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Julian Bradfield

The Standard Model in a nut(of the sea)* shell

Everybody knows that particles are made up of quarks. Anybody who's had a youthful infatuation with particle physics, or read any popular articles about it, knows that three (main) flavours of quarks combine to form baryons in an octet and a decuplet, and so on. But all such popular accounts evade certain questions: *why* is it that nine combinations of quark/anti-quark produce an octet and a singlet of mesons? *Why* is there no spin-1/2 particle of strangeness 3? In short, why are the "multiplets" the way they are?

I hoped to find a book called something like "a bit more about particle physics for people who are reasonably mathematically sophisticated but don't actually want to take three years of theoretical physics". Such a book does exist, but it's still pretty hard going (and doesn't quite answer those questions). During the summer, I had occasion to try a little harder, with the rich resources now available to us. With help from a friendly physicist (and a good textbook), I reached a qualitative, but mathematically based, understanding of the quark model sufficient to answer my questions.

In this talk, I'll test the truth of the last sentence by trying to explain the standard model in half an hour, with enough of the mathematical model to explain the things that are hand-waved away in the popular books. (This will necessarily involve doing QM in five minutes, which may be useful for those struggling with quantum computing talks!)

*The coco de mer, or nut of the sea, is the world's largest nut, weighing up to 20kg.

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