"Sign of Supersymmetry Fades Away," by Adrian Cho. Science, 21 December 2001, pp. 2249-2451.
Experimental results from early 2001 showed that a muon's magnetism was more than had been predicted by the Standard Model of Particle Physics. The discrepancy was thought to be evidence of supersymmetry, which predicts massive partners for known particles. This article reports that the explanation for the discrepancy has been found to be a minus sign. In 1995, researchers inadvertently introduced an extra minus sign into their calculations to predict the value of a muon's magnetism. The calculations have been corrected through the improvement of a mathematical component called a "form factor." With the correction, the theoretical and experimental values are now in agreement. It's not all bad news: "The scrutiny that unearthed the mistake has also improved the various calculations in ways that put the theoretical prediction on firmer ground."
--- Mike Breen