LHC News

The LHC has just ramped up for the first time to 6.5 TeV, and has a probe beam circulating in one direction, the highest energy protons humans have ever accelerated. You can follow what’s happening here.

The BBC has gotten very excited about this whole LHC thing.


Update
: Now it’s two beams at 6.5 TeV. They just need to be careful to avoid beam collisions until the press event is organized…

Update: Maybe they weren’t careful enough. The Monday morning beam commissioning reports “Possibly first collisions”. No confirmation of this from the experiments, or officially from CERN.

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17 Responses to LHC News

  1. Gus Bici says:

    6.5 is large. 13 is gross. LHC to be renamed GHC?

  2. Peter Woit says:

    Gus,
    Luckily, it’s only 6.5/beam, 13 for two of them.

  3. Los Ranchos says:

    I think its wrong not to be excited about the LHC, whatever motivations or theories got it advertised, sold and done.

  4. Bernhard says:

    Los Ranchos,

    Sure, but not that much. Kids are watching, you know…

  5. Low Math, Meekly Interacting says:

    Think about it: there’s a pocket universe in which it makes perfect sense.

  6. EFT says:

    Could this level of energy provide a definitive test for the simplest MSSM model?
    Thanks

  7. Peter Woit says:

    EFT,
    Depends what you mean by simplest. In the simplest pictures of what SUSY models are supposed to do, evidence should have turned up at LEP and the Tevatron.

    I’ve already written a huge amount about SUSY and the LHC, and that will be the big story during the coming year so will be discussed extensively here. Right now though, no news, so it’s off-topic for this posting.

  8. EDBM says:

    A rare caption of an excitation of the BBC field! I suppose it has long since decayed to a ground state…

  9. srp says:

    The real-time LHC data page is oddly compelling. They have a nice documentation page to help you understand each element, too. On three visits to the page at widely separated times, the same beam always had the higher intensity of the two–wonder if that’s a design spec, or just the way it turned out due to normal manufacturing or operating variance.

  10. Justin says:

    Woit,

    I would like to clarify exactly your view on what one might expect from the LHC. If I’m not mistaken, you do not expect to see any fundamental deviation from the standard model because the standard model may turn out to be a basic fundamental description, one that we need to understand better. Is that more or less correct?

  11. Thomas Larsson says:

    Justin,
    The most striking results from LHC 1 are clearly that the Higgs mass is at the brink of instability and that no BSM physics has shown up. As emphasized e.g. in arxiv:1307.3536 or arxiv:1407.2122, the near-criticality of the Higgs mass means there is really no need for any new physics at all until close to the Planck scale. This may even be thought of as a principle – the principle of living dangerously.

  12. Michael Shain says:

    The authors of arxiv:1307.3536 (Investigating the near-criticality of the Higgs boson)
    in their conclusion seem to favour the multiverse :
    “an explanation of near-criticality almost necessarily requires the existence of an underlying statistical system. This drives us towards the multiverse as the most convincing framework in which one can address the issue.”

    So is the discovery of the mass of the Higgs proof of the existence of the Multiverse?

  13. Thomas Larsson says:

    Personally I don’t believe in the multiverse, but would rather expect that near-criticality is a reflection of a symmetry principle. This is in analogy with the situation in statistical physics, where critical exponents satisfy certain thermodynamic inequalities as equalities, due to an underlying scale symmetry.

    Be that as it is. The striking experimental facts are that all kinds of BSM physics have been disfavored by the LHC, and that the Higgs is balancing at the edge of instability. It must mean something.

  14. Peter Woit says:

    All,
    Please, there are too many postings on this blog about the multiverse, no need to infect the ones that aren’t with the topic.

    Justin,
    I expect that by far the most likely result from the LHC will be continued confirmation of the Standard Model (and I suspect that’s also most people’s expectation). Personally I think the most likely place to look for deviations from the Standard Model is the Higgs sector, and the LHC has a long career ahead of it studying the Higgs.
    It would be wonderful if the LHC sees something that violates the Standard Model, we desperately need a hint from experiment about how to do better. I just don’t know of any proposed new physics to be found at the LHC that has any compelling theoretical or experimental evidence to support it.

  15. srp says:

    “Beam lost due to losses in the usual position…” 4/17 03:41:29

    Is that normal ramp-down or a repeated teething problem? It says there was a “protection dump” and lists the data as part of a “post mortem” which sounds less than propitious. I’m sure they’ll get the bugs worked out but it must get nerve-wracking over there.

  16. KenW says:

    Your reply to Justin is disheartening. If a long career exploring the Higgs is what awaits the LHC, I fear that there will never be a more capable collider. People – governments – want significant new physics. Of course, results are results. But the high costs associated with these machines make it difficult to go further by this means, at least without spectacular news. Are there truly no lower cost options?

  17. Peter Woit says:

    KenW,

    It was always clear that one problem with overselling the LHC, as a machine that would discover extra dimensions, black holes, supersymmetry, etc., was that there would be a price to be paid in terms of credibility. If the LHC turns up nothing beyond the SM, that is going to make the case for a higher energy machine more difficult to make. If the LHC turns up unusual Higgs behavior, and the case for a higher energy machine to study it is made difficult because the public and decision makers think “but what about those extra dimensions, black holes, etc?” that would be a shame.

    My impression is that current studies of a larger machine than the LHC are still at a preliminary stage, with nobody talking about realistic cost estimates, so it’s unclear what the financial feasibility of these ideas is. If a larger machine can mostly be financed at current CERN budget levels, it’s a realistic possibility. If much higher budget levels are necessary, that seems unlikely. While the US, Japan or China could do such a project, there’s zero probability in the US, and I have no idea about Japan or China.

    I’m surprised there hasn’t been more discussion of the HE-LHC idea (reusing the LHC tunnel for a machine with twice the energy), since I would have thought the cost of that would be much more likely to be affordable than the more ambitious VHE-LHC ideas which would require a new, much larger, tunnel and infrastructure.

    I should make it clear that personally I think that, if technologically realistic, any of these higher energy accelerator ideas are worth the money and I hope at least one will be pursued. These are expensive machines, but affordable on the scale of the resources available to the countries involved, and more worthwhile than a lot of other things that are being funded.

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