New LHC Physics Phase Begins!

cern-first-physicsWell, here we go. It has been a little over 20 years since I’ve been actively working in this field and have been hearing about the promise of this machine, the Large Hadron Collider (LHC), and now it is really here, working, and colliding protons at an energy much higher than any previous experiment, promising us to a glimpse of new aspects of how the universe works. It is not guaranteed, of course, but there’s a great deal of hope, and so much of what we know strongly suggests that there’s going to be some exciting things to learn. See the list of related posts below for several bits of background on the LHC, or go to CERN’s website. [Image above right -click for larger view- is a CERN-supplied montage of data/images from the various experiments at the LHC. Caption: 7 TeV collision events seen today by the LHC’s four major experiments (clockwise from top-left: ALICE, ATLAS, CMS, LHCb).]

Two of the things foremost in people’s minds are on one hand the Higgs (the particle or particles that ultimately give masses to the elementary particles that make up the matter we know and love) – this is what the machine was principally designed to study, and on the other hand the possibility that we will find a candidate particle that will be the principal component of the matter in the universe that we don’t know (which happens to be about 83% of all matter). Finding a dark matter candidate would be a truly remarkable discovery, and may well point to all sorts of new physics. Those of us studying things like string theory hope that such new physics might be “supersymmetry”, a new symmetry of nature that relates two large classes of particles and implies the existence of entire families of particles we’ve yet to discover (said dark matter candidate would be the first of them). Supersymmetry does not imply string theory, but since string theories rather like it (and are the theoretical physics context in which it was first uncovered – the simplest string theories require it for their internal consistency), finding it would give us some further experimental encouragement (beyond the non-particle physics contexts that I’ve discussed recently) that we’re doing something that nature may well care about.

A third thing on people’s minds is, of course… the unexpected. The LHC may show that there may be exciting physics out there that we really had not anticipated, and we have to set aside our notebooks, turn to a blank page and start again. That may be the most exciting of possibilities (depending upon who you talk to, things like extra dimensions and mini-black holes may or may not be on that list of “unexpected”), as we’d have a lot of fresh thinking to do.

Anyway, first things first. Let’s celebrate that the LHC is on the hunt for real, and wait for what unfolds over the coming years (yes, years, probably). Have a look at CERN’s announcement here for some of the news.

-cvj

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7 Responses to New LHC Physics Phase Begins!

  1. Nige Cook says:

    I’m also excited about it, although not so much about the prospects of finding SUSY 🙂 The electroweak theory is correct in its existing tested predictions, but it will be interesting to see what the electroweak symmetry breaking mechanism really is.

    Nobody has seen a Higgs boson, needed to produce the broken symmetry in which standard model. What if the electroweak symmetry is broken at all energies, i.e. is not unified at high energy by the disappearance of mass for the W and Z bosons at such high energies when the speed of such bosons is supposed to reduce interactions with the Higgs field? The electroweak theory has only been confirmed for the massive W and Z boson case, ie low energy. Mass need not be provided by the complicated symmetry breaking Higgs field. If Higgs is fiction, the W and Z bosons may be massive at all energies, with no electroweak unification occurring at high energy. Weinberg et al only achieved solid electroweak unification by mixing the electromagnetic and weak gauge bosons with his ad hoc mixing angle at low energy; this isn’t so impressive because simply it doesn’t prove unification occurs at high energy.

    I’d like to predict that far from telling anything about SUSY, the LHC is not even going to deliver a Higgs boson. However, maybe the costly failure will shake the complacency in the types of predictions that are mainstream today. 😉

  2. Nige Cook says:

    Eg, if you look at Fig 10.1 on p. 17 of “Electroweak model and constraints on new physics”, http://pdg.lbl.gov/2009/reviews/rpp2009-rev-standard-model.pdf you will see that Weinberg’s mixing angle measurements don’t fit well (within error bars) to the SM predictions in existing experiments at very high energy.

  3. Michael says:

    Hi Cliff,

    we certainly are turning a new page in particle physics, and with it begins a new chapter. We have all waited for a long time to be in this position – collisions at an energy far above the Tevatron energy, with superb detectors with which to study them. In contrast to earlier collider experiments, CMS and the others are extremely well prepared to analyze the data from many viewpoints, and you can look forward to major advances in QCD, electroweak, top, heavy flavor and other physics in the Standard Model. A theorist like yourself may be interested only in physics beyond the standard model, for which the Introduction will be written in the coming months as we complete the benchmark analyses of Standard Model processes. It is a happy and exciting time!

    regards,
    Michael

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