IT'S the top contender for dark matter, the stuff thought to make up 90 per cent of the mass of the universe. Yet is the hypothetical neutralino particle really the best candidate? By reassessing the reasons for making the neutralino the front runner, physicists have opened up the field to many other dark matter candidates.
The neutralino has captivated cosmologists because it wasn't dreamed up to explain dark matter. Rather, it popped out of theories trying to address problems in the standard model of particle physics, which attempts to explain all the known particles that make up normal matter and the forces that affect them. For instance, the standard model cannot explain why the weak nuclear force is so much stronger than gravity.
The theory of supersymmetry was developed to explain such discrepancies. As yet unconfirmed, it says that every particle in the standard model has a heavier supersymmetric partner. ...
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