Of Particular Significance

Update July 26th

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 07/26/2011

Correction below — a couple of readers pointed out that I had read a misquote of what Rolf Heuer, director general of CERN, had actually said.  I’ve updated the post to reflect what he said and why he said it, though the main point of the post doesn’t change at all.

I’ve left the EuroPhysics conference … With 400 talks, and a hundred or so from the Tevatron and the Large Hadron Collider, it was information overload.

There are two more days of summary talks at the conference, and tomorrow (Wednesday) afternoon there will be a bit more on the Higgs particle search.  A combination of the DZero and CDF Tevatron results will be presented, and perhaps a preliminary combination of the ATLAS and CMS results at LHC.  [I won’t be there, so don’t look for the update as it happens…]  The combinations can be done roughly in your head by looking at the various experiments separately, so there should be no surprises.

The one thing I want to remind you, in case the press makes a big deal out of what is said on Wednesday, is that what has been done so far to obtain a hint of a Higgs signal involves a very difficult measurement.   [Soon I’ll write an explanation of what I mean by this, but for now you can read more about this here. ]  The experimentalists are well aware of that, and say so both in public and in private.   I believe I saw the director general of the CERN laboratory quoted as saying this will all be cleared up by the end of the year.  UPDATE: This was indeed what I saw, but what I saw was itself a misquote; Heuer actually said “it” will be cleared up by the end of next year.   Either statement is true, depending on what “it” is.

  • If “it” means finding or excluding the Standard Model Higgs particle (remember that’s not the most general Higgs particle, see the Higgs FAQ) then that may not be fully settled until late next year — though in saying “end of next year” Heuer is being suitably conservative.
  • If “it” means figuring out if the current hint of a Higgs particle signal is a mirage or something real, that is probably something that will start to be settled between this December and next June.

Either way, [and here we return to the original post]  notice what this also implies: this [meaning the current hints] will not be cleared up much before the end of the year.  Science requires patient work, especially when the methods are challenging and fraught with subtleties.

I myself am spending today at the Large Hadron Collider, consulting with numerous experimental colleagues.  There are so many issues for us all to think about, especially in making sure that no stones are left unturned in the search for new phenomena.  Currently the number of unturned stones is still very, very large.  [Just finished a paper with three colleagues pointing out a whole pile of them.]

Meanwhile, please take a look at the new Higgs Frequently Asked Questions page version 1.0 if you are interested.  Comments/questions welcome!  Other things coming soon: Some introductory remarks on particle physics, why we do it and how it is done; more interpretation for non-experts on what we learned at the EuroPhysics conferences; and the third and final video clip from my public talk in March.

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3 Responses

  1. I saw the press conference and the DG said that the question of existence of the Higgs boson would be settled at the end of next year. Some people thought he had said end of this year but he certainly said next year. I have checked a recording 🙂

    1. Oh, I thought that DG was David Gross. If DG stands for what I think it stands for now, then you should better *not* try to interpret the words.


      The original newer plan to run through the end of 2012 was designed exactly in such a way that if the SM is right, either exclusion or discovery would be pretty much guaranteed by the end of the run in 2012, with around 15/fb or more.

      For a quick graph of the significance after a few inverse femtobarns for different Higgs masses, see


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