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God Particles Breeding Like Bosons
Science news in the media today is full of stories about Fermilab finding no less than five Higgs particles: God Particles Breeding Like Bosons, The ‘God Particle’ may exist in five forms, Large Hadron Collider’s rival project finds, US experiment hints at ‘multiple God particles’, Fermilab Experiment Hints at Multiple Higgs Particles. The source of these stories can be traced back to this preprint, whose authors then appeared on this radio program, leading to this Symmetry Breaking story.
On May 18 D0 claimed observation of CP violation in processes involving B-mesons of a sort that could not be explained by the SM, at a significance level of around 3 sigma. For an explanation, a good place to look is Resonaances. A violation of the SM is an extraordinary claim, so it requires some extraordinary evidence, and a 3-sigma result is not that extraordinary. The case for such a violation was strengthened by the fact that D0 and CDF had seen a 2-sigma violation of the SM in a similar CP-violating process. The May 23 theory theory preprint tries to explain these SM violations with a model involving two Higgs doublets. Two days later though, on May 25, CDF reported new results: with better data, their 2-sigma SM violation had gone away (now it is 0.8 sigma, completely consistent with the SM). Again, for a good explanation of this, see Resonaances. Somehow, the disappearance of one of the main reasons for taking all this seriously didn’t make it into the Symmetry Breaking story, or any of the flood of ridiculous stories that appeared today.
Posted in Experimental HEP News, This Week's Hype
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Predictions From David Gross
Video of David Gross’s talk at the Physics at the LHC 2010 conference is now available. He devotes much of the talk to reviewing predictions he made back in 1993 of what would happen by 2008, and making new predictions for what will happen by 2020.
The 1993 experimental predictions that didn’t work out could mostly be explained away by the SSC cancellation, which pushed investigation of TeV scale physics into the future at the LHC. In 1993 Gross predicted two light Higgs particle and superpartners (due to supersymmetry), new Z-mesons (i.e some new U(1) gauge fields) and “There will be cloudy evidence of superstrings.” His 1993 predictions about theoretical developments related to string theory didn’t work out very well:
String field theory will begin to be a useful tool and will illuminate the underlying symmetries of the theory. (not at all, he admits)
New mechanisms of string supersymmetry breaking will be discovered leading to new and definitive low energy models. (new maybe, certainly nothing definitive)
The conceptual revolution arising from the nonperturbative formulation of string theory will be in full swing, revolutionizing the concepts of space-time geometry. (“on its way, but it hasn’t really revolutionized our concepts“)
For 2020, Gross makes one striking non-scientific prediction: The US will join CERN and there will be a joint plan to build a linear collider at CERN.
His experimental predictions include a repeat of the 1993 ones (superpartners, new Z-mesons, and the Higgs, although now he only mentions one Higgs), except that he has now given up on even “cloudy” evidence of superstrings showing up at the TeV scale. His theoretical predictions include a much scaled back version of the 1993 theoretical predictions about string theory: “If we’re lucky, string theory will start to be a theory with predictions (right now we don’t understand it)”.
As far as supersymmetry goes, he says that he is “totally convinced that SUSY should be there, at the 50% level” and repeats his offer to take bets at 50/50 odds. One of the main motivations for this is the argument that SUSY can provide a suitable dark matter candidate, and he predicts observation of dark matter by 2020 at non-accelerator experiments.
Finally, he ends up with an attack on the anthropic explanation of the CC, and predicts that a better one will be found by 2020.
Update: See Lubos, who has a lot more energy than I do, for a transcription of Gross’s predictions.
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Millennium Prize Update
The Clay Mathematics Institute this past week sponsored a conference in Paris devoted to celebrating the proof of the Poincare Conjecture. This included a short ceremony on June 8th awarding the Millennium prize to Perelman, which included several laudations explaining his achievement.
The question of what happens to the million dollars remains unresolved, with the following statement issued yesterday:
The Clay Mathematics Institute has no plans for the Millennium Prize funds other than to respectfully wait for Dr. Perelman’s decision. No deadline has been fixed for his decision, and nothing has been said or will be said about the possible use of the funds. Please see the text and laudations below for what is truly important: Dr. Perelman’s great gift of a solution to the century-old conjecture of Henri Poincaré, and Thurston’s geometrization conjecture. Their solution was celebrated at a conference in Paris held June 8-9, 2010. Those present send their congratulations and best wishes to Dr. Perelman.
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LHC Update
See here for a new status report on the state of beam commissioning at the LHC. About two weeks ago a peak luminosity of about 2 x 1029cm-2s-1 was reached, using beams with 13 bunches, but each bunch relatively low intensity. Since that time, efforts have been directed at increasing the bunch intensity towards nominal values. During this process, there has been little new physics data gathered, although the plan has been to interleave physics runs on weekends with beam commissioning during the week.
On Wednesday, this plan was changed, with the focus now completely devoted to commissioning beams with nominal bunch intensity. The hope is to have collisions of high intensity bunches in two weeks or so and then provide a 4 week period of stable running for physics during August, at luminosities an order of magnitude higher than now available. The limiting factor will be the stored energy in the beam, which is approaching Tevatron levels. To go higher will require much more testing of the beam protection systems.
This week in Hamburg there was a conference people have been waiting a long time for, Physics at the LHC 2010, the first conference devoted to the presentation of LHC experimental results. So far the results are based on very low luminosities, so are only able to check that the machine is working and rediscover various well-known features of the Standard Model. As the luminosity increases, it will start to become possible to observe or rule out various exotic particles at masses not reachable by the Tevatron, as long as the cross-sections are high.
Mostly such things are unmotivated and not expected to turn up, but one story to watch is that of supersymmetry, as the LHC becomes capable of observing strongly-interacting superpartners at masses beyond the Tevatron’s reach. The MSSM includes a huge number of unknown extra parameters, so the masses of these things are unknown. Given one motivation for supersymmetry, that it is supposed to stabilize the electroweak scale, one would expect superpartners to readily show up at the new mass ranges being investigated by the LHC. The problem with this is that it’s hard to understand why they haven’t already been seen at the Tevatron, or indirectly in other experiments through the effects of higher-order processes. Taking current non-observations into account, even if one has faith that superpartners exist at masses the LHC can probe, it doesn’t seem likely that the earliest LHC data will be able to see them (for more specific analysis along these lines, see for instance this talk).
I’m quite dubious that the LHC will ever see superpartners, but many prominent theorists claim that this is likely to happen. It would be interesting to pin them down on what LHC luminosity is needed to see what they are expecting to see.
Update: A particularly noteworthy talk is that of Mike Lamont, where he gives estimates of the progression of integrated luminosity this year. They’re significantly more pessimistic than similar estimates from early this year, with about 50 inverse pb this year instead of 200, but still on track for 1000 inverse pb by late 2011.
Posted in Experimental HEP News
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Not In Our Lifetimes
A report from one of last Saturday’s events at the World Science Festival has string theorists Brian Greene and Shamit Kachru admitting that they’d be surprised to see experimental evidence for string theory in their lifetimes:
John Hockenberry, the panel’s moderator, asked Greene if he thought experimental evidence would come during his lifetime.
“I’d be surprised,” said Greene.
“And in your lifetime?” Hockenberry asked Kachru.
“…I’d be surprised,” conceded the young physicist reluctantly.
For more reports about the same panel discussion, see here and here.
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Through the Wormhole with Morgan Freeman
The Science Channel is starting up yet another show on physics tonight, with Michio Kaku’s Sci-Fi Science and Into the Universe with Steven Hawking being joined by Through the Wormhole with Morgan Freeman. The topics being covered by Freeman are the usual ones: Black Holes, Aliens, Is Time Travel Possible? What Happened Before the Big Bang? etc.
The series unfortunately first starts out by bringing religion into it, with an episode called Is There a Creator?
Did our Universe just come into being by random chance, or was it created by a God who nurtures and sustains all life?
I gather that the episode begins with speculative physics elements that include Alan Guth on the multiverse and Garrett Lisi on E8 unification, but then moves on to speculative God stuff, with a neurophysiologist followed by the “maybe we’re just a simulation” business. The New York Times today has a depressing review, by a writer who wants more of the God part and less physics:
…this opening installment, which is supposed to be about whether there’s a Creator, almost immediately degenerates into theoretical yakking by scientists about unified theories of this and missing particles of that.
Especially with recent news coverage of that particle accelerator near Geneva, it seems as if we’d been hearing about this type of physics for a long time, and the discussion never does go anywhere or have much practical relevance. Anybody got a particle big enough to plug that busted oil pipe in the Gulf of Mexico?
Anyway, after about half an hour, Mr. Freeman’s show does get intermittently interesting because it turns itself more directly to the Creator question. (Questions are pivotal to this series; future episodes include “How Did We Get Here?” and “Are We Alone?”) Doesn’t answer it, of course, but does check in on an assortment of scientists who have an assortment of theories.
One thinks our idea of God is a kind of neuropsychological tic and plunks a ridiculous-looking contraption he calls a God helmet on research subjects’ heads to try to prove it. Another suggests that we’re nothing but a computer simulation created by our own descendants. If this program can stay away from same-old science and work this territory — theories that sound a little bit crackpotish, a little bit geniusy — it might set itself apart in an increasingly crowded genre.
Update: Chad Orzel weighs in here.
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Prerequisites
The Abstruse Goose recently provided an excellent summary of how to go about learning string theory. It starts with “String Theory for Dummies”, here. Tommaso Dorigo’s latest say of the week is somehow relevant.
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Where Do They Go?
HEPAP has had a Demographics Committee since about 1999, charged with gathering data on what happens to young people in the US who enter the field of High Energy Physics (both theory and experiment). The latest report from the committee is here, but it contains more questions than answers. The data gathered show that only 10-20% of HEP graduate students end up with permanent tenured positions at HEP institutions, and the other 80-90% in some sense “leave” the field.
The committee seems to have had very little success at finding out what happens to the “leavers”, perhaps because its data-gathering method is based on questionnaires filled out by one person at each institution. Very typically, once someone “leaves” academia for a different career track, within a few years their ex-colleagues no longer know where they are or what they are doing. On the other hand, in the age of Google and Facebook, tracking people down has become rather easy, so it’s unclear why an effort hasn’t been made to do this, if not for everyone in the database, than at least for a randomly chosen statistically significant sample.
I’d certainly be curious to see some real data, but based on my personal experience I’d guess that the 80-90% number sounds right, with “leavers” going into a wide variety of different careers. The financial industry may be the most popular, but I also know many who have gone into the computer or telecommunications industries, as well as other fields in academia.
By this count, I and others who have ended up in mathematics departments count among the “leavers”. I’m very happy with how my own rather unusual career path has worked out, but have generally advised others that it relied too much on good luck for anyone else to try and emulate it. A few days ago I heard from someone at the Perimeter Institute who told me about a new “hybrid research/IT position” that they are trying to fill. The job listing is here, with a detailed description of what they are looking for here. They seem to be a looking for a candidate with both a research Ph.D. and IT experience, which is a somewhat unusual combination. A Ph.D. with little IT experience but the right skills (quick learner with patience, common sense, enjoys working with technology and helping others with their technical problems) who is interested in the position might want to try and convince them that most of the IT skills get picked up on the job anyway…
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Quick Links
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