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December 20, 2011

Higg Non-News

I missed the brouhaha surrounding the LHC Joint Higgs Search Progress Report. But, luckily, there’s still something contentful to add to what’s already been said.

Both groups (ATLAS and CMS) found statistically-significant excesses in two channels, corresponding to

  • HγγH \to \gamma\gamma
  • HZZ *H\to Z Z^*

with an invariant mass centered around 125 GeV.

The latter decay mode yields a 4-lepton final state where one of the + \ell^+\ell^- pairs has an invariant mass of 91 Gev, corresponding to the decay of an on-shell ZZ (the other ZZ is, necessarily, off-shell). Since the relevant 4-lepton final states have relatively low backgrounds, the experimentalists could have (modestly) improved their results by relaxing their constraint that one of the ZZs be on-shell. My colleague, Can Kiliç, and collaborators have a recent paper advocating exactly such an analysis.

According to Can, this wouldn’t quite have boosted CERN into 5σ5\sigma discovery-territory, but it would have made the result more compelling (or, conversely, less-so, depending on the result).

In fact, Can and co. go a little further, and advocate looking in a number of multi-lepton channels:

  • same-sign 22\ell (the standard HWW *H\to W W^* search looks for opposite-sign di-leptons)
  • 33\ell
  • 44\ell

with varying amounts of MET. Of course, nothing substitutes for greater integrated luminosity, which is what 2012 is all about.

Posted by distler at 5:04 PM | Permalink | Followups (4)

December 19, 2011

Vivian Distler 1965-2011

Vivian Distler, in Dec 2009

More here, here and, yes, here.

Posted by distler at 4:55 PM | Permalink | Followups (8)