Elephant in the room for the Nobel Prize in Physics!

On Tuesday it was announced that Makoto Kobayashi and Toshihide Maskawa have been awarded the Nobel Prize in Physics for 2008. The award is "for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature." They share the prize with Yoichiro Nambu for his work on spontaneous symmetry breaking, a process vital to the derivation of the Higgs mechanism which gives particles mass in the standard model and which, as has been well publicised, is major part of the physics to be investigated with the LHC.

The work of Kobayashi and Maskawa concerns a slightly more obscure asymmetry in nature, so called CP violation. Essentially CP asymmetry reveals a subtle difference between the weak nuclear decays of some particles and their corresponding anti-particles and forms a cornerstone in the investigation of why the universe is made of matter and not anti-matter. It was first observed experimentally in the 1960s and at the time posed a theoretical conundrum. Kobayashi and Maskawa showed in the early 1970s that this effect could be incorporated into the standard model if there are at least 3 generations of quarks. This effectively predicted the yet to be discovered top and bottom quarks. Their work built on the flavour mixing formalism developed by the Italian Nicola Cabibbo and resulted in the so called CKM (Cabibbo-Kobayashi-Maskawa) matrix.


The ultimate test of the CKM matrix came this decade with the operation of the B Factories; BELLE in Japan and BaBar in the USA. These experiments produce pairs of B mesons (particle and anti-particle) and study their decays looking for the effects of CP violation predicted by Kobayashi and Maskawa. In 2001 both collaborations reported the first experimental observations of CP violation from B meson decays, completely in agreement with the CKM matrix formalism. They have since made scores of similar measurements all consistent with the model. Imperial College has been heavily involved with the BaBar experiment (named after the eponymous cartoon elephant who is also the experiment mascot) for the duration of it's running, which was completed earlier this year. We continue to work as part of the collaboration who are now analysing the final data set. Currently the Imperial group are looking at the effects of radiative penguin decays which can further constrain the elements of the CKM matrix.

It is the success of the CKM mechanism under intense experimental scrutiny which has made Kobayashi and Maskawa deserving winners of the 2008 Nobel Prize in physics.

A Week in the North of England

We just got back from the biennial High Energy Physics conference held by the European Physical Society, this year in "The North of England, at Manchester".
The poster for the conference was a nice Lowryesque image of the city, with matchstick physicists heading for the brand new Bridgewater Hall, where the main sessions were held.

As usual with conferences, the days were filled with rather intense schedules of parallel and plenary talks, while most evenings were kept aside for social events, where attendees discuss the day's talks with their colleagues and new people they have met, and which are usually accompanied by refreshments to help the discussions along (including the Beer Tasting that was organised by Lee Thompson of Sheffield, which I certainly appreciated).

Most of these social events involved Dave Wark, our colleague on T2K at Imperial, in his role as the chair of High Energy Physics at the EPS, standing up and trying to tell jokes in a room seemingly chosen such that no one was able to hear him. The first of these was at the very impressive Manchester Town Hall, where it was clear to see (but not hear) that the Lord Mayor was enjoying Dave's speech very much indeed. I later learnt that he was rattling off the names of physicists from Manchester who had made Nobel Prize-winning contributions to our field. This list included the likes of Rutherford, Chadwick, Blackett, Bethe and several more, which is actually quite amazing.

On the Sunday off, Dave and I checked out "The Lowry" gallery, where many of LS Lowry's works are on display, along with artefacts from life in the Industrial North, with contrasting images expressed mainly through paintings, photographs, Coronation Street (the TV soap for our international readership), and Labour Party pamphlets. It is a great day out and puts Manchester as we see it now in proper perspective. It was curious to note, however, that the conference poster was for some reason not based on Lowry's Manchester as depicted in paintings such as "The Lake".

Coming out of "The Lowry", one is confronted by "The Lowry Outlet Mall". Perhaps celebrating Manchester's place as the centre of consumer culture in the North would have pleased the artist. Then again perhaps not.

One of the centrepieces of this conference is the presentation of the EPS Prizes. This year the main prize went to Makoto Kobayashi and Toshihide Maskawa, of "Kobayashi-Maskawa Theory" fame, and the K and M in the "CKM Matrix", the "C" being Nicola Cabibbo. Their paper in 1973 showed that symmetry violations that had been seen in nature, but difficult to incorporate into the understanding of physics at the time, could be described if 6 quarks existed, which were linked together through a 3 by 3 component matrix. This was at a time when the existence of quarks themselves, and whether there were 3 or 4, was a point of contention (though I would like to state that was quite a bit before my time!).

I'll leave it to our colleagues on BaBar and LHCb and DZero to remind the world of the significance of that particular Matrix....

Kobayashi was able to make it here and gave a presentation in acceptance of the prize. Although both K & M were at Kyoto University when they wrote their seminal paper, he clearly wanted to demonstrate that the work was a result of the Nagoya tradition of theoretical and experimental physics, just like the earlier MNS (Maki-Nakagawa-Sakata) matrix that we have been probing in our neutrino experiments.

Later in the week I bumped into one of my 4th year project supervisors at Kyoto, Prof Masaike, who I hadn't seen for, well, shall we just say a very very long time. He is close to Prof Maskawa (whose Quantum Field Theory course I remember sitting in), and over a pint of some nice dark Mild, he let me know that not only was Maskawa unable to make it to this particular conference, but he has actually never left the country ever in his life. Perhaps it will take even more than the EPS prize to persuade him to travel outside of Japan....