In SUSY We Trust

New Scientist has an article in the latest issue entitled In SUSY we trust: What the LHC is really looking for, which promotes the idea that the LHC is going to discover supersymmetry. Only supersymmetry enthusiasts are quoted. I’d be curious to see some data on what the distribution of views of particle theorists is on this issue (one piece of evidence that supersymmetry skepticism is in the majority is here). Among bloggers, at one end of the spectrum is Sean Carroll, who gives a probability of 60%, at the other is Resonaances, with 0.1%. Personally, I’m with Resonaances, at least as far as conventional supersymmetric models go. The main arguments against supersymmetry, ignored in New Scientist, are that supersymmetry breaking is both necessary and hideously ugly, and if this was going to solve the hierarchy problem, we’d have seen evidence already at the Tevatron.

The article does a good job of recounting the pro-supersymmetry arguments (hierarchy problem, unification of couplings, dark matter candidate), but then goes completely off the rails with an absurd claim that supersymmetry explains confinement:

Supersymmetry’s scope does not end there. As Seiberg and his Princeton colleague Edward Witten have shown, the theory can also explain why quarks are never seen on their own, but are always corralled together by the strong force into larger particles such as protons and neutrons. In the standard model, there is no mathematical indication why that should be; with supersymmetry, it drops out of the equations naturally.

At least we’ll know one way or another within a few years from now…

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19 Responses to In SUSY We Trust

  1. Eric says:

    I would disagree with the statement that if supersymmetry solves the hierarchy problem then it should have been seen by now at the Tevatron. The Tevatron simply does not cover the entire allowed parameter space. Additionally, even if you think that supersymmetry breaking is ugly, then alternative models such as technicolor are even uglier. In any case, the indications that the Higgs has a light mass do favor SUSY.

  2. factcheck says:

    The author of the article doesn’t even list the correct institutes of the people in the article. Another excellent piece of journalism by the new scientist.

  3. Peter Woit says:


    The only inaccuracy of the kind you mention that I noticed was the description of Seiberg and Witten as affiliated with Princeton University rather than the IAS in Princeton, but that’s rather small potatoes…

  4. Bill K says:

    Eric says: “In any case, the indications that the Higgs has a light mass do favor SUSY.”

    SUSY favors a light Higgs. Which is not at all the same.

  5. Eric says:

    Bill K,
    SUSY favors a light Higgs, and the experimental data favor a light Higgs. For non-SUSY alternatives, there is no reason for the Higgs to be light. By light, I mean less than 135 GeV. As Peter says, time will tell and hopefully we’ll find out in the next few years.

  6. Pawl says:

    Another curious aspect of the NS article is that they mention Brout and Englert as well as Higgs, but leave out Guralnik, Hagen and Kibble (compare here) .

    I can’t really fault them for this — it’s really a question of whom they’ve talked to.

  7. Thomas says:

    Of course, there is also the opinion of Veltman, who stated, as recently as October 2009, that he would bet that the Higgs does not exist; in his book on particle physics he also writes that supersymmetry is only “a figment of the human mind”.

    The LHC will show us who is right.

  8. Thomas Larsson says:

    In a more recent post, the Jester said something very striking:

    “If supersymmetry is relevant at the weak scale it is in general very uncomfortable with a heavy Higgs. Well, they keep telling you that the upper limit in the MSSM is 130 GeV. But that requires stretching the parameters of the model to the point of breaking, while the natural prediction is 90-100 GeV. Indeed, not finding the Higgs at LEP is probably the primary reason to disbelieve that supersymmetry is relevant at low energies.”

  9. Arrow says:

    The probability of SUSY being correct is 10e-27 and that of Higgs being correct 10e-9.

    However with probability of 10e-2 a newly discovered particle will be wrongly identified as Higgs boson and with 10e-3 a newly discovered particle will be wrongly identified as superpartner of one of SM particles.

  10. Haelfix says:

    The actual ‘bayesian’ measure on how to determine what mass of the Higgs is most natural for supersymmetry is a complicated story. Impossible to do unless you restrict the range of models (so people talk about the constrained MssM and so forth). For instance there are models that predict a ~80-90 GeV Higgs that are not actually excluded by experiment, b/c their decays are so strange and elusive.

    The generic tendency is to prefer a light Higgs, but it is by no means exhaustive and assigning ‘weights’ to models is a mess.

    As far as what most physicists prefer, well if you add phenomenologists, it also gets messy. Everyone has their favorite pet model, but a generic MssM probably beats the nearest competitor (say extra dimension models) 3 or 4 to one.

    It has the benefit of simultaneously having the most explanatory power, and in some ways the simplest solution to the variety of problems that are out there.

  11. Mary says:

    The article has either an explicit snub or was very poorly researched. Along with Peter Higgs, Francois Englert, and Robert Brout there was another team that deserves as much, if not more, credit for the discovery of the mass boson. Gerry Guralnik at Brown University, Dick Hagen at University of Rochester, and Tom Kibble of Imperial College London wrote a paper in the same volume of Physical Review Letters in 1964 that laid out the boson in clear terms, lent mass to the gauge particle, and showed how Goldstone theorem was avoided. All three papers were recognized as milestone papers by Phys Rev Letters 50th anniversary.

    Additionally, all six were recently awarded the 2010 J. J. Sakurai Prize for Theoretical Particle Physics “For elucidation of the properties of spontaneous symmetry breaking in four-dimensional relativistic gauge theory and of the mechanism for the consistent generation of vector boson masses”.

    Steven Weinberg, who is well versed in this history and quoted throughout Ananthaswamy’s article, credits all three teams as recently as a speech he delivered last month. Ironically, this speech occurred at the Council for the Advancement of Science Writing’s annual symposium.

    With such an extensive view of history in this article, missing this GHK team certainly seems sloppy at best – or with motivation (at worst).

  12. Peter Woit says:


    Personally I think squabbling over credit for this amongst these three groups of six people is a bit absurd. The basic idea is not due to any of them, but is due to Phil Anderson, who discovered it a year and a half earlier. And yes, I know that most particle theorists didn’t understand/believe him, mistakingly thinking that his mechanism required breaking relativistic invariance. They were wrong, he was right, and showing this in detail is all that these six people did.

  13. Larry says:

    Here is a recent historical perspective with actual physics work that outlines some of the “Higgs” and GHK work above. Good read.


  14. Peter Woit says:

    Larry/Mary (who share an IP address),

    Whoever you are: I see no good reason for you to be posting anonymously, and using different pseudonyms to make it look like comments are coming from different people is dishonest and reprehensible.

    The paper you refer to is quite interesting, it answers several questions in my mind about the history of this. However, I should say that I don’t find the reaction of the authors to being told that they were scooped by Higgs, Brout-Englert, and even earlier Anderson to be very creditable. Guralnik describes Higgs/Brout/Englert as “aimed in the correct direction, they did not form the basis for serious calculation”, but I suspect few other theorists would agree with that evaluation.

    He also admits that Anderson’s work was brought to his attention, and writes: “In general these comments are correct. However, as they stand, they are entirely without the analysis and verification needed to give them any credibility.” and uses this to justify not even referring to Anderson’s work. This seems to me not at all the way to behave in the face of evidence that someone else understood the crucial points and worked out an example demonstrating them a year and a half before you did.

  15. Tim vB says:

    I’d like to take the opportunity to ask a little question about anonymity:
    I’d like to stay anonymous (well, semi-anonymous since “Tim” happens to be my first name in real life) to the readers of some blogs, but not necessarily to the hosts. Don’t the hosts have access to the email address that I enter for each post?
    This gives away my full name, plus you got my email address (you can actually contact me via this address).

  16. Peter Woit says:

    Tim vB,

    I don’t have any problem with people like you who identify themselves to me via their e-mail addresses, but use a semi-anonymous name publicly.

    I do have a problem with people who use anonymity dishonestly, engaging in “sock-puppitry” to try and advance their cause.

  17. magicmike says:

    Hi Peter,

    I’m a little confused about why you think that the article goes “completely off the rails” with an “absurd claim” that supersymmetry explains confinement. Is it just that you don’t agree with the rigor of Seiberg and Witten’s computations in their 1994 paper?

  18. Peter Woit says:


    The problem of explaining why quarks are confined is a problem about QCD, a non-supersymmetric theory. Invoking supersymmetry as an explanation of why quarks are confined is nonsense.

    The Seiberg-Witten story is about N=2 supersymmetric Yang-Mills, which has rather different behavior than QCD. I don’t think there’s any problem with their results, but they don’t explain confinement in QCD.

  19. Peter Orland says:

    There is an even older 3+1-dimensonal model which displays confinement; the (non-supersymmetric) Georgi-Glashow model with sufficiently small monopole mass and large enough (renormalized) U(1) coupling. Polyakov discussed such models in 1977. As I understand things, confinement in the Seiberg-Witten theory is very similar (and importantly some quantities can be determined exactly).

    If the monopole mass is too large, the magnetic monopoles of this model are just particles. These monopoles condense if the mass is small enough (but not zero), leading to confinement. What is much better known is that the 2+1-dimensional model confines for any coupling or mass. But there is confinement even in 3+1-dimensions, under the right circumstances.

    As Peter W. says, confinement in QCD is very different from that in such models.

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