This Week’s Rumor

Posted on January 10, 2012 by woit

The start of the LHC 2012 physics run is still a while off, scheduled for around the beginning of April, with beam energy likely raised a bit, to 8 TeV total in the center of mass. So, it’s going to be quite a few more months before the LHC experiments have enough new data to analyze that will allow a conclusive determination of whether the evidence seen for a Higgs around 125 GeV is confirmed, with a significance high enough to claim discovery.

The results announced on December 13 were preliminary, and more complete analyses are underway, with results to be announced relatively soon. This week’s rumor is that the full CMS Higgs to gamma-gamma analysis is showing a stronger signal than the preliminary version. The bump has moved up a bit, from 123.5 GeV to 124 GeV, and the local significance is up from 2.3 to 3 sigma, with look elsewhere effect up from .8 sigma to 2.0 sigma. This strengthens a bit the evidence for a Higgs around 125 GeV. However, the best fit size of the bump is, as with ATLAS, about twice what the SM predicts. The errors are large, so quite possibly both experiments just got a bit lucky, in which case the first few months of 2012 data may not quickly add much to the significance of the signal.

For detailed discussion of issues surrounding the Higgs analyses, see this week’s workshop in Zurich: Higgs search confronts theory.

Posted in Experimental HEP News | 16 Comments

Galois Conference Videos

Posted on January 9, 2012 by woit

Last October there was a conference held in Paris to celebrate the 200th anniversary of the birth of Galois. Some of the talks were quite interesting, giving an overview of the current state of areas of mathematics in which Galois theory plays a role, in particular the Langlands conjectures. The videos of the talks are now available, see here.

The closing talk, by Alain Connes, has a certain amount of wild-eyed speculation about the “cosmic Galois group”, of the sort that I believe has inspired Arkani-Hamed recently (see the previous posting).

Roy Lisker reports (here, here and here) about his visit to Paris to attend the conference, as well as take a look at Galois’s manuscripts.

Update: It appears the Connes video is no longer there. But on his web-site you can find the slides for the conference talk, as well as another talk about Galois for a more general audience.

Posted in Uncategorized | 7 Comments

Emerging Trends

Posted on January 9, 2012 by woit

Most of the lectures from this year’s Jerusalem Winter School in Theoretical Physics are now available online. David Gross was the main organizer, and the choice of topics reflects his point of view on what is interesting these days in theoretical physics. The landscape and anthropics were pretty much completely suppressed (although Michael Dine did manage to slip in a mention, his slides are here). The idea of “string phenomenology”, i.e. getting the standard model out of a unified string theory and saying something about particle physics has fallen by the way-side.

In his summary talk (given at the beginning of the conference), Gross described the same point of view he has promoted for many years now. He thinks something is missing in our understanding of string theory (“we don’t know what string theory is”) which will somehow fix the failure of ideas about string theory unification. This failure though doesn’t matter anyway, since he now claims that string theory = QFT, based on gauge-gravity duality, and thus “string theory cannot be killed”. It’s very unclear how this equivalence claim fits together with the “we don’t know what string theory is” claim, since we do know what QFT is (we have a very good understanding of the Standard Model). It seems that Gross would like to define away much of the troubles surrounding string theory.

One idea that Gross has favored for a very long time is that string theory is telling us that we must give up our usual notions of space and time, only recovering them in some limit. Two of the series of lectures at the school were about rather grandiose attempts to do something along these lines. There were three lectures by Erik Verlinde on his ideas about “emergent gravity”. I continue to not be able to make much sense of this program. He invokes the reasonable idea that gravity is an effective long-distance force due to unknown fundamental degrees of freedom, which may very well be true. But he doesn’t seem to have anything specific to say about the fundamental degrees of freedom strong enough to get anything new out of this. There were some ideas at the end about dark matter and dark energy, but it was unclear to me whether these go anywhere.

Much more interesting was Nima Arkani-Hamed’s series of lectures on Scattering Amplitudes and the Positive Grassmannian, which he said could have been titled “How you get spacetime from the permutation group”. The first lecture started with a philosophical introduction that he said he would limit to 5 minutes, but which went on for 40. Only the first two lectures are now online.

Unlike Verlinde’s ideas, here there are very specific calculations involved. The starting point is recent progress in understanding perturbative amplitudes for N=4 SYM (and for more general gauge theories). These involve working in twistor space, and more generally working with variables such that locality and unitarity are no longer manifest. The basic mathematics and geometrical principles at work are quite different than the standard formulation of gauge theories in terms of local variables and gauge symmetry. As usual, Arkani-Hamed makes wildly enthusiastic claims. In this case, he claims to have finally found a remarkable new understanding of the subject, based on some combinatorial objects and dramatic new mathematical ideas. He does note that this still hasn’t been written up, and that it’s the third time in the past year that he has thought he had things understood, with the last two times not working out.

I’m quite curious to see where this all goes, although I confess that I’m planning on waiting a while to try and follow the details, since this is clearly very complicated work in progress, and a 4th or 5th iteration of the fundamentals may very well be on its way over the next few months. Arkani-Hamed is talking to mathematicians, including his colleague Pierre Deligne at the IAS, and says that he is moving from the old-style of Atiyah mathematics to a new-style of Grothendieck-based mathematics. I’m not sure what this means, but suspect that Atiyah’s ideas are still in there (Grassmanians, twistors and toric varieties are subjects he has been very much involved with), and that the Grothendieck business may be an artifact of talking to Deligne, who comes from that tradition. Grothendieck was the master of generality, so his ideas can be applied to a very large fraction of mathematics.

Also lecturing on amplitudes, from a much more down-to-earth point of view, was Zvi Bern. For more from both Bern and Arkani-Hamed, see the program of the recent Amplitudes 2011 conference in Michigan. Slides from Arkani-Hamed’s talk give a better idea of what he is up to, and Bern’s slides contain his summary comments about the state of the subject. He emphasizes the connections between amplitude calculations and other fields and seems to be arguing for more attention to practical results, less to “symmetry, beauty and aesthetics”. He worries that while “Today our field is one of the hottest ones around”, the long-term future is less clear: “Is our field just another (albeit long lasting) fad?”, so attention to results relevant to the rest of physics is important for long-term health.

Lots more “Amplitudes” conferences on the way, including Amplitudes 2012 in March, a conference at the Newton Institute in April, and one at the IHES in December.

Posted in Uncategorized | 13 Comments

New For 2012

Posted on January 2, 2012 by woit

To celebrate the new year, I’ve finally gotten around to updating my home page, and have updated the blog theme to the latest wordpress default.  I’ve added an “FAQ” feature, which is still under construction and should get additions as I find time.  Please let me know of anything that doesn’t work.

This coming semester I’ll be teaching the second half of our graduate course on Lie groups and representations, following on from Andrei Okounkov’s first semester. A tentative syllabus is here, and I hope to find time to update some of my older lecture notes as well as write some new ones.

The time I’ve spent the last couple years trying to learn about the Langlands program has finally gotten me to the point of thinking I understand enough to write something sensible about what the relationship might be between automorphic representations and quantum field theory. I’ll be working on that and preparing the graduate course for the next couple weeks.

One thing that was extremely helpful was Dick Gross’s lecture series here last semester. Video of the lectures is on YouTube here. Gross is an incredibly good lecturer, and this series was aimed at explaining exactly many of the things I’ve been having trouble understanding about this subject. Anyone who seriously wants to understand the representation theory point of view on number theory and the Langlands program should find these lectures helpful.

This spring the Eilenberg lecturer will be Edward Frenkel, who will be lecturing on geometric Langlands and quantum field theory. In some sense he’ll be picking up where Gross left off. He was at Gross’s last lecture, and there was a ceremonial handing over of the chalk. Of course I’ve very much looking forward to these lectures, and I expect that there will again be video available.

Posted in Langlands | 43 Comments

2011: A Banner Year for Hype

Posted on December 30, 2011 by woit

Since every blogger seems to feel it necessary to have a year-in-review posting, I thought it appropriate to point out that 2011 has been a banner year for string theory and related hype, with about twice as many editions of “This Week’s Hype” as in previous years. One reason for this is the LHC. When talking to journalists, string theorists are rarely willing to admit that the hopes of the past couple decades that string theory would make some predictions about LHC energy scale physics turned out to be a dismal failure, and this tends to lead to confused headlines. Besides the LHC though, there’s a huge on-going effort to promote other bogus “tests of string theory”. This has been going on since string theory’s lack of testability problem first started to get a lot of attention a few years ago. I see no reason for either of these two driving forces to weaken in 2012, so expect more editions of “This Week’s Hype” next year.

String theory supported by early LHC heavy ion results

Cosmologists expect the LHC to turn up evidence for the multiverse

M-theory shows that the LHC will be the world’s first time machine

Neutrons could test string theory

Octonions explain string theory

The LHC tests string theory (more heavy ions)

M-theory is a big success, predicts behavior of 4 qubits

String theory and heavy ions, yet again

Multiverse observed in the CMB – Not

String theorists suggest space wormholes possible

String theory testable with black holes and pulsars

String phenomenologists come up with predictions testable at the LHC

Superluminal neutrinos evidence for string theory

Superluminal neutrinos could be explained by string theory

CMS multi-leptons provide evidence for SUSY

A new laser will tear apart the fabric of space

A nuclear clock will test string theory

The LHC will decide between two versions of SUSY

String theory research is going well, only problems are Garrett Lisi, Lee Smolin and Peter Woit.

Gordy Kane predicts the mass of the Higgs using string theory, just days before the announcement

Superstring theory predicts three space dimensions.

Posted in This Week's Hype | 59 Comments

This Week’s Hype

Posted on December 22, 2011 by woit

The Japanese are getting in on the string theory hype business, with KEK issuing a press release today with the title: The mechanism that explains why our universe was born with 3 dimensions: a 40-year-old puzzle of superstring theory solved by supercomputer. As usual for this kind of press release, the claim is that researchers at the institution issuing the press release have finally solved the age-old problem of string theory predicting nothing. In this case the prediction is that there are 3 dimensions of space (I think that, technically, this is a “post-diction”). According to the press release:

A group of three researchers from KEK, Shizuoka University and Osaka University has for the first time revealed the way our universe was born with 3 spatial dimensions from 10-dimensional superstring theory in which spacetime has 9 spatial directions and 1 temporal direction. This result was obtained by numerical simulation on a supercomputer…

… it is expected that superstring theory allows the investigation of the birth of the universe. However, actual calculation has been intractable because the interaction between strings is strong, so all investigation thus far has been restricted to discussing various models or scenarios…

… It is almost 40 years since superstring theory was proposed as the theory of everything, extending the general theory of relativity to the scale of elementary particles. However, its validity and its usefulness remained unclear due to the difficulty of performing actual calculations. The newly obtained solution to the space-time dimensionality puzzle strongly supports the validity of the theory.

Furthermore, the establishment of a new method to analyze superstring theory using computers opens up the possibility of applying this theory to various problems. For instance, it should now be possible to provide a theoretical understanding of the inflation that is believed to have taken place in the early universe, and also the accelerating expansion of the universe, whose discovery earned the Nobel Prize in Physics this year. It is expected that superstring theory will develop further and play an important role in solving such puzzles in particle physics as the existence of the dark matter that is suggested by cosmological observations, and the Higgs particle, which is expected to be discovered by LHC experiments.

This goes back to the pre-arXiv days, before many of our current graduate students were even born, but some of us are old enough to remember similar claims being made back in the late 1980s. For example there’s the 1989 Brandenberger-Vafa paper claiming that string theory predicts 3 dimensions, using a “string gas” cosmology. I don’t remember if there was a “finally, physicists find a way to make a prediction based on string theory” press release back in 1989 or not.

Posted in This Week's Hype | 21 Comments

Short Items

Posted on December 21, 2011 by woit

A few short items:

  • The Multiverse propaganda campaign continues this month, with a piece by Alan Lightman in Harpers entitled The Accidental Universe: Science’s Crisis of Faith. The content is pretty much the usual: string theory implies an untestable multiverse, and the multiverse explains why string theory is untestable. The whole thing is wonderfully consistent, coherent, and justifies the world-view developed by leading theoretical physicists over the last 30 years. The main person quoted in the article is Alan Guth:

    Guth started his physics career in this sunny scientific world. Now sixty-four years old and a professor at MIT, he was in his early thirties when he proposed a major revision to the Big Bang theory, something called inflation…

    He wears aviator-style eyeglasses, keeps his hair long, and chain-drinks Diet Cokes. “The reason I went into theoretical physics,” Guth tells me, “is that I liked the idea that we could understand everything—i.e., the universe—in terms of mathematics and logic.” He gives a bitter laugh. We have been talking about the multiverse…

    “We had a lot more confidence in our intuition before the discovery of dark energy and the multiverse idea,” says Guth. “There will still be a lot for us to understand, but we will miss out on the fun of figuring everything out from first principles.”

    One wonders whether a young Alan Guth, considering a career in science today, would choose theoretical physics.

    The only hint anywhere in article that some physicists might feel that there is something wrong with this picture is the passing remark that some [unnamed] physicists “remain skeptical of the anthropic principle and the reliance on multiple universes to explain the values of the fundamental parameters of physics.”

  • The FY2012 DOE budget has now been finally agreed upon (see here), remarkably not even that far into FY2012. HEP does pretty well, at $791.7 million, versus $795.4 million for FY2011, a small decrease, considering that the Tevatron was running all of FY2011, is off now. More from Fermilab director Oddone here, who describes the budget as “very good news”.
  • The recent evidence for the Higgs particle found at the LHC kicks up a notch the question of who might get a Nobel prize for this discovery. Whether there’s something there at 125 GeV won’t be confirmed until too late in 2012 for a 2012 experimental prize, maybe that will be on the agenda for 2013, with the main question being who would get the prize. ATLAS and CMS are looking at very similar data, with similar analyses, releasing results in a coordinated fashion, so they should both get the prize, but there’s no obvious particular scientists to give it to.

    A theoretical Higgs prize would likely take much longer, since it will take a while to be sure that whatever is found behaves the way a Higgs should. Guralnik continues his campaign for the prize here.

  • Erik Verlinde’s claims made nearly two years ago that gravity is an entropic force have gotten a lot of attention. He doesn’t seem to have written up any elaboration of these ideas, but he comments very recently on Twitter:

    For those who wonder: the fact that the Higgs has (perhaps) been found has no influence on my ideas on gravity. These ideas remain correct.

  • Some people send me books that I enjoy in one way or another, but don’t have the time or energy to write about here. Maybe you should consider them as last-minute holiday gifts:
      A First Course in Loop Quantum Gravity, by Rodolfo Gambini and Jorge Pullin. This book explains the ideas behind loop quantum gravity at an introductory level, suitable for undergraduates, or anyone wanting as non-technical as possible of an introduction to the subject. Maybe it can be sold in a package with Barton Zwiebach’s A First Course in String Theory.
      Fascinating Mathematical People edited by Albers and Alexanderson. This contains a wonderful interview with my colleague Dusa McDuff. There’s also this exchange in the interview with Ahlfors:

      Mathematical People: How about physicists?
      Ahlfors: Well, I don’t believe in physics!
      Mathematical People: You don’t believe in physics? Why not?
      Ahlfors: Physicists are so close to physics, but they don’t know mathematics.
      Mathematical People: … There’s also a great deal of mathematics used by string theorists.
      Ahlfors: But it’s the wrong theory. I like the knot theory aspects, especially the knot theory applied to string theory. The strings are knots now, and there are these ready-made knot theorems that can be applied. That appeals to me.
      Probably physicists are important for mathematics, but they cannot be important for me in any sense. I don’t think that mathematicians should take their inspiration from physics.

      Division Algebras, Lattices, Physics, Windmill Tilting, by Geoffrey Dixon. Dixon tells his personal story about pursuing research in particle physics, trying to connect it to the mathematics of the division algebras over the reals. I’m sympathetic to the idea that this kind of algebra has something to do with the patterns we see in the SM symmetries and quantum numbers. Unfortunately I still think no one yet knows the right way to understand this.

    • Update: One more. See here for an explanation of why string theory is useful:

    Dr. Kaku explains that time machines do not violate Einstein’s laws of physics, and that – difficult though it might be – future humans would be wise to build one and slip through a wormhole to one of the alternate dimensions proposed by string theory before the cooling universe extinguishes all known life.

    Update: The Times has an article and series of letters about the Higgs/Nobel issue, see here.

    Posted in Book Reviews, Experimental HEP News, Multiverse Mania, Uncategorized | 37 Comments

    Physics on the Fringe: Smoke Rings, Circlons and Alternative Theories of Everything

    Posted on December 16, 2011 by woit

    There’s a new very thought-provoking book out from Margaret Wertheim, entitled Physics on the Fringe: Smoke Rings, Circlons and Alternative Theories of Everything. Much of the book is the beautifully told story of “outsider” physicist Jim Carter, who has spent much of his life developing an alternative fundamental physics theory based on objects he calls “circlons”.

    I have to confess that, while respecting the impetus that leads people to develop such theories, I have essentially zero sympathy for this kind of thing as science. As Wertheim explains

    In Jim’s theory of the universe, everything is mechanical; like INCOBO [an internal combustion boiler he designed], the world he imagines is made up of simple mechanically interlocking parts. As with his engine, none of the parts are complicated and you don’t need much mathematics to understand how it works…

    One way to think about what Jim Carter is doing is that he insists on a universe he can comprehend. As with the old Chryslers and Cadillacs that grace his front yard, Jim demands a cosmos he can figure out for himself.

    One way in which I’m very different than Jim Carter is that I’ve never been one for insisting on ideas that I can figure out for myself. I’m grateful for and fascinated by the fact that there’s a huge amount of knowledge about the universe out there discovered over centuries by a collaboration of a long list of brilliant people, and many places to try and learn about it. This kind of learning is a joy, and not being willing to engage with and try and appreciate the accumulated wisdom of the human race to me makes no sense. When I got to the point of learning about quantum theory, it became clear to me that this was something of great power and beauty, carrying the lesson that at a fundamental level the world is very different than the mechanical picture we derive from our human-scale intuitions. At the same time, fundamental physics and mathematics are deeply intertwined, with the deepest ideas in mathematics showing up when one tries to understand the deepest questions about physics.

    The basic problem with efforts like Carter’s is that the tools and ideas he is using just aren’t powerful enough. There’s no way they can be used to understand the universe (and test one’s understanding by calculating from theory and comparing to experiment) with anything like the power of the Standard Model or general relativity. Anyone who wants to do better than the Standard Model or GR has to come up with equally powerful ideas. It seems unlikely that this can be done by any means other than understanding well the ideas behind these theories, as well as their weaknesses, as a starting point to look for something new.

    Wertheim discusses a range of other failed and “outsider” ideas about physics. She sees an analog of Carter’s vision in the the 19th century work of prominent scientists like Tait and Thomson, who studied smoke rings as a phenomenon that might model physics at the atomic scale. More recently, Steven Wolfram’s A New Kind of Science featured claims that conventional fundamental physics could be replaced with ideas about cellular automata. Wolfram is a MacArthur winner, and Ph.D. in particle theory, so it’s not by credentials alone that one can identify “outsiders” barking up an unpromising tree.

    Remarkably, Wertheim explains that her motivation for writing the book came from attending a 2003 conference on string cosmology at the Santa Barbara KITP. This was at the beginning of the “string theory anthropic multiverse” madness which has afflicted the field since that time. In 1998 she had attended with Carter an annual meeting of the NPA (National Philosophy Alliance), a group of “outsider” physicists, and she was shocked to find the KITP hosting something that seemed not obviously different:

    That string cosmology conference I attended was by far the most surreal physics event I have been to, more bizarre than any NPA event for the very reason that this was not a fringe affair but a star-studded proceeding involving some of the most famous names in science…

    After two days, I couldn’t decide if the atmosphere was more like a children’s birthday party or the Mad Hatter’s tea party – in either case, everyone was high…

    … the attitude among the string cosmologists seemed to be that anything that wasn’t logically disallowed must be out there somewhere. Even things that weren’t allowed couldn’t be ruled out, because you never knew when the laws of nature might be bent or overruled. This wasn’t student fantasizing in some late night beer-fueled frenzy, it was the leaders of theoretical physics speaking at one of the most prestigious university campuses in the world.

    Besides the difference in credentials, there is an important difference between most recent mainstream theoretical work, even when in multiverse madness mode, and that of the “outsiders” of the NPA. Mainstream theorists recognize that they need to be compatible with the SM and GR. What they are doing is working within a conjectural extension (call it “M-theory”) of the SM and GR, claiming to preserve the successes of those theories. In principle, working this way should provide a very tight constraint on what you can do. The problem though is that one doesn’t know exactly what “M-theory” is. All one has is a list of conjectured characteristics, and these seem to be weak enough to allow a vast array of “vacua”, of such complexity as to effectively remove much in the way of constraints on what you can observe at low energy. Since the conference Wertheim attended in 2003, there have been huge efforts made to extract some non-trivial implications out of this “landscape” scenario, with no success. In practice things have in many cases degenerated to the level of “outsider” physics: anything goes, and one ends up with a group of people making ambitious claims about their wonderful theory, with no conceivable way for such claims to be tested or backed up.

    All in all, I think this is an important book, one which raises in an interesting way fundamental issues about how people think about and conduct research into fundamental theoretical physics. We’re at an unusual point in the history of the subject, one where the foundations of how this kind of science has traditionally been done are being questioned. Wertheim’s contribution to this questioning is worth paying attention to.

    For some other recent reviews, see John Horgan here, and Michael Shermer here.

    Posted in Book Reviews | 56 Comments

    Today’s Higgs Results

    Posted on December 13, 2011 by woit

    The discussion after the talks is going on at CERN now, and the results that were presented agree well with what was posted here over the past week or so. This looks a lot like a Higgs near 125 GeV. Hiccups in the streaming make it difficult to impossible to follow the discussion. Caught Heuer at the end urging caution: “intriguing hints”. This looks to me like a lot more than “intriguing hints”: it’s about what you would expect if a Higgs was there at 125 GeV, highly unlikely to see if there is no Higgs there.

    The ATLAS results are here

    Higgs to gamma gamma: 2.8 sigma bump at 126 GeV

    Higgs to ZZ to 4l: 2.1 sigma (3 events near 125 GeV)

    Higgs to WW to l nu l nu: Data not fully analyzed, 1.4 sigma excess at 126 GeV

    Combination: 3.6 sigma excess at 126 GeV.

    The CMS results are here


    Higgs to gamma gamma    : 2.34 sigma bump at 123.5 GeV.

    Higgs to ZZ to 4l: 2 events seen near 126 GeV (expect .5 background)

    Combination: 2.4 sigma excess at 124 GeV.

    I see Tommaso Dorigo is posting a detailed analysis here under the title “Firm Evidence of a Higgs Boson at Last!”. He’s likely to be the best source around for a discussion of the details.

    Update: Go to the blog of Philip Gibbs now to take a look at his (highly unofficial) plots of the combined ATLAS+CMS+Tevatron results on the Higgs. You might also want to check out Matt Strassler’s blog entry about this, which wins the award for being downbeat (“Inconclusive, As Expected”). For some reason he is incensed by Tommaso Dorigo’s “Firm Evidence”.

    Posted in Experimental HEP News | 71 Comments

    This Week’s Hype

    Posted on December 12, 2011 by woit

    The announcement at CERN tomorrow of a likely-looking signal for a 125 GeV mass Standard Model Higgs will probably unleash a flood of hype from theorists claiming this as evidence for their favorite Beyond the Standard Model scenario. One obvious problem with any such claim is that the CERN results correspond well so far to the Standard Model with no additions whatsoever, so spinning them as providing support for things like supersymmetry and string theory will require some work.

    For the last decade we have known that the Higgs mass is above 114 GeV (from LEP) and unlikely to be very much higher than that (from precision electroweak results). This summer’s LHC results disfavored masses above about 130 GeV, so for the last few months we’ve known that if the Standard Model Higgs is there, it should be between 114 and about 130 GeV. For a couple weeks news has been circulating widely from ATLAS and CMS that they are both seeing something around 125 GeV.

    First out of the gate in the hype derby is Gordy Kane, who is quoted by Davide Castelvecchi at Scientific American claiming that string theory predicts the Higgs mass to be between 122 and 129 GeV:

    “If it’s in that range it’s an incredible success for connecting string theory to the real world,” Kane says. He says he is confident that the upcoming LHC announcements, if they pan out as predicted, will constitute evidence for string theory. “I don’t think my wife will let us bet our house, but I’ll come close,” he says.

    It’s unclear exactly what he’s willing to bet the house on. If it’s just that the Higgs is in that range, this might have something to do with the plots from the experiments widely circulating privately the last few days. In a remarkable coincidence, after more than 25 years of unsuccessfully trying to extract a definite experimental prediction from string theory, Kane and collaborators were able to achieve the holy grail of the subject (a prediction of the one unknown parameter in the SM, the Higgs mass) just a week before the CERN announcement. They submitted their paper to the arXiv the evening of Monday December 5, a few days after rumors of a 125 GeV Higgs were posted on blogs Friday December 2.

    The paper deals with a “prediction” you get based on a host of assumptions about which particular class of string theory compactifications to look at. The main result is that in this particular class of models, you can relate the Higgs mass to the parameter tan(β) that occurs in SUSY extensions of the SM. As you increase tan(β) from around 2, the Higgs mass lies in a band, increasing from 105 GeV and a maximum of about 129 GeV:

    We will demonstrate that, with some broad and mild assumptions motivated by cosmological constraints, generic compactified string/M -theories with stabilized moduli and low-scale supersymmetry imply a Standard Model-like single Higgs boson with a mass 105 GeV < M_h < 129 GeV if the matter and gauge spectrum surviving below the compactification scale is that of the MSSM, as seen from Figure 1. For an extended gauge and/or matter spectrum, there can be additional contributions to M_h.

    This conclusion and Figure 1 correspond closely to what is in the slides of Kane’s talk at String Phenomenology 2011 this past August. The plot of Higgs masses as a function of tan(β) is there, giving a range of 108 GeV to 127 GeV. There is an intriguing comment on the conclusion slide:

    Single light Higgs boson, mass about 127 GeV unless gauge group extended.

    I can’t tell where the number 127 came from. Since 127 GeV is the top limit in the figure, and the wording “unless gauge group extended” is used, one guess would be that Kane meant that 127 GeV was the upper bound on the Higgs mass in this class of models.

    There’s nothing in Kane’s August talk about a 122-129 GeV range for the Higgs mass, but in the December 5 paper it appears explicitly three times:

  • In the abstract there’s:

    When the matter and gauge content below the compactification scale is that of the MSSM, it is possible to make precise predictions. In this case, we predict that there will be a single Standard Model-like Higgs boson with a calculable mass 105 GeV < M_h < 129 GeV depending on tan β (the ratio of the Higgs vevs in the MSSM). For tan β > 7, the prediction is : 122 GeV < M_h < 129 GeV.

    I don’t see where the tan β > 7 comes from, presumably it’s in one of their other papers.

  • In the introductory paragraph there’s:

    Furthermore, in G2-MSSM models [1] we find that the range of possible Higgs masses is apparently much smaller, 122 GeV < M_h <129 GeV.

  • G2-MSSM models are mentioned only briefly again in the paper, at the third occurrence of this particular mass range:

    For instance, in G2-MSSM models arising from M theory, Witten’s solution to the doublet-triplet splitting problem [38] results in μ being suppressed by about an order of magnitude. Hence, in these vacua, the Higgs mass sits in the range 122 GeV < M_h < 129 GeV.

    • Kane has chosen Lubos Motl’s blog as the place to guest post and promote this string theory “prediction”, concluding there:

    If generic compactified string theories with stabilized moduli correctly predict there is effectively a single Higgs boson and correctly predict its mass, it will be a huge success for the main directions of particle physics beyond the Standard Model, for supersymmetry and for string theory, both of which are crucial for the prediction. It will be a huge success for LHC and the accelerator physicists and experimenters who made the collider and the detectors and the analysis work. It will put us firmly on the path to understanding our own string vacuum, and toward the ultimate underlying theory. The value of the Higgs boson mass not only confirms the approach that predicts it, remarkably depending on its numerical value it may allow an approximate measurement of tan β, the μ parameter, the squark and gravitino masses, that the gauge group and matter content of the theory below the string scale is that of the MSSM, and that light (TeV scale) gluinos and dark matter are likely.

    I don’t quite see how finding a SM Higgs at 125 GeV is going to give all these different numbers and pieces of information. Kane claims that these string theory predictions also predict gluinos visible at the LHC within months from now:

    Then the gluino should be detected at LHC, and because of the heavy scalars the gluino decays are different from the ones usually discussed, being dominantly to third family quarks, top and bottom quarks. I won’t explain that here because of space and time; we can return to it as the gluinos are being detected in coming months. They have not yet been systematically searched for.

    In addition, there’s a dark matter prediction that should be tested in “1-2 years”.

    If I were Kane, I wouldn’t bet my house (or go to the press claiming the 125 GeV Higgs as a “huge success” for string theory) just yet. Assuming he’s right, within months the gluinos will be there, and his ticket to Stockholm will be assured.

    Update: My prediction in the first paragraph is coming true faster than I thought. In tonight’s hep-ph listings one finds:

    http://arxiv.org/abs/1112.2415 (m_H= 127 +/- 5 GeV)

    http://arxiv.org/abs/1112.2462 (m_H < 128 GeV)

    http://arxiv.org/abs/1112.2659 (m_H =126 +/- 3.5 GeV)

    http://arxiv.org/abs/1112.2696 (m_H > 120 GeV)

    There are going to be a lot of these…

    Update: Over at a Nature live chat, Kane is giving the public some interesting explanations:

    “for a higgs to be meaningful it must be part of a supersymmetric theory, so the superpartners should be found. The form it takes implies that gluinos should be found with masses around a TeV, maybe less, by summer, and decaying mainly into topquarks and bottom quarks.”

    “Recently we have published string theory calculations that imply the higgs boson mass is 125 GeV so if it is there are strong implications for connecting string theory to the real world, and for what the higgs discovery implies. we did that before the data.”

    “string theories are now well enough understood to predict higgs physics”

    There will be another live chat involving Kane tomorrow, this one at Science magazine.

    Update: Just took a look at the Science chat. Kane seems to have completely lost touch with reality, somehow deciding that the two experiments have reached the 5 sigma level needed to claim a discovery. As far as I know, he’s the only one in the world to think this.

    Gordy Kane:
    YES. an experimenter from one experiment can’t say that, but theorists see that two different experiments both saw a signal at about the same mass, and also saw additional channels, so it’s a discovery!

    …

    Gordy Kane:
    The 5 sigma is a criteria people have chosen. i think as soon as the data are combined from two detectors, which is entirely legitimate, then the signal will indeed be over 5 sigma.

    The following claims make about the same amount of sense as the discovery one:

    Comment From Tom
    Does the existence of a 125 Gev Higgs give any support to supersymmetry?

    Gordy Kane:
    Yes. first, for a long time it has been known that the lightest higgs boson of supersymmetry should be lighter than about 135 GeV (actually closer to 140 GeV but people make assumptions), so this is consistent. Then the supersymmetric string theories as i mentioned do predict the 125 number and it is a supersymmetric lightest higgs boson.

    Update: The hype goes on, with a column today at Nature.

    Posted in This Week's Hype | 37 Comments