Higgs Update

Updated results about the Higgs are being reported at Moriond today, slides available here. The organizers have given the talks titles with “BEH Boson” replacing the usual “Higgs Boson” (to promote Englert’s shot at a Nobel), but the speakers have mostly ignored this, titling their slides with the usual “Higgs” or maybe “Standard Model Scalar”. Some more details are starting to appear at the CMS site here, presumably ATLAS will soon update their site here.

The only surprise so far is that the CMS results for the gamma-gamma channel are not ready yet. Philip Gibbs has very good coverage of the latest news here, including this about CMS:

Rumour puts the CMS diphoton excess at 1.0 +- 0.2, to be shown at Moriond QCD next week perhaps.

As mentioned here a couple weeks ago, the size of the ATLAS excess in that channel has gone down since last year, now at 1.65 +/- 0.24(stat) +/- 0.21(syst) (where 1.0 is the SM prediction). If you believe Philip’s rumor, the combined ATLAS + CMS result for the gamma-gamma channel would be 1.32, consistent with the SM prediction at the level of 1-2 sigma.

In the ZZ channel, CMS reports a cross-section relative to SM of .91 +/- 0.27, ATLAS 1.7 +/- 0.5. Combining them gives 1.30, again quite consistent with the SM. For the WW channel, CMS has .76 +/- 0.21, ATLAS 1.5 +/- .6, averaging out to 1.13, again very much consistent with the SM. For channels with bottom quarks, CMS has 1.3 +/- .6 and for channels with taus CMS has 1.1 +/-.4, ATLAS says the expected signal is still to small in these channels for them to say much.

Some more talks this afternoon may give a bit more detail.

All in all, the story is that this is looking very much like a garden variety SM Higgs, which is discouraging for hopes of hints about how to get beyond the Standard Model. The experiments will continue working on improving their analyses of this data, but it seems unlikely that the picture will change much. There’s going to be a long drought now until we see significantly better data for these numbers. Probably not until 2016 until the LHC has been operating long enough to produce significant luminosity at higher energy.

The New York Times yesterday put out a wonderful special issue of its Science Times section, devoted to an excellent long article by Dennis Overbye telling the story of the Higgs discovery from the point of view of the ATLAS and CMS scientists (and emphasizing their rivalry). Highly recommended reading. The article does credit a certain blog with being the venue where a mistaken early Higgs claim was leaked (I’m sorry to hear that that ruined some people’s vacations), although the fact the the actual Higgs discovery news broke somewhere else than in the Times doesn’t get mentioned…

Professor Matt Strassler has a posting about the Times article, explaining how it shows that other particle physics bloggers were wrong to think that the 3 sigma signals reported by ATLAS and CMS back in late 2011 were strong evidence that the Higgs had been found, and that he had been right to be skeptical.

Update: New ATLAS results are here. Do not miss the extremely cool animated gifs of the evolution of the Higgs signal as data accumulated.

Update
: Valuable commentary at Resonaances.

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11 Responses to Higgs Update

  1. john McAllison says:

    “There’s going to be a long drought now until we see significantly better data for these numbers”

    Tut tut, Peter, you’re so ungrateful that it’s 2013 with probably the greatest discovery of the past few decades in the bag. I’m sure the 25\fb of data will keep people busy for the next two years. If anything, they must be ecstatic they have this amount of data compared to 2011 when they were hoping for 1\fb over the year.

  2. Peter Woit says:

    John McAllison,

    The drought comment was just about these very specific Higgs branching ratio numbers, which I think it is going to be hard to dramatically improve on without a lot more data. There are many, many other things to look for in the LHC data which I’m sure will keep people quite busy, and hopefully will turn up something unexpected.

  3. King Ray says:

    Peter,

    Thanks very much for the link to the NYT Higgs piece. I liked the analogy of the Higgs field to snow, with massless particles flying above it like birds (see the Higgs drawings by Nigel Holmes).

    I thought the ending of the article was pretty neat; Prof. Higgs has a good sense of humor:

    When she showed the Atlas 5-sigma result, the audience exploded again. The applause seemed to go on forever. It had been left to Dr. Heuer to declare officially that a new particle had been discovered.

    “I think we have it,” he said. The cheers began again. Dr. Higgs was seen wiping away tears.

    The morning dissolved into pandemonium and Champagne, in the CERN auditorium and in labs, classrooms, conference rooms and living rooms in every time zone in which humans wondered about their universe. Dr. Wu waded through the crowd. She hugged Dr. Higgs.

    “I’ve been looking for you my whole life,” she said.

    “Well,” he replied, “now you have found me.”

  4. Nick M. says:

    Hi Peter,

    The link that you have given for the “slides available here” section of your post — that is, the first link — seems to have a ‘security certificate error’ as reported by the three different browsers that I used to try to go there; i.e., IE, Firefox, and Chrome. I decided to throw caution to the wind and go all the way there anyway, and indeed they are the slide portion of the presentations at Moriond in PDF format. I think that they may be the slides that accompany these WebCasts as given at Moriond today on the Higgs.

    By the way, Thanks for compiling this Higgs update,
    – Nick

  5. Pingback: Nightmare scenario, aggiornamenti da Moriond | oh tempo le tue piramidi

  6. Nick M. says:

    Peter,

    Sorry for all the worry about ‘certificate error’, as the certificate issuer for this site, the French based CNRS2-Standard, seems to not be well recognized by the current crop of U.S. based browsers. Anyway, there doesn’t seem to be any real security rick involved with this site, despite all the browser warning hullabaloo.

    – Nick

  7. Shantanu says:

    Peter and others,
    pre-snowmass meeting going on at slac.
    You can listen to the audio of the cosmic frontiers part of it.

  8. Peter Woit says:

    Shantanu is referring to this ongoing workshop which looks like it includes quite a few interesting talks:
    https://indico.fnal.gov/conferenceDisplay.py?ovw=True&confId=6199

  9. Nick M. says:

    Peter,

    New Scientist just released the article “Rumour points to a completely boring Higgs boson” where they quote ‘yours truly’ just after the section heading “Garden variety”.

    – Nick

  10. Peter Woit says:

    Nick M.,

    Thanks. Good to see that someone else is being quoted as the source of rumors this time, not me…

  11. chiz says:

    Meanwhile AP are reporting that if the particle isn’t a Higgs then there is only one other thing it could be – a graviton. Cool. Gravity is now a short range force. That will be a boon to the space-launch people. I better go and nail everything down.

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