Quantitative Measurements for the Higgs Boson

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Discussion Overview

The discussion centers on the quantitative measurements of the Higgs boson couplings to the W and Z fields as predicted by the Standard Model. Participants explore the current state of experimental data, particularly focusing on decay rates and the implications for the validity of the Standard Model in light of these measurements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the specific quantitative measurements that have been conducted to verify the Higgs boson couplings with the W and Z fields.
  • One participant mentions that the ATLAS experiment measures the Higgs decay to photon pairs at a rate 80% larger than the Standard Model prediction, while CMS also finds a similar trend.
  • Another participant notes that measurements from ATLAS and CMS are updated with new data and are available on ArXiv, emphasizing the importance of these sources for information.
  • A participant discusses the methodology for measuring Higgs couplings, explaining that the number of events is compared to expected values, and the consistency of these ratios is crucial.
  • There is a question about whether the only quantitative measurements available pertain to the Higgs diphoton rate, with some participants expressing skepticism about the conclusions drawn from this data.
  • One participant clarifies that the diphoton channel is currently the only one that might deviate from predictions, while other decay channels have shown agreement with the Standard Model.
  • A later reply raises the question of whether competing theories regarding the Higgs boson can be ruled out based on current measurements.

Areas of Agreement / Disagreement

Participants express uncertainty about the completeness of the quantitative measurements available and whether the current data sufficiently supports the Standard Model. There are competing views regarding the implications of the diphoton decay rate and the status of alternative theories.

Contextual Notes

Limitations include the potential for incomplete data or ongoing updates from experiments, as well as the dependence on specific decay channels and their interpretations. The discussion reflects a range of interpretations of the current experimental results.

QuantumSkippy
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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.
 
Physics news on Phys.org
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.
 
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.

QuantumSkippy said:
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?
 
MarekS said:
How do you make a non-quantitative measurement?
Find a peak without a reliable cross-section measurement.

QuantumSkippy said:
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.
 
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.
 
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.
 
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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