But Kane argues that the Tevatron underperformed all along because of weak management at the lab and the Department of Energy, which funds Fermilab. “It could have performed much better and done much more,” he says.
Reaction to this from Nicholas Samios was:
“I would not trust a theorist to talk about management,” Samios says.
Tommaso Dorigo and I put on a bit of a show yesterday here in Antwerp at TEDxFlanders, and the results are already available on YouTube (and Tommaso has blog postings here and here). Doing this sort of thing for 1000 people in a venue like the Antwerp Opera House is not at all the sort of thing I’m used to, so I’m glad that it seemed to come out reasonably well.
Much of this was due to the incredible all-volunteer staff, which put on an ambitious day-long program on a shoe-string (+ crucial help from some sponsors) and pulled it off with only the most minor hitches. Christophe Cop was the “curator” and founding father of TEDxFlanders, and Thomas Goorden led the production team to victory. It was a great pleasure to meet them, many of the other volunteers, and some of the other speakers, as well as to get a chance to enjoy some time in the beautiful city of Antwerp.
Back to New York (and maybe somewhat more regular blogging) on Tuesday. Hoping to make Dick Gross’s second Eilenberg lecture on Local Langlands at the Columbia math department in the afternoon…
I’ve been hearing no interesting news from the LHC recently, about all I’ve learned is that CMS/ATLAS haven’t even decided whether it’s worth combining their latest public data (probably not, what is much more interesting is the large amount of data they are now analyzing separately). So my plan for next week is to travel to Antwerp, where I’ll try and get Tommaso Dorigo drunk and see what I can find out. We’ll both be at TEDx, he’s got more of the story here.
Adrian Cho has a wonderful long piece in Science (and podcast here) about the sociology of the two big experiments at the LHC. It gives some insight into the process by which a Higgs result is likely to emerge, including the steps being taken to make sure that some group doesn’t “parachute in” at the last moment to try and capture glory. I’m still trying to figure out who gets a Nobel prize if the Higgs is found.
For some other reading material, there’s John Ellis’s 65th birthday colloquium, an interview with Bianca Dittrich, and yet more evidence that MathOverflow rules.
I’m too busy to write much on the blog just this moment, and besides, there’s nothing of great interest I can think of that need’s writing about. So, I’ll take up commenter Shantanu’s suggestion and try and stir up a little trouble with two quick topics related to the Nobel Prize.
Unfortunately I don’t have more time now to look into this history carefully. If someone expert on this history has comments on the Dombey claims, that would be interesting.
It’s easy if you try (as John Lennon would say).
The LHC is back in business after a technical stop, getting ready to collide protons for the next couple months, perhaps reaching an integrated luminosity of about 5 inverse femtobarns. This is a factor of four higher than the luminosity used in most analyses that have been made public so far, and the latest projections are that this should allow an exclusion of a Higgs over the entire expected mass range at 95% confidence level, if such a particle really doesn’t exist.
My pre-LHC predictions (see here) of five years ago have held up well, and nothing yet has changed my view that a Higgs particle scenario and a no-Higgs scenario are equally likely. The best argument for a Higgs in the mass range of 114-145 GeV is that it’s the simplest way anyone has found of making the Standard Model work, and explains a range of precision electroweak measurements.
The best argument against the Higgs is that elementary linear scalar fields are problematic (since not asymptotically free) and esthetically displeasing (not geometrical and constrained by symmetries, so lead to lots of undetermined parameters, mainly for the Yukawas that determine the masses of all fermions). By analogy with the theory of superconductivity though, one can imagine that the Higgs makes a good low-energy effective theory (a la Landau-Ginzburg), even if there’s a more interesting fundamental theory, which may require going to a smaller distance scale (a la BCS theory). As the allowed Higgs mass range has narrowed though, I’m starting to think that there may be something to the argument that it’s implausible that the mass would end up being in the hardest mass range for colliders to examine. More likely it’s just not there, and the hardest range is the last one to fall to experiment.
By the way, I was interviewed about this on a Wired podcast (see here), not sure how it turned out. I don’t think I said anything surprising or controversial.
The imminent arrival of an experimental result deciding the issue of the SM Higgs has focused attention on what the implications will be, and here’s what I’ve been thinking:
If the SM Higgs is found, there will be rejoicing at first at CERN and within the physics community, and an appropriately proud announcement to the public. Debate will begin on who gets the Nobel: experimentalists? which of the 6000+ people at LHC/CMS/ATLAS? or theorists? Anderson/Higgs/Englert/Brout/Guralnik/Hagen/Kibble, or ? I gather Brout is no longer with us, maybe this will have to wait until the list gets down to three by attrition. Probably the best case would be for Weinberg/Salam, but they already were rewarded for the SM. Maybe the Swedes could make Weinberg’s a double. The LHC experimentalists would have an active research program for many years trying to measure the Higgs properties. Theorists though would face the gloomy prospect that these would just agree with the SM. We’d be stuck pretty much where we have been for thirty years: no clues as to how to do better than the SM.
What though if the SM Higgs gets ruled out? CERN may consider this an embarassment, but it’s actually a far more exciting result, one even more worthy of the Nobel than finding the long-sought particle. SUSY enthusiasts will claim this means it’s a SUSY Higgs, and model builders will get to work on constructing more complicated models designed to explain the result by making the Higgs even harder to see (Matt Strassler is starting to write about such models here). My guess would be though that no Higgs means the argument from esthetics was right, so adding in more scalar fields in some complex pattern isn’t a very plausible explanation of the null result.
A commenter here pointed out that this possibility was discussed during the debate over the SSC, when it was argued that, in the case of no Higgs, you would need a 40 TeV machine to look at W/Z scattering, to get information about what was really going on. The LHC should be capable of quite high luminosity, which may compensate for its lower energy in such searches, see a recent discussion here.
My own very vague favorite idea has always been that, non-perturbatively, there’s something important we’re missing in our understanding of gauge symmetry in chiral gauge theories and that this may hold the secret to the mystery of electroweak symmetry breaking. While this idea has been a motivation for research I’ve been pursuing in recent years, I can’t claim to have made any progress on it. My second real blog posting here was about this, back in 2004, leading to a torrent of abuse. Maybe if there’s no Higgs, SUSY and extra dimensions are gone, this could become a legitimate question in the eyes of mainstream theorists.
You-hoo-oo-oo-oo, you may say I’m a dreamer
But I’m not the only one…
Update: It seems that I’m definitely not the only one inspired by John Lennon recently, with CIP beating me to this a while ago.
Update: On the topic of this posting, see Slava Rychkov’s talk that just appeared on the arXiv. From the summary:
We have seen many impressive new physics limits set at this conference. But, have we ever truly believed in the models that are being pushed away? Z-prime, CMSSM, split SUSY, to name a few? I myself certainly never believed in these. Take Z-prime. In spite of what you may have heard, this is a completely unmotivated extension of the SM. It solves nothing of its problems and has nothing to do with Naturalness. Same for split SUSY, anathema to Naturalness. CMSSM is the only victim on the list for which I feel sorry, but we can’t give up on SUSY just because this straightjacketed version of it failed.
Another early casualty has been the Large Extra Dimensions scenario. But again, this was hardly a bona fide solution to the hierarchy problem. The mechanism which cuts off the Higgs mass quadratic divergence has not been concretely specified. It’s only because the idea was so original that we ever gave it the benefit of the doubt. Now with LHC limits on the (4+n)-dimensional Planck scale already a factor two above the Tevatron limits, it’s basically gone. The truth is, apart from SUSY, there are only two other motivated scenarios for TeV-scale physics: strong EWSB and Composite Higgs. I mentioned some of the signals expected in these models. Unlike CMSSM, they typically require much higher luminosity to be seen.
Lisa Randall’s new book is about to come out, it’s entitled Knocking on Heaven’s Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World. It turns out that it’s really two books in one, both of which are much better and more clearly written than her previous effort, Warped Passages. One reason might be help from well-known novelist Cormac McCarthy who is thanked (together with Lubos Motl) for extensive feedback during the book’s writing.
One of the books here is not surprising, it’s somewhat of an update of the earlier book, emphasizing the story of the LHC. This includes a very detailed explanation of the history of the LHC and how it works, together with a wonderful and clear examination of the design of the ATLAS and CMS detectors, as well as the physics they are looking for. All in all, this is about the best popular-level explanation of what is going on at the LHC that I’ve seen, up-to-date as of a few months ago.
The second book inside the book is of much wider scope. Randall’s prominence as a scientist has brought her into contact with a wide range of people (Bill Clinton’s endorsement is on the book’s cover), including artists, government officials, financiers, technologists, and a wide range of thinkers of different sorts. She has taken on the role of a public face of physics, and has written a book which is in part a very general defense of science and the materialist, rationalist world-view that modern science is based on. Her experiences with non-scientists are reflected in how she writes about a range of topics, including the notion of beauty in science, the question of how to analyze risk, the relation of religion and science and much more. Her discussions of these topics are uniformly sensible, although rather conventional and unsurprising.
In the end though, the book left me somewhat uncomfortable. Understandably, Randall is overly enthusiastic about the prospects of Randall-Sundrum models, describing them as “an idea that probably stands as good a chance as any of being right” (most theorists would assign a much higher probability to SUSY). She writes that, if correct, the LHC is expected to see KK gravitons at a mass of around 1 TeV. Recently limits on masses of such particles have been pushed up to nearly 2 TeV. These extra-dimensional models were considered interesting but not especially plausible by most theorists pre-LHC. Like SUSY, they’re starting to be ruled out by the LHC, a process which may take a while until their defenders finally admit that the expected signals just aren’t there.
The time period of Randall’s career roughly corresponds to my own (she’s a few years younger), and, as she acknowledges, her field of model-building throughout this career has been dominated by string theory-inspired SUSY and extra dimensional models. These were never very convincing, and they are now biting the dust. From the experimental side, this is an inspirational story of the triumph of the scientific method and the huge achievements of the LHC machine and detectors, but from the theoretical side, the story of this period is darker and much less inspirational. It’s not something that makes the best topic for a defense of how science is conducted.
One odd thing about the book is the title, which for Randall carries a positive meaning that she acknowledges doesn’t correspond to the very dark one of the Bob Dylan song from the soundtrack of the Sam Peckinpah film. It’s a beautiful song, but one not about finding truth, but about getting shot in the gut and facing death, hopefully not relevant to particle physics in the LHC era:
Mama, put my guns in the ground
I can’t shoot them anymore.
That long black cloud is comin’ down
I feel like I’m knockin’ on heaven’s door.
The HEP theory community is atwitter over a BBC News story LHC results put supersymmetry theory ‘on the spot’ that reports from the Lepton-Photon 2011 conference in Mumbai, where more null results relevant to supersymmetry were reported. According to the story:
Results from the Large Hadron Collider (LHC) have all but killed the simplest version of an enticing theory of sub-atomic physics.
Researchers failed to find evidence of so-called “supersymmetric” particles, which many physicists had hoped would plug holes in the current theory.
Theorists working in the field have told BBC News that they may have to come up with a completely new idea.
Joe Lykken, an organizer of the SUSY11 conference about to start at Fermilab, is getting worried:
“There’s a certain amount of worry that’s creeping into our discussions,” he told BBC News.
The worry is that the basic idea of supersymmetry might be wrong.
“It’s a beautiful idea. It explains dark matter, it explains the Higgs boson, it explains some aspects of cosmology; but that doesn’t mean it’s right.
“It could be that this whole framework has some fundamental flaws and we have to start over again and figure out a new direction,” he said.
On Twitter, there’s Carlo Rovelli gloating here, Matt Strassler (here and here) and Lisa Randall (here) claiming all is not lost. In an exchange here, Strassler notes that he’s fighting to prevent the risk of “no money for your research”. It’s unclear if he’s referring to funding for the LHC experiments or for SUSY theory. There is a real long-term danger to HEP experimental funding once the public realizes that they’re not getting the extra dimensions some have promised them, but the time to fight that risk was the many years during which hype about the LHC was rampant.
Both Strassler and Kane now seem to attach great importance to the point that, in some SUSY variants, gluino mass bounds are lower than the 1 TeV of the most popular models, more like 500 GeV. Kane goes so far as to claim that the gluino will be found, at masses below 1 TeV:
The current limit on gluino masses is not above 500 GeV. Whether the squarks are indeed so heavy is not the issue, the point is that if they are the limits on gluino masses are smaller than is often stated. I and others expect this decay to tops and bottoms is the signature by which gluinos will be found, with masses well below a TeV.
Presumably LHC searches are underway for signatures of gluinos in this mass range in these versions of SUSY. I’d be very curious to hear what the status of those searches is. If they come up negative, will SUSY proponents finally give up? New results relevant to SUSY are appearing rapidly, see the latest from CMS here and here.
For some historical perspective, something I ran across recently was a 1993 New York Times report 315 Physicists Report Failure In Search for Supersymmetry, which described null results from early days of the Tevatron. One very funny thing about the article is that much of its emphasis was on the unwieldy nature of the CDF detector, with its $65 million budget and huge number of 315 physicists.
Update: SUSY11 opens tomorrow with a talk by Murayama that incorporates the BBC News story and describes evidence against superpartners as “impressive, worrisome, but not quite there yet”. No indication of when it will get there. The title of the talk: Why do SUSY in 2011?
Update: Quite interesting reading is Michael Peskin’s summary talk at Lepton Photon. On the topic of this posting, he writes:
Before the start of LHC, I expected early discovery of supersymmetry in the jets+MET signature. Many other theorists also had this belief. But, it was not correct.
and he explains why this was (large amount of fine-tuning required if superpartner masses are even as large as 1 TeV). He also explains possible ways to construct SUSY models that evade current experimental bounds while keeping superpartner masses relevant to the fine-tuning problem from getting much too large.
This week at CERN there’s a workshop on Implications of LHC results for TeV-scale physics, which should have many interesting talks.
Update: Yet another technical talk about the state of SUSY searches that begins by reproducing the BBC story is today’s talk at CERN by John Ellis. Ellis gives an overview of SUSY fits. The regions identified by these (pre-LHC) as the most likely place for SUSY to show up have in many cases now been ruled out. With the latest LHC data, the “most likely” region moves out to higher and higher masses, with less and less of a good fit. Ellis concludes:
LHC data putting pressure on popular models.
Update: Another review of the SUSY situation is here (from the Physics in Collision conference). A quote from Altarelli:
It is not time to desperate yet… but maybe it is time for depression already.”
Today’s Wisconsin State Journal covers the String Phenomenology 2011 conference going on in Madison this week, where, according to the organizers, about 100 scientists are discussing how to “test string theory”:
The Madison conference is something of a milestone in the study of string theory, Shiu said, because it represents 10 years of thought and advances. “It means the field is moving forward, that interesting things are going on,” he said.
Kane agreed and said much of the conference focuses on the predictive powers of string theory. If the theory can predict the existence of certain particles or behaviors, Kane said, and those are then borne out by successful experiments at projects such as the Large Hadron Collider in Europe, string theory would become an accepted explanation for the workings of the universe.
Kane has a long history of making “predictions” based on string theory, including a 1997 Physics Today article String Theory is Testable, Even Supertestable, which gave a plot showing the masses of all superpartners, in the range of 50-300 GeV. His latest “generic predictions” from the conference are here(see page 22). These days most of the superpartners have for some reason moved up to 50 TeV, well beyond any hope of observation at the LHC. There’s a gluino though at a bit above current bounds of around 500 GeV, and claims that, with the right sort of analysis, this will be visible. Once this analysis gets done, one suspects the gluino will go join its friends at much higher masses. There’s also a “prediction” of the range of the Higgs mass, which happens to be within the range not yet ruled out.
Another conference going on at the moment is at Les Houches. There Luis Alvarez-Gaumé gave a survey talk about string theory, and in his conclusion he makes quite clear what he thinks of efforts like Kane’s:
One cannot make LHC-accessible predictions.
Update: After posting this, I remembered that I’d once read a much more interesting story about theoretical physics in the Wisconsin State Journal. This was from when Dirac, not string phenomenologists, came to town, and gave the paper an interview.
String theory hype is still coming fast and furious, so much so that the latest edition of This Week’s Hype needs to be a double issue. Today we learn that Black holes and pulsars could reveal extra dimensions, solving that thorny problem of testing string theory:
String theory, which attempts to unify all the known forces, calls for extra spatial dimensions beyond the three we experience. Testing the theory has proved difficult, however.
Now John Simonetti of Virginia Tech in Blacksburg and colleagues say black holes orbited by neutron stars called pulsars could do just that – if cosmic surveys can locate such pairings. “The universe contains ‘experimental’ setups we cannot produce on Earth,” he says.
The source of the hype isn’t really new though, they were featured a few years ago in an earlier edition of This Week’s Hype.
Lepton-Photon 2011 begins Monday morning, the schedule is here. It should start off with a bang, with the latest Higgs search results from ATLAS and CMS presented starting at 11:20am local time, the middle of Sunday night here. There will be a press conference on Wednesday.
If the hints of a Higgs signal seen in the data presented last month at EPS-HEP 2011 are real, they should be more pronounced in the new data (the experiments have now collected about twice as much data as that used in the analyses presented at EPS-HEP 2011). The Higgs Combination Group should by now have produced a combined analysis using last month’s data from the ATLAS + CMS and presumably that will also be released on Monday or soon thereafter. They have just today released a new document giving the details of how the combination is done: Procedure for the LHC Higgs boson search combination in summer 2011. Still holding out on us though in terms of the real data, that document just shows toy data…
Update: The latest rumor I’m hearing is that the only analyses updated with new data (nearly twice as much) since EPS-HEP that will be available Monday will be from individual channels. Analyses combining the different channels won’t be ready for another 2 to 3 weeks. I still think though that we should see the CMS+ATLAS combination of the old data shown at EPS-HEP. So, if the Higgs is there, a definitive signal may still not quite yet be available. These people do need to take a vacation sometime in the summer…
Update: The news is that CMS and ATLAS have produced new combinations (although the combination of older ATLAS + CMS data has not been released, and I’d love to know why…). The bottom line is that the hints of a Higgs around 140 GeV have weakened with the addition of more data. A simplified summary of the current situation would be:
More details available on the conference slides that should be available here. Tommaso Dorigo and Matt Strassler have commentary.
Update: Still no word on why no CMS+ATLAS combination has appeared. Philip Gibbs has hacked together an unofficial version (see here and here). Comparing the EPS data to the latest, one sees clearly that a marginally significant signal consistent with a Higgs has weakened quite a bit with the new data (and thus, there was little to no evidence for such a Higgs in the new data). Also worth reading, commentary from Jester here.
