How Elementary Particles Die | Science 2.0– www.science20.com

How Elementary Particles Die | Science 2.0– www.science20.com
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Excerpt:

A preamble

Subnuclear physics obeys the laws of quantum mechanics,
which are quite a far cry from those of classical mechanics we are accustomed
to. For that reason, one might be inclined to believe that analogies based on
everyday life cannot come close to explaining the behavior of elementary
particles. But that is not true – in fact, many properties of elementary
particles are understandable in analogy with the behavior of classical systems,
without the need to delve into the intricacies of the quantum world. And if you
have been reading this blog for a while, you know what I think – the analogy is
a powerful didactical instrument, and it is indeed at the very core of our
learning processes.

The above has a relevance here because in this post I wish
to try and explain in as simple terms as possible how subnuclear particles
decay. I took inspiration for this from a recent conversation I had with my
son, who was asking explanations on a non-trivial rule that forbids some
quantum mechanical decay processes. The rule, called OZI (from the names of the
three theorists who proposed it in the 1970ies, Okubo, Zweig, and Iizuka),
applies to hadrons (particles made of quarks) disintegrating into other
hadrons. I will get to it later in this article, but first I want to clarify a
few more fundamental concepts about particle decays.