Skip to the Main Content

Note:These pages make extensive use of the latest XHTML and CSS Standards. They ought to look great in any standards-compliant modern browser. Unfortunately, they will probably look horrible in older browsers, like Netscape 4.x and IE 4.x. Moreover, many posts use MathML, which is, currently only supported in Mozilla. My best suggestion (and you will thank me when surfing an ever-increasing number of sites on the web which have been crafted to use the new standards) is to upgrade to the latest version of your browser. If that's not possible, consider moving to the Standards-compliant and open-source Mozilla browser.

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

  • H→γγH \to \gamma\gamma
  • H→ZZ *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 ℓ +ℓ −\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 2ℓ2\ell (the standard H→WW *H\to W W^* search looks for opposite-sign di-leptons)
  • 3ℓ3\ell
  • 4ℓ4\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 December 20, 2011 5:04 PM

TrackBack URL for this Entry:   https://golem.ph.utexas.edu/cgi-bin/MT-3.0/dxy-tb.fcgi/2480



4 Comments & 0 Trackbacks

Re: Higg Non-News

First, I’m sorry to read your sister past away. That’s sad news. My condolences.

I’ve enjoyed your blog for many years now and I value your insight into physics, so I’m saddened to see you don’t blog as much as in the past. Your knowledge, technical topics, and attention to detail is rare it seems to me in the world of the web (or in general!), and while their are others who blog in a similar fashion, it’s not as many as I would like! But I think understand your decision, and I respect it.

I wonder, with the new year, is there a goal for your research? Is there a set of problems, or a problem, that is guiding your interest for the new year?

Take care,
mike

Posted by: mike on January 1, 2012 7:29 PM | Permalink | Reply to this

Re: Higg Non-News

My impression is that the discovery of the Higgs particle would be more of a triumph for the anti-multiverse school of thought than a triumph for the pro-multiverse school of thought - is this impression wrong?

Posted by: David Brown on February 26, 2012 7:51 AM | Permalink | Reply to this

Re: Higg Non-News

That is a complete nonsequitur.

Multiverse or no multiverse, it is almost guaranteed that the source of electroweak symmetry-breaking — whether a Higgs, or something more exotic — will be revealed at the LHC.

(I say “almost”, because there is a small probability that the Higgs is non-standard, and decays in a fashion that makes it very hard to detect at the LHC.)

Posted by: Jacques Distler on February 27, 2012 3:03 AM | Permalink | PGP Sig | Reply to this

Re: Higg Non-News

I have a bizarre theory of modified M-theory with the finite nature hypothesis; it seems to predict no Higgs mechanism, SUSY not as particles but as symmetry principles for Wolfram’s automaton, and total failure of the equivalence principle for VIRTUAL MASS-ENERGY but 100% success of the equivalence principle for real mass-energy. (The theory might be 100% wrong, but IT IS TESTABLE.)
See http://vixra.org/pdf/1202.0092v1.pdf “Finite Nature Hypothesis and Space Roar Profile Prediction”
The theory seems to explain the OPERA neutrino anomaly as a GPS timing problem due to slight deviations from the predictions of GRT.
See http://vixra.org/pdf/1203.0016v1.pdf “Anomalous Gravitational Acceleration and the OPERA Neutrino Anomaly (Updated)”.

Posted by: David Brown on March 5, 2012 2:04 PM | Permalink | Reply to this

Post a New Comment