This post is also on The Guardian. See also Chapter 3.5 of Smashing Physics.
Next week I am giving a talk a the SUSY 2010 conference in Bonn.
It is a bit weird that there have been seventeen of these annual SUSY (for “SUperSYmmetry”), meetings, even though there is as yet no experimental evidence for SUSY. Perhaps it’s excusable. SUSY is still the best way I’m aware of to improve the Standard Model of particle physics.
To me the three biggest arguments in its favour are: One, it plugs an important hole in the theory. Two, it sort-of-predicts Dark Matter. Three, it looks nice.
Something looking nice in Bonn.
The first is to do with why the Higgs boson is not millions of times heavier than it is. Given we don’t know whether there is a Higgs yet, that’s a pretty forward-looking concern, but it is a real worry for the credibility of the theory. Basically without it, the Standard Model looks like a coincidence on the level of one in ten-thousand-million-million (1016). This is 100 times less likely than winning the lottery jackpot two weeks running if you buy a single ticket each week. SUSY introduces some quantum cancellations which make the Higgs mass much more stable, and therefore plausible. Still, maybe the universe got lucky. Some string theorists might say we should be glad it’s not one in 10500.
The second is the most compelling to me, since astronomical observations tell us there is probably some Dark Matter out there (or else we really do not understand gravity) and many SUSY models predict a particle which would be an ideal candidate for Dark Matter. It may be right behind you. When two different branches of science have problems which seem to converge on the same solution, look out for progress.
The third point is arguable and I may argue it later, but not now.
Another feature of SUSY is its flexibility. It can appear in many different guises in an experiment, to the extent that almost any weird event we see could (and will, I bet you) be interpreted as a “hint of SUSY”.
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