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Where is the Higgs Hiding? March 12, 2008

Posted by gordonwatts in Higgs, physics.

Yesterday, at the Moriond QCD conference, Uli Heintz gave the Tevatron Top Mass talk (pdf). New mass results have made the Higgs a little less mysterious. Summer results had a measured top mass of 171.3+-1.7 GeV and now it is 172.8 +- 1.4 GeV. This is good news for the Standard Model.

One of the beauties of the Standard Model is that it holds together so well as a theory. It predicts many different experimental measurements. And all those measurements must be in line with each other — the model cannot accommodate a measurement that is out of whack. And the better we make these measurements the better we can tell when one is out of whack.

The Higgs mass is no different. Even though we’ve not seen it yet, the Standard Model predicts its mass. With the new top mass result, the predicted mass is 87 +36-27 GeV. Using last summer’s top mass the predicted Higgs mass was 76 +33-24 GeV. Note the very large errors on those numbers – there is a lot of slop in that measurement!

This is good for the Standard Model because of work done at the LEP collider. They searched for the Higgs and didn’t see it – they know that the Higgs mass is more than 114 GeV. The summer’s prediction put the Standard Model more out of whack than the current one – the new predicted value of the top mass is more in line with the LEP Higgs search.

Still – I’d love to know where that thing is hiding (along with everyone else)! The latest Higgs results should have been released – but I’ve not seen them publicly posted yet.

N.B. That plot is the summer plot — I couldn’t find the plot with the most recent results – I found it only in Uli’s talk.



1. Philipp - March 12, 2008

Well, it’s true that the Standard Model holds well together as a theory, but only in the ‘medium’ energy range. In the extremes energy ranges the theory fails (e.g., Neutrino mass). Also it seems not to explain the basic values like masses, speed of light . But it’s just the question: which model/theory is better…

Mr. Watts, could you maybe shortly describe the (most probable) decay channels for the Higgs?
Thanks in advance!

2. Dave Bacon - March 12, 2008

“The Higgs mass is no different. Even though we’ve not seen it yet, the Standard Model predicts its mess. ”

Typo alert! (And a funny one to boot 🙂 )

3. Gordon Watts - March 12, 2008

Wow – multiple typo-s. That title wasn’t even english!

Philipp – things like masses, etc., are input parameters to the SM. You could say that it is broken because it doesn’t predict it – but that isn’t the reason we normally call it broken.

The most probably decay channels depend on the mass the Higgs is. If it is low mass, which is a good guess, it will decay to botom quarks, a pair.

4. Alejandro Rivero - March 13, 2008

With the massive neutrinos, perhaps we are barking at the wrong treee, and we need to ask where is the Majorana mass hidden.

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