News from CERN

Very light posting recently, partly due to being busy keeping up with my class, but more due to just not noticing anything particularly newsworthy. Matt and Lubos have quite a lot to say about Time magazine’s not describing the Higgs mechanism accurately, but I find it hard to get too excited about that, with my sympathies lying with any poor journalist given the impossible task of explaining this in a few words to the public.

Today at CERN there’s an LHCC meeting, with status reports on the machine and the experiments available here. The 8 TeV proton-proton physics run has just about ended, with the next week or so to be devoted not to luminosity production, but to machine studies. The integrated luminosity for the run will be about 23 inverse femtobarns, significantly above the original plan for the year. A heavy-ion run will end in February, after which the machine will be shut down for a long period in order to fix the magnet interconnects and other problems, to allow running at or close to the design energy of 7 TeV/beam. The current plan has proton-proton physics at 6.5 TeV/beam starting again about April 2015.

It seems likely that there will be no new results about the Higgs until the Moriond conference in March. CMS and ATLAS will then have quite a while to work on doing the best possible analysis of their 7 and 8 TeV data for information about the Higgs. From now on, attention will focus on what CMS and ATLAS have to say about the signal sizes in the various channels where the Higgs is supposed to show up, as well as theoretical studies of how possible next generation accelerators would perform in terms of doing better at these measurements than the LHC. The LHC Higgs Cross Section working group is meeting today and tomorrow on this topic, talks are available here. Next week the KITP will host a similar workshop.

The continuing big story from the LHC is that of no SUSY or other BSM physics showing up. The LHCC ATLAS slides have

Physics beyond the SM did not show up yet. There is no need for preliminary conclusions. Let’s continue our work and look were we haven’t looked so far.

but theorists are definitely starting to draw preliminary conclusions, needed or not. At Scientific American, Glenn Starkman has a piece entitled At CERN: Down in the Mouth in Paradise which paints a sorry picture of the situation caused by SUSY not showing herself:

The Standard Model is absurdly fine-tuned, we were told – balanced on a knife-edge off which it has no right not to tumble. It has an un-natural hierarchy of scales. It has too many free parameters, and some of them are very, very small. Why, the electron mass is less than 0.00001 times the weak scale (the energy scale governing weak interactions such as the W and Z boson masses), which is itself 10-17 (that 0.0000000000000001) times the Planck scale (the energy scale governing gravity)! And speaking of gravity, the Standard Model can’t accommodate quantum gravity. We need Low-Energy Supersymmetry, or Technicolor, or Large Extra Dimensions, or … One of these MUST be found at the LHC!

Forty years of theoretical work has been based on these expectations. Papers with thousands of citations have been written. Courses taught. Textbooks published.

Prizes awarded! Illustrious careers navigated! And yet despite all this build up of theoretical expectations, there is no experimental hint of anything outside the Standard Model at the LHC. Hence the long faces and worried words wherever theorists gather to drink coffee. Hence the disappointment in the eyes of the young experimentalists looking forward to the next accelerator, the next frontier where their mark will be made…

Walk the halls, go to theory seminars, have lunch with a theorist, or an ambitious young experimentalist. Look for the classic symptoms of grief.

Denial. Vigorous debates about whether the fact that the dog did not bark in the night suggests that it is a Chihuahua or a Rottweiler. My friends – at some point if there is no barking, we must conclude there is no dog.

Anger. At those of us “misguided” enough to doubt the imminence or even the necessity of Beyond the Standard Model physics.

Bargaining. Perhaps BSM physics has not been discovered because we’ve been demanding too much explanatory power from science. If we just relax our expectations for the predictivity of science, and introduce a multitude of universes in which we occupy a particular one best suited to our existence, then we can let our extensions to the Standard Model be un-natural, many of their properties unpredictable, and explain why they haven’t been discovered yet!


We’re not ready for Acceptance! At least, sitting here listening to the LHC hum, I can still hope.

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9 Responses to News from CERN

  1. Nick M. says:

    And so the “nightmare” begins!

  2. cormac says:

    …’At some point we must conclude there is no dog?’
    Oh please. At what point exactly?
    Ruling things out is a very long and laborious process, not helped by commentators anxious to jump the gun. The history of particle physics is littered with examples of phenomena that took many many years to show up, many of which are now taken for granted.
    Glenn Starkmann needs to remember that it took decades to find the atom, decades to find the neutrino and decades to find the Higgs….what exactly were you expecting?

  3. Shantanu says:

    cormac, by this logic we should continue to design experiments designed to look
    for magnetic monopoles (and so on).

  4. Thomas Larsson says:

    It has taken decades to not find susy.

  5. Jose Ignacio says:

    There is a great experimental evidence that there is physics beyond the standard model: dark matter. The standard model is unable to explain the 80% of the matter of the universe.

  6. Simon says:

    There are very good reasons to look for magnetic monopoles.

  7. srp says:

    From the SciAm post:

    “Fifty-one years after its basis was explored by Sheldon Glashow, forty-five years after the full theory was proposed by Steven Weinberg (and independently the next year by Abdus Salam), the Standard Model has successfully accounted for or predicted all calculationally tractable experimental results in particle physics. ”

    Note the loophole there.

  8. emile says:

    Let’s wait just a few more years before getting too depressed. Once the LHC has run for a few years at full energy, and that the Higgs couplings are still consistent with the SM, that no signs of BSM physics has appeared, we’ll know we are living with the nightmare scenario. In the meantime, other experiments could turn up surprises.

  9. Shantanu says:

    at the risk of repeating what’s been said many times, there is absolutely NO evidence
    from astrophysical data alone, that dark matter has anything to do with SUSY or weak interactions or physics beyond standard model.
    It could very well be an axion or primordial black hole or a massive graviton.
    The WIMP miracle argument has been oversold and in its simplest version is already ruled.

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