Quantitative Measurements for the Higgs Boson

QuantumSkippy

Hi everyone and happy New Year.

The Standard Model shows very specific and measurable couplings of the Higgs boson with the W and Z fields. What QUANTITATIVE measurements have been done to verify that these couplings are as predicted?

Thanks and looking forward to your replies. A lot of you guys would have supervisors at CERN or similar, and these couplings should be be known either to be measured or not measured at this stage.

Thanks.

Bill_K

Quote from the Resonaances blog:

The only glitch so far is the rate in which it [The Higgs] decays to photon pairs. Currently, the ATLAS experiment measures the value 80% larger than the standard model prediction, while CMS also finds it a bit too large, at least officially.

MarekS

These measurements are made by ATLAS and CMS and are updated as new data comes in. They are viewable free on ArXiv. Particle physics blogs are also a source of good information.

Quote by QuantumSkippy

The Standard Model shows very specific and measurable couplings of the Higgs boson with the W and Z fields. What QUANTITATIVE measurements have been done to verify that these couplings are as predicted?
Thanks.

How do you make a non-quantitative measurement?

mfb

Quote by MarekS

How do you make a non-quantitative measurement?

Find a peak without a reliable cross-section measurement.

Quote by QuantumSkippy

What QUANTITATIVE measurements have been done to verify that these couplings are as predicted?

The measured number of events (in the SM) are compared with the expected number, the ratio should be consistent with 1 - and it is, in all studied channels (see arXiv for publications).
In addition, the production mechanisms depend on the coupling to W and Z, therefore you can check the ratio of production channels as well. I don't remember to see such a study (at least not public - the publications often add several subchannels to a few data points), this might need more data.

QuantumSkippy

Thanks very much for the replies. Does this mean that the only quantitative measurements of the couplings of the Higgs to the W and Z fields are those on the Higgs diphoton rate? If that is the case, it sounds like they are jumping the gun a bit. Is that the case?

Secondly, is there somewhere published or on the web where they list the criteria that they have verified, which lend support to the conclusion that it is the Higgs?

Thanks very much for your replies and looking forward to further replies.

Cheers.

Bill_K

Does this mean that the only quantitative measurements of the couplings of the Higgs to the W and Z fields are those on the Higgs diphoton rate?

No, it's just that that channel is the only one so far that might be different from the standard model prediction. If you look further down on the Resonaances blog, they have a plot from ATLAS showing how well the other decay channels H → bb, ττ, WW and ZZ agree with predictions.

QuantumSkippy

Just had a look at the Resonaances Blog which Bill_K very kindly supplied, and this answers most of my questions. Thanks heaps! It certainly is looking like the standard model Higgs.

Can competing theories which dish up a Higgs boson with certain variations be ruled out at this stage?

Cheers and thanks for your answers.

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QuantumSkippy	Just had a look at the Resonaances Blog which Bill_K very kindly supplied, and this answers most of my questions. Thanks heaps! It certainly is looking like the standard model Higgs. Can competing theories which dish up a Higgs boson with certain variations be ruled out at this stage? Cheers and thanks for your answers.