Friday, March 02, 2007

Supersymmetric Higgs?

There's a fascinating article in this week's New Scientist, which suggests that evidence for the existence of supersymmetric Higgs bosons may be emerging.

Particle physicists have been searching unsuccessfully for the Higgs boson for some years. The Higgs boson is postulated in the standard model as part of the unification of the electromagnetic force and the weak nuclear force. The Higgs boson is also held to be responsible for the masses of the quarks, the leptons, and the interaction carriers of the weak force. Using the Tevatron proton-antiproton collider at Fermilab, John Conway's team have found at blip in the energy distribution of tau lepton pairs emerging from the reactions. This blip is at 160 GeV. A Higgs boson, if it exists, could decay into a pair of tau leptons, hence the interest.

Supersymmetry proposes, amongst other things, that there are multiple Higgs bosons, of various masses. At a mass of 160 GeV, some theorists are already claiming this to be evidence of a supersymmetric Higgs boson. A physicist called Jack Gunion claims this evidence accords with a version of supersymmetry called 'next-to-minimal supersymmetry'. In a sentence which almost epitomises the methodology of modern particle theorists, the New Scientist article states that "When Gunion saw Conway's graph showing a possible Higgs with a mass of 160 GeV, he realised he only had to tune the parameters of his theory by about 1 part in 10 to explain it - an amount most physicists are willing to accept," (p10, 3 March 2007). It's a bit like a golfer who goes for the pin, puts it into a green-side bunker, but then points out, with satisfaction, 'if only my swing parameters had been altered by 1 part in 10, then the ball would be next to the hole!'

If we are indeed on the cusp of going beyond the non-supersymmetric standard model, then what we need is a book which can act as a guide for us in these confusing times. We need a text which can help to explain both the mathematical structure of the standard model, and the interpretational difficulties. If only there were such a book out there...

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