Today’s Higgs Results

The discussion after the talks is going on at CERN now, and the results that were presented agree well with what was posted here over the past week or so. This looks a lot like a Higgs near 125 GeV. Hiccups in the streaming make it difficult to impossible to follow the discussion. Caught Heuer at the end urging caution: “intriguing hints”. This looks to me like a lot more than “intriguing hints”: it’s about what you would expect if a Higgs was there at 125 GeV, highly unlikely to see if there is no Higgs there.

The ATLAS results are here

Higgs to gamma gamma: 2.8 sigma bump at 126 GeV

Higgs to ZZ to 4l: 2.1 sigma (3 events near 125 GeV)

Higgs to WW to l nu l nu: Data not fully analyzed, 1.4 sigma excess at 126 GeV

Combination: 3.6 sigma excess at 126 GeV.

The CMS results are here


Higgs to gamma gamma
: 2.34 sigma bump at 123.5 GeV.

Higgs to ZZ to 4l: 2 events seen near 126 GeV (expect .5 background)

Combination: 2.4 sigma excess at 124 GeV.

I see Tommaso Dorigo is posting a detailed analysis here under the title “Firm Evidence of a Higgs Boson at Last!”. He’s likely to be the best source around for a discussion of the details.

Update: Go to the blog of Philip Gibbs now to take a look at his (highly unofficial) plots of the combined ATLAS+CMS+Tevatron results on the Higgs. You might also want to check out Matt Strassler’s blog entry about this, which wins the award for being downbeat (“Inconclusive, As Expected”). For some reason he is incensed by Tommaso Dorigo’s “Firm Evidence”.

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71 Responses to Today’s Higgs Results

  1. Anonyrat says:

    Brian Greene has an op-ed in the New York Times about the Higgs.
    http://www.nytimes.com/2011/12/15/opinion/waiting-for-the-higgs-particle.html

  2. tulpoeid says:

    ‘ ‘ I think “inconclusive, as expected” would have been a good headline for this past summer’s Higgs results. The latest results deserve something different and better. ‘ ‘

    Why?

    They are (i) not perfectly understood yet, and they are (ii) consistent with both assumptions. Moreover, this was expected and well calclulated given the current integrated luminosity.
    Also, have you said the same about all previous 3-sigma hep results? Would you mind writing a post with the history of all 3-sigma results past?
    God, I’m really glad cern people are proving to be better than the crowd commenting on blogs these days and they are staying unaffected for the biggest part (the management might not be the best example of what I’m talking about at the moment). I think you are exhibiting a very uncharacteristic case of string-theorist-like way of thinking during this last week.

  3. Paolo Valtancoli says:

    In my opinion the standard model is valid up the grand unification scale! In any case since the four colour theorem proved to be useful to derive the right Higgs mass, one should extract all its consequences for the MSSM model…

  4. Bernhard says:

    tulpoeid,

    the CERN people, here and include both analysis leaders + teams are very excited about this. See http://www.nature.com/news/live-qa-the-hunt-for-the-higgs-1.9642

    Murray says: ” We have no proof, but I polled 10 tof the leaders of the ATLAS search and my wife last night if they thought we had found it and they ALL said yes. But that is not proof, it could be over-excitement.”

    Got the picture? Nobody is claiming a discovery but the feeling of optimism among the experimental folks that this result will hold up is very high. They might be wrong and acknowledge that, but “inconclusive as expected” does not even begin to draw the correct picture of what people REALLY THINK about this result. That Strassler wants to be cautious that’s fine, but again what a downbeat title.

  5. vmarko says:

    I remember seeing the CMS result in the H->4l channel to have observed 13 events, as opposed to the expected 9.5 at that peak. Is there any clear data published about the total count of excess events observed by CMS and ATLAS?

    I mean, the luminosity of 5 inverse fb basically means they have produced 10^{14} or so collisions (essentially a very large number). Out of all that, they have filtered out only a dozen of events, and found 13 instead of expected 9 (in that channel). I guess that the total number of events (all channels summed) does not go above 100 or so. How much can you trust the statistics of that?

    I could flip a coin 20 times, and get 13 tails plus 7 heads, instead of 10 plus 10. Does that mean that I am seeing some real signal about the coin fairness?

    I believe that people could have a better intuition about how much to trust that 3.5 sigma result, if they knew the actual number of observed events, rather than looking at a fancy graph with a “peak that goes above the green and yellow strips”. Is this data available anywhere on the net in a clear easy-to-read form?

    Best, :-)
    Marko

  6. Peter Woit says:

    Marko,

    You’re just talking about 1 channel and 1 experiment. The interesting thing here is that there are 3 channels/experiment, no one giving much of a signal on its own, but they are all showing something. In the ZZ -> 4l channel, what’s important is that you’re seeing several events close to 125 GeV, with expected background at that energy very low.

  7. anonyrat says:

    Sorry, looks like comments on the old thread are closed, so posting it here. Part II of Norman Dombey’s series on Abdus Salam is on arxiv.org.
    http://arxiv.org/abs/1112.2266
    “Abdus Salam: A Reappraisal. Part II Salam’s Part in the Pakistani Nuclear Weapon Programme”

    Abstract: Salam’s biographies claim that he was opposed to Pakistan’s nuclear weapon programme. This is somewhat strange given that he was the senior Science Advisor to the Pakistan government for at least some of the period between 1972 when the programme was initiated and 1998 when a successful nuclear weapon test was carried out. I look at the evidence for his participation in the programme.

  8. Peter Woit says:

    I realized I didn’t respond to the question about numbers of events. Look at the CMS and ATLAS papers for each channel. For ZZ -> 4l they plot number of events vs energy, with the number of events in each bin 0, 1, or 2, expecting to see o in each bin. For gamma-gamma, they also give a plot of number of events vs energy, here the numbers in each bin are large (several 100/ GeV) and what you are looking for is a bump in the distribution.

  9. Bernhard says:

    Outrageous hype from M. Kaku at the Wall Street Journal:

    “So far, one of the leading candidates to explain dark matter is string theory, which claims that all the subatomic particles of the Standard Model are just vibrations of a tiny string, or rubber band. ”

    http://online.wsj.com/article/SB10001424052970204026804577098382660789136.html

    Apparently, Kaku already made a complete symbiosis of SUSY with string theory.

  10. Anand says:

    Looks like they will find the “Higgs.

    Let the politics Nobel begin – by all three groups. First opportunity will be this weekend for Englert to work Nobel Committee member Lars Brink. Past performances were great on this topic.

    http://cgc.physics.miami.edu/Miami2011.html

  11. Z says:

    If the Higgs is going to be confirmed, this is also good opportunity for the Nobel Foundation to change the archaic rules limiting the prize to three people before next year’s prize. Even on the theory side, more than three people (including Peter Higgs) deserve the prize.

    Perhaps, if selecting between an arbitrary number of people is too distasteful, awkward, or against the constitution/charter, the committee could also simply give the prize to the “CMS Collaboration” and the “Atlas Collaboration”, letting those groups decide on how to split the prize money inside them. If corporations being people is good enough for the Supreme Court of the US, surely a scientific collaboration is a good enough person?

  12. simona says:

    Figures 1 and 2 in the ATLAS note show even a greater excess at ~102 GeV; however this mass range is left out in the statistical analysis in Figures 7 and 8 where the range begins at 110GeV. Any ideas on that?

  13. Peter Woit says:

    simona,

    I don’t know, but there likely is some innocuous reason, known to the ATLAS people. It’s also possible they don’t know, but figuring it out has been a relatively low priority. Whatever it is, LEP has ruled out the possibility that it’s the Higgs, so ignoring it in these notes makes sense. The results presented this week in any case aren’t the final analysis of this data, but whatever they could get done by the deadline of being ready to present on this date.

  14. Chris Austin says:

    LEP excluded the Standard Model Higgs below 114 GeV, but apparently more complicated Higgs sectors can still have some Higgs bosons with mass below 114 GeV, and be consistent with LEP. See for example 0811.3537.

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  16. Chris Austin says:

    Jester wrote a great post on how a lighter Higgs could have escaped discovery at LEP.

    The fact that ATLAS don’t discuss the narrow excess at about 101 GeV in Figs 1, 2, and 5 (top right) of their Dec 11 note might simply be because the title is, “Search for the Standard Model Higgs boson”. Although if you allow for the slightly shorter error bars at around 126 GeV, and that the excess there is in 2 neighbouring data points, the excess at about 126 GeV is perhaps a bit bigger than that at about 101 GeV.

  17. pah says:

    Chris Austin,

    I see only a single-bin fluctuation, totally insignificant. It’s debatable if there’s a significant excess at 125 GeV, but what you’re seeing at 101 GeV is nothing.

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  19. Chris Austin says:

    In my second comment I should have said “more significant” rather than “bigger”. I agree that the excess at 101 GeV is not significant.

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  21. Ric - ½ g tr(Ric) = 8πT says:

    I think, after this is settled a discovery, we should focus on why the mass is so close to the half of the VEV (246 GeV). My thoughts is that the coupling constant is as that, yet anomalies and RG corrections drive it up to ~125 GeV.

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