or not.

Some excellent discussions may be found herehere, and here.

Update Dec.13:

And the results are in. As expected, slight excesses were seen, but nothing spectacular. More data will need to be collected to determine whether the excesses were a statistical fluke or not.

For more info about the hunt for the Higgs, including links to plenty of introductory background material, take a look at my previous post on the topic.
You’ll also note in the blog postings below numerous references to something called the “Look-Elsewhere Effect.” This is an important concept in the statistical analysis of data. Tommaso Dorigo has an excellent article about here.

ATLAS results indicate a weak (3.6 sigma) signal around 126 GeV. ATLAS data excludes Higgs from the regions including 114-115 GeV and 135 and up, leaving only the 115 to 131 GeV window.

CMS results are weaker, showing a small (2.4 sigma) signal at around 124 GeV. (Actually, CMS is seeing several tiny bumps.) Higgs is excluded in the range from 127 GeV to 600 GeV.

Official CERN press release is here. ATLAS conference notes here. CMS conference notes here.

Correction to the original posting above: No results of an analysis of the full combined dataset were announced. Analysis by each detector team (ATLAS and CMS) were done separately on their own datasets.

Some discussions of results from around the physics blogosphere:


About Glen Mark Martin

MCSE-Messaging. Exchange Administrator at the University of Texas at Austin. Unrepentant armchair physicist.
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2 Responses to Preliminary Higgs Results Are In (Was: Higgs Rumor Roundup)

  1. Pingback: LHC: “Evidence soon emerged however that this particular squib might be of the damp variety…” « Slugger O'Toole

  2. Pingback: Higgs: What’s In A Name? | Whiskey…Tango…Foxtrot?

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