There’s a potentially important new paper on the arXiv from Terry Tomboulis, entitled Confinement for all values of the coupling in four-dimensional SU(2) gauge theory. Tomboulis claims to prove that SU(2) lattice gauge theory has confining behavior (area law fall off of Wilson loops at large distances) for all values of the coupling at the scale of the cutoff, no matter how small. This conjectured behavior is something that quite a few people tried to prove during the late seventies and eighties, without success. Tomboulis is one of the few people who has kept seriously working on the problem, and it looks like he may have finally gotten there. The method he is using goes back to work of ‘t Hooft in the late 1970s, and involves considering the ratio of the partition function with an external flux in the center of SU(2) and the partition function with no such flux. For a recent review article about this whole line of thinking by Jeff Greensite, see here. For shorter, less technical articles by Tomboulis about earlier results in the program he has been pursuing, see here, here, and here.
As far as I can tell, even if this holds up, it won’t get Tomboulis the million-dollar Clay prize being offered for the solution of the Yang-Mills Millenium Prize Problem. There the problem is stated as rigorously constructing Yang-Mills for any gauge group, not just SU(2), showing that it has the expected properties, and a mass gap. I don’t know whether Tomboulis’s methods can prove that there is a mass gap. In any case, I also don’t know why the Clay prize asks for a mass gap rather than confinement, which seems more physically relevant.
The latest HEPAP meeting was this past weekend in Washington and presentations are available here. The news from the DOE is that it looks like Congress will approve a FY 2008 HEP budget at or above the White House request of $782.2 million, an increase of at least 4%. This will include $60 million for ILC R and D (up from $42 million in FY2007). This will include funds for site surveys in the US, which in principle will include sites other than Fermilab, although I find it hard to believe a US site other than Fermilab would end up being chosen.
There’s a report from the University Research subpanel that puts near the top of its recommendations “A higher priority in the overall HEP program should be given to funding directed at university-based theoretical particle physics for the purpose of increasing the number of HEP-grant supported graduate students.” Given the continuing high ratio between students getting Ph.Ds in particle theory and jobs for them when they get out, I would have thought the priority would go to finding ways to fund jobs for students once they get out, rather than increasing the number of Ph.Ds.
There’s a recommendation from the P5 panel that the Tevatron should definitely run through FY2009, and in September they’ll start looking at the case for running even longer than that. There’s also a discussion of “European reaction” to comments from the DOE’s Ray Ohrbach that the US needs a plan in case the ILC doesn’t start happening soon. Typical reaction from the Europeans was said to be that the US is not a reliable partner, and makes unilateral decisions without consultation. CERN has recently been promised a budget supplement over the next few years that could pay for an LHC upgrade (they were in hock over the LHC), and by 2016 that would be done and paid for. At that time CERN will have money to spend on a new big project and a higher energy linear collider using CLIC technology would be a possibility (the semi-joke made was that the work advancing this possibility is now going on mainly in the US, at SLAC).
A progress report from the Fermilab Steering Group, which is supposed to report to the Director on Aug. 1, included extensive discussion of “Project X”, a proposal to dramatically increase the power of proton beams by building an 8 GeV proton linac. Part of the idea is that building this smaller linac would help get experience needed for doing the ILC.
According to CNN, one of the “Geniuses who will change your life” is Harvard’s (soon to be Princeton’s) Nima Arkani-Hamed, who is described as follows:
Nima Arkani-Hamed thinks big. He has a theory that our universe is one of an infinite number of universes — meaning the largest thing we can wrap our minds around is actually pretty tiny
He didn’t pull the “multiverse” out of thin air, though. After becoming a Harvard professor at age 30, Arkani-Hamed first made a name for himself by suggesting that our universe is five-dimensional. Then he moved on to the multiverse, theorizing that our own universe has a hidden feature called “split supersymmetry,” which means that half of all particles have partner particles.
The theory will be tested soon in Switzerland’s brand-new Large Hadron Collider (LHC), and if the LHC finds Arkani-Hamed’s partner particles, it could prove that the multiverse is real — and that our place in it is that much smaller.
The claim that if you see split supersymmetry, this proves that the multiverse is real seems pretty much laughable to me.
Clifford Johnson is in Aspen, at what its director describes as a “summer camp for physicists”. He has a posting about his experiences there, describing how the big topic of conversation is the recent Strings 2007 conference. He asks for people to write in telling about which of the Strings 2007 talks they found most interesting (although so far, a half day later, no one seems to have taken him up on this). Like Jacques Distler, after Witten’s talk, Clifford seems to be most impressed by Seiberg’s talk on BMSSM (Beyond the Minimal Supersymmetric Standard Model) physics, based on his recent paper with Dine and Thomas. The idea is that, even with its 105 extra parameters, the MSSM still requires a lot of fine-tuning to get around the LEP bound on the Higgs mass, so you should analyze adding even more terms to the Standard Model besides the minimal supersymmetric ones. Distler was very excited by the Seiberg talk, arguing that these results should have been found years ago but weren’t. Various people wrote into his blog to point out to him that this wasn’t right, that mostly these things had been done a while ago, including by several authors back in 2003 (see hep-ph/0301121 and hep-ph/0310137). Seiberg et. al. issued a revised version of their paper where they added quite a few references, including one to work back in 1999 by Alessandro Strumia (hep-ph/9906266) where he already discussed the impact of the two operators identified by Dine et. al on the Higgs mass.
Update: The debate over string theory really has reached the general public, at least in New York: a few months ago there was a cartoon in the New Yorker, this week, it has made the New York Magazine web-site celebrity coverage.
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