Monday, 28 May 2007

Charm mixing in Physical Review Letters

My experimental collaboration, Belle, has a paper presenting evidence for the mixing of charm mesons (D0 and anti-D0) in the current issue of Physical Review Letters.

This is an example of matter turning into antimatter, and vice versa. There are four known mesons for which this can occur without "breaking the rules", and the D0 system is the last of the four in which the effect has been observed. A related phenomenon may, or may not, occur among the neutrinos. (Mixing is known to occur between different neutrino types [called "flavours"], a process usually known as neutrino oscillation due to its characteristic signature. It's still unresolved whether neutrinos and anti-neutrinos mix.) It's a pretty big deal in any case, especially for those of us who've devoted time to studying the charm sector. Mixing is one of the principal concerns of the research group I founded at Belle (and ran for many years), and so finding it is a milestone for us. And personally, when a paper has taken a large fraction of your life for a year or more, it's very satisfying for it to be completed.

A semi-technical summary of the work is available in the news section of the CERN Courier. Our paper is PRL 98, 211803, also available as a preprint at arXiv:hep-ex/0703036. The competing experiment, BaBar, presents a different kind of evidence for the same phenomenon in a paper published back-to-back with ours. These results were the talk of the conference at the electroweak session of this year's Rencontres de Moriond in March, when they were first announced, and have provoked a lot of theoretical discussion since.

Tuesday, 22 May 2007

A German beer trail

A recent article in the NYT describes a three-city beer crawl the correspondent took through Germany: Cologne, Leipzig, and Bamberg. It's good work if you can get it.

Despite having done German at school, I've spent little time in the country, and Bamberg is the only one of the three cities I've visited. I can certainly endorse the writer's comments about the local specialty, rauchbier: it really is extraordinary stuff. I don't know about "liquid bacon" as a description, since that makes it seem over-the-top. But I've had people look at me strangely when I wax lyrical about "smoked beer", trying to work out what that could possibly mean. (For the record: apparently the malt is wood-smoked.) All I can say is, try it.

My Lonely Planet guide advised dividing one's time on a short German trip between Bavaria and Berlin, with a stopover in Bamberg [or another town, whose name I've forgotten, as an alternate] along the way. I have no quarrel with that advice. Bamberg is a delightful town for a quick visit, pleasant in aspect and with a great variety of architecture in a limited space that can be walked in a day ... and the beer is like nothing else going. The food was great too.

To my delight, when I was working in Blackburg VA for several months, I discovered that one could buy Schlenkerla Rauchbier from a specialist alcohol merchant there. I've not found it anywhere else. If anyone knows how to source it in Sydney, I'd be very glad to know.

Saturday, 19 May 2007

Let's talk about sex (in the NYT)

In a minor miracle, a guest columnist in the New York Times has written an op-ed on sex and contraception that abstains from the culture war. Not a single shot is fired.

Something has to give of course: the writer (a surgeon) manages his unlikely feat by taking a shot instead at the entire political class in the States:
One statistic seems to me to give the lie to all the rhetoric about abortion, and it’s this: one in three women under the age of 45 have an abortion during their lifetime. One in three. All politicians ... say they want to make abortion at least rare ... But it’s clear they haven’t been serious ...

The burden of the argument is then that individuals need to get serious: parents, certainly, but really adults in general. (I knew that abortion was chiefly an adult issue, but I didn't know the numbers: apparently only 7% of abortions in the US occur in minors.)

Just about everyone, no doubt, would have things that they might want to say on the question, that the article leaves out. But the writer is 100% for real on all of the things that he does say. On this topic, I'll count that as a result.

(Sorry, but columnists in the NYT are in the Times Select paid section. So this is another free ad.)

Friday, 18 May 2007

The problem with Dawkins (the other one)

The other Dawkins, that is. From today's editorial in the Herald:
The Dawkins restructure of university education reduced higher education from two tiers to one, transforming or amalgamating the former colleges of advanced education into new universities, or separate institutes within existing universities. With hindsight, this development was probably a mistake.

Oh really? With hindsight it was probably a mistake? There was never anything about the idea of taking disparate institutions and calling them the same thing, that seemed like a mistake at the time?

The LHC in the news

The Large Hadron Collider has been in the news lately, with half a page in the SMH a few weeks ago, and big articles in the current New Yorker, and the New York Times science pages.

The LHC is the world's next big particle physics endeavour, and due to switch on soon; my colleagues in the particle physics groups at the Universities of Sydney and Melbourne are working on one of the experiments there, ATLAS.

The NYT article is quite ambitious, skating over a lot of ground; it also manages to be quite jaunty. And in the spirit of a picture telling a thousand words, it links to a beautiful interactive graphic that clearly distinguishes the general-purpose experiments (ATLAS and CMS) from the specialist ones (LHCb and ALICE), and explains what the detectors are doing.

The New Yorker article misses out on things like this, giving the impression (for example) that there are four experiments doing basically the same thing. I actually have a bunch of gripes with the New Yorker article: it disses the CERN cafeteria; it canvasses the idea that the LHC could destroy the world in an ice-nine-type catastrophe (it seems we'll never be free of that one); and it indulges a theoretical particle physicist in a theorist-as-performance-artist act, which is getting a little old. But if that's the worst I can say about a seven-page article in my own field, then it is clearly doing something right. The writer is engaged with the subject; she has talked to a variety of people; she is thinking.

There are, however, some bad thoughts expressed in memorable language, that seem destined to live forever. The New Yorker repeats the dread line that all science is either physics or stamp-collecting: an idea utterly without merit, but still in circulation. But what goes around can come around. Today's (Thursday's) NYT editorial on the LHC contemplates a scenario where the project fails, putting another nail in the coffin of the Age of Physics, in favour of the Age of Biology.

Yeah, right. Physicists, like everyone, are a menace when they get arrogant. So what should we do about it? Hey! I know! Let's replace them with arrogant biologists ...

Tuesday, 8 May 2007

Europa Rising

Europa rising above Jupiter’s cloud tops at 11:48 UTC on 28th February, six hours after the New Horizons spacecraft’s closest approach to the giant planet.

It's longer than usual since I've checked the NH site; this image was posted on 1st May. A summary of a NASA Science Update given then, and lots of pretty and informative pics, are also posted.

New Horizons is a small probe --- inevitably described as being the size and roughly the shape of a grand piano --- which was put on a big rocket and flung towards to outer solar system to finally visit Pluto and, we hope, some other residents of the Kuiper Belt. It was actually thrown towards a precise rendezvous with Jupiter, passing just behind that planet to pick up speed on its way. (This now-standard technique for getting around the solar system is nicely discussed in the gravity assist page at the website of another spacecraft, Cassini.) The encounter has been used as a trial run for the Pluto encounter, and to do work in the Jovian system, which has been without its own orbiter since the Galileo mission was spectacularly wound up in September '03.

The NH site states that this picture "was one of a handful of the Jupiter system that New Horizons took primarily for artistic, rather than scientific, value."

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Sunday, 6 May 2007

In praise of Parker Posey

The summer movie season in the States is on its way, and the New York Times is celebrating with a dedicated section.

Highlights are a profile of Parker Posey, who is always worth watching; an essay by Manohla Dargis on what's right with blockbusters, and A.O.Scott's characteristically precise gripe about movie adaptions of old TV programs.

And for Firefly/Serenity fans: Nathan Fillion is one of five actors singled out for special praise, for his performance in Waitress.

The Trouble with Principle

I am currently involved in a discussion on liberalism (in politics) and the role of principle (in ethics), courtesy of The Blogging Parson.

The initial posts by TBP are almost always well-informed and provocative, and lend themselves to further discussion. I guess this makes it a good blog, my semi-frequent grumbles with the content notwithstanding.

Friday, 4 May 2007

I shall call him MiniBooNE

On email today with a colleague, I've been discussing the somewhat surprising/frustrating/tantalising result posted at arXiv:0704.1500 [hep-ex] by the BooNE neutrino experiment. Well, actually, the current experiment is called MiniBooNE, which is a bit unfortunate. (In their defence, I think their idea pre-dates Mike Myers'.)

MiniBooNE was set up to test the results of the LSND experiment, which <short version>found evidence for neutrino oscillations, but evidence that didn't fit with all of the other positive neutrino-oscillation results we've been seeing; and over the years, the disconnect has been getting worse</short version>. The idea of MiniBooNE was to come at the same physics using a different approach, and either reach the same conclusion or not --- let the data decide.

Trouble is, the MiniBooNE data (for which we have waited for a long time) are confusing. The simplest explanation of LSND will not wash, but we already knew that; some convoluted explanations of LSND are still hard to rule out, which we probably suspected; and there is an unexpected anomaly in the MiniBooNE data which looks like either (a) they have missed something, or (b) something very interesting is going on.

It has been difficult to have a sensible conversation about LSND for a long time. MiniBooNE was supposed to make it easier, whereas for now, it has made it more difficult. I for one am waiting for their next paper, and the one after that, and hoping they shed some light.