It hasn’t escaped my notice that Mythbusters is back with a new season! Actually, it’s not really that new, since we’re now three (well, now four) weeks in, but I missed the first two episodes since I was out of the country. But it works out because this (actually last) week’s myth is full of interesting physics to analyze!

This past Sunday, Adam and Jamie tested the myth that if you’re driving fast enough, square wheels can actually provide a surprisingly smooth ride. At first, the idea of square wheels working at all, much less actually being smooth, can seem a little wacky, but with a bit of physical intuition, it’s not hard to convince yourself that it’s actually pretty plausible. As they explained in the show, the reason a square wheel is expected to bounce you up and down is that the distance from the axle to the bottom of the wheel changes as it turns. If you’re going slowly, every time the wheel tips over another corner, it’s going to fall down until its side is resting against the ground, taking you with it. But if you speed up …

DIS 2012 wrapped up today, and the last day of the conference was filled with another round of plenary sessions (attended by everybody). This time, though, the talks were mostly devoted to summarizing the parallel sessions which took place over the previous three days.

The conference was divided up by topic into seven working groups: structure functions, the future of DIS, diffraction and vector mesons, electroweak and new physics searches, hadronic final states, heavy flavor, and spin physics. Each of these working groups was organized by two or three conveners, who were also responsible for putting together and presenting the summary slides. I have to recognize the impressive amount of work this must have taken: in one afternoon, the conveners went through every single presentation given in the conference, and organized and adapted the main conclusions from all of them into an experimental and a theoretical summary talk for each working group. Not to mention they had to stay awake and attentive for the entire three days of talks — much easier said than done!

Anyway, the full summary presentations can be found on Indico, so if you’re interested, go ahead and check those out. I’ll post a more …

We are now in the middle of DIS 2012, the part known as the parallel sessions because, well, they are in parallel. Specifically, at any given time during the conference there will be 5-7 presentations going on in different rooms. With four sessions per day and three or four 20-minute talks per session, that means there have probably been almost 200 physics presentations given in this one building in just the past two days!

With that breadth of material, I can’t hope to cover them all — in fact, I haven’t even been able to properly “digest” just the ones I’ve been to! Unfortunately there are no particularly attention-grabbing talks like major experimental results, so nothing necessarily stands out of the pack; instead, here’s a somewhat arbitrary selection of some of the interesting presentation titles. If you are interested in this sort of thing, feel free to follow the links and read them; if not, make it into a drinking game or something.

• SM Higgs production in theory
• A theoretical review of the BSM Higgs
• Impact of LHC data on (NN)PDFs
• GPDs experimental
• Low x physics: a critical phenomenon?
• On the NNLO QCD corrections to deep-inelastic …

DIS 2012 kicked off today with a full day of plenary sessions, general talks that everyone in the conference attends. (Well, not everyone attends, but there’s nothing else going on at any rate.) The slides of all the talks presented today are available on the conference website, but here are some of the interesting results.

Results from the Tevatron and LHC

Under the principle of “save the best for last,” I am getting this out of the way first: none of the major experiments have any new results of widespread importance to present. In particular, the Higgs search stands exactly where it was two weeks ago when the Moriond results were presented. This is no surprise because, for one thing, the Higgs boson is an electroweak phenomenon whereas DIS is more about the strong force; also, any major results would be presented at a bigger conference. DIS is a fairly specialized field of study so it doesn’t attract all that many people, in the grand scheme of things.

Of course, that’s not to say there is nothing to report at all. The Tevatron experiments are finishing up analysis of their data and they have found some interesting …

Since I’ll be writing about the Deep Inelastic Scattering Workshop this week, I was planning to make a pre-conference introduction post explaining in some detail what DIS actually is. But as it turns out, one of the plenary talks tomorrow is devoted to exactly that subject — plus I’m really tired after traveling for about 18 hours and walking around the city for another four or so. So I’ll start with a quick introduction and update this with more information tomorrow.

Deep Inelastic Scattering

Deep inelastic scattering itself is a particular type of physical process that occurs when a hadron (a particle made of quarks and gluons, such as a proton) collides with a lepton (a particle that, as far as we know, has no constituents).

• It’s “deep” because the lepton has very high momentum as measured in the proton’s reference frame, so the way it behaves in the interaction can depend on very small features of the proton’s structure.
• It’s “inelastic” because some of the kinetic energy of the original two particles is lost. In modern DIS, that energy goes into splitting the proton into many outgoing particles.
• It’s “scattering” because the …

Courtesy of Sean Carroll at Cosmic Variance (and many other sources, but this is the one I happen to like linking to), the ICARUS experiment has performed a direct measurement of the speed of neutrinos coming out of CERN, and they’ve found it to be exactly consistent with the speed of light. This is hot off the physics presses, so to speak; the paper was posted on arXiv just yesterday. CERN has updated their press release with the latest information.

The neat thing about the ICARUS result is that they use the same neutrino beam as the OPERA experiment. The same neutrinos can’t be traveling at two different speeds, so clearly one or the other of these results is wrong. Given that the OPERA team has already identified a couple of construction errors in their detector, and their result was the wacky one anyway, this pretty much settles the problem with the apparent faster-than-light neutrinos: they don’t exist. It was just a detector malfunction, not any sort of strange physics.

Of course, most physicists were pretty confident that this was the case all along, but you can never be sure that something is wrong with your experiment …