Broken Symmetries, Mixing Flavors

By Sean Carroll | October 7, 2008 5:39 pm

I’m traveling, so you will have to rely on some of the many other physics bloggers talking about this year’s Nobel Prize in Physics: to Yoichiro Nambu, Makoto Kobayashi, and Toshihide Maskawa. Nambu was awarded for his work in spontaneous symmetry breaking, while Kobayashi and Maskawa for their work on flavor mixing between quarks. We’ve spoken about spontaneous symmetry breaking before; maybe someday we’ll blog about flavor mixing? The basic idea is that, when a quark decays via the weak interactions, it doesn’t just turn into a single other quark, but a mixture of three different quark flavors. A top quark, for example, can emit a W boson and turns mostly into a bottom quark, but there are trace amounts of down quark and strange quark in there as well.

Sadly, this is going to be one of those prizes which causes controversy, as some worthy winners were left out — the Nobel charter places a strict limit of three Laureates per Prize. Nambu’s Prize could easily have been shared with Jeffrey Goldstone, another pioneer of spontaneous symmetry breaking. And the Prize for Kobayashi and Maskawa could easily have been shared with Nicola Cabibbo, who worked out the case of two quark generations before it was generalized to three generations by Kobayashi and Maskawa. (There are, to be sure, important differences in the case of three generations; but it’s not called the CKM matrix for nothing.)

“Sadly,” that is, because the three winners are richly deserving, and shouldn’t have their recognition sullied by bickering over who else should have won. It’s a downside of prizes in general; not everyone can win, not everyone who deserves to. But hopefully it gets some people on the street excited about the exciting world of broken symmetries.

  • Seong-Chan

    Dear Sean,

    If you look at the official announcement, you can notice that KM were awarded for their work on ‘CP violation’ not for ‘flavor mixing’. Strictly speaking, as you know, they are two different things even they are intimately related.

    Here is the quote:
    “for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature”


  • dolo mite

    i never beleived anything peter freund said. he said nambu would be awarded the prize once the lhc began to run. i have never been more glad to eat crow. nambu is a delightful man and a great theoretical physicist. jeffrey goldstone himself would happily concede his share of recognition to this master. cosmic variance is amiss in embroiling nambu in the the ckm vs. km jing-bang, and more egregiously, not recognizing his true contribution to physics–the first observatiion, and non-trivial application, of condensed matter paradigms to particle physics. but then, its not like particle physicists/cosmologists actually know any condensed matter (ie, real) physics these days, let alone its historical importance.

  • Jeff

    Increasingly, the Nobel committee is presenting the award to a few token candidates representing a body of new work, while other major contributors are omitted for the arbitrary reason that only three people can receive the award. Thus, Kobayashi and Maskawa are rewarded while omitting Cabibbo; Nambu is praised while omitting Goldstone, Jona-Lasinio; etc. As the size of scientific collaborations (experimental or theoretical) continues to increase, the Nobel committee selections are going to appear increasingly arbitrary/capricious.

    The “sad” part is that, in the eyes of the non-experts, three people have been especially promoted to the pantheon of Nobel laureates, and they are fine physicists, but so are their coworkers who were overlooked by the prize committee. For the also-rans, their life work will still be admired by the experts, but it has been relegated to public obscurity

    If a major discovery is made at the LHC, which three physicists, out of the thousands who toil on that machine, will get the prize?

  • Andy Wood

    …the Nobel charter places a strict limit of three Laureates per Prize…

    Is this why Freeman Dyson missed out on a share of the prize that was awarded for QED?

  • none of the above

    “Nambu’s Prize could easily have been shared with Jeffrey Goldstone, another pioneer of spontaneous symmetry breaking.”

    If you read the citations and background material carefully, you will note that Nambu is being awarded the Nobel prize for “spontaneous symmetry breaking” in both the ungauged case [“Nambu-Goldstone symmetry realization”], and the gauged case [the “Higgs” mechanism], both of which he worked out and published in 1960-61 [actually he did them in reversed order; first he wrote BCS superconductivity as a non-relativistic field theory and worked out the gauge invariance of the Meissner effect = “Higgs Mechanism” [work redone in the relativistic case by Anderson, Higgs, Brout-Englert, and Guralnick-Hagen-Kibble]. Then he wrote relativistic effective theories [with Jona-Lasinio] and worked out the effects of spontaneous symmetry breaking in the ungauged case, with the resulting massless quasi-particles [Nambu-Goldstone bosons], and in particular with Lurie worked out the low-energy theorems for soft N-G Boson emission, which were the first examples of the “soft pion emission” theorems which are the content of chiral dynamics. What is most amazing is that all this was done in the context of dynamical spontaneous symmetry breaking [ie. the effective quasiparticles are dynamically generated composites, not toy scalar fields inserted by hand, as in all the other contemporary work]. I’m amazed the he could understand the underlying symmetry arguments in such a full dynamical context; his depth of physical insight is truly extraordinary.

  • Thor

    Awwww, not again. There’s a similar controversy with the prize for Medicine this year.

    They should start awarding the prize to a larger group of people: why not 20 or even 50? Its not like the general public is going to remember the names of these scientists after a few years, but it would be extremely encouraging for the scientists concerned.

    There are plenty of scientists doing really good work. And they should start awarding the prize to the ‘Team(s) led by Dr. … ‘. Seems really unfair to be categorized in the also-ran group. Team members may not get a big share of the prize money, but maybe a medal or a note – they could always say that they were a member of ‘The team led by … that was awarded the Prize’.

    Just a thought. In the age of cloud computing, swarm robotics, particle-wave dualities – at least when these concepts are becoming common knowledge, a system that awards prizes to individuals seems archaic – then again, these brilliant minds ARE reaaaallly old :) .

  • ST

    “If you read the citations and background material carefully,… ”

    I think the point being made is that such careful reading should not be necessary when picking the Nobel winners vs. the ones left out. But this is obviously hard (impossible?) in the modern age when lots of people come up with bits and pieces of an idea simultaneously.

    “What is most amazing is that all this was done in the context of dynamical spontaneous symmetry breaking [ie. the effective quasiparticles are dynamically generated composites, not toy scalar fields inserted by hand, as in all the other contemporary work].”

    Wow, that is indeed quite remarkable.

  • viggen

    the Nobel charter places a strict limit…

    This seems like an anachronism that should be changed; in this day and age, the number of people involved in individual innovations and lines of research, like the LHC, has become extremely large. Correct me if I’m wrong, but if the Higgs Boson is found, won’t it be by a good-sized team of people? That discovery will be a Nobel, just like the Bose-Einstein condensate. As such, if the prize only goes to the supervisor and the one or two people who just happened to be processing the right dataset, it is a jip for everyone else on the project who absorbed all the inevitable not-right datasets. At that point, the reward isn’t about skill and innovation; it’s just a lottery.

    I think the Nobel committee is dangerously close to judging twenty-first century science with a nineteenth century eye.

  • Nick

    I don’t necessarily think that they’re “…judging twenty-first century science with a nineteenth century eye.” The Nobel committee probably looks at it like this: any significant increase in the amount of nobel winners is a “cheapening” of their brand. Nobel winners are considered impressive because they’re rare. There’s something to be said about the kind of cult-like following that the prizes have and it’s natural for them to want to maintain that.

    I can’t speak about their choice of splits this year since I’m not on the committee but I do think it’s strange to break up a group of people who made a discovery if they want to fit two accomplishments into one nobel. It sure does sound like they have more people than nobels recently. Maybe their standards for prizes have lessened over the years.

  • Peter Coles

    The rule about numbers of winners being limited to three seems to me to be a red herring. At least in the case of the Peace Prize, the “Panel for Climate Change” was awarded a share, and that’s a lot more than 3 people.

    In any case I think they could have given Nambu & Goldstone the prize one year, and Cabibbo Kobayashi and Maskawa another. I don’t see the rush, and it would have avoided them having to split hairs about precisely what the prize was for when all these ideas are so closely connected.

  • Manny

    This is why the Higgs, Brout, and Englerts of the world are tying to ignore the GHK team that was first on the mass boson discovery and had the most complete solution. Pretending this GHK team does not exist is the best way to make the Nobel math of 3 work.

  • Manny

    If the award goes to Higgs and leaves out any of the other five (Brout, Englert, Hagen, Guralnik, Kibble) this year’s controversy will seem minor.

  • Mary

    Agree with Manny above. PH and EB solved half of the problem – namely massifying the gauge particle. GHK solved an entire problem – massifying and also showing how the deadening hand of the Goldstone theorem is avoided.


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About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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