Resent Results and Current Status of the Muon (g–2) Experiment at BNL

Abstract

The measurement of the (g−2) value of leptons provides a unique test of theory since it is the only quantity (unlike charge and mass) calculable in the framework of the Standard Model of elementary particles. The muon (g−2) experiment E821 is currently in progress at Brookhaven National Laboratory. Four data taking runs for positive muons and one run for negative muons were successfully accomplished in 1997–2000 and 2001, respectively. Results of the 1997–2000 runs have been published, thus completing our experiment for μ⁺. Data analysis for the 2001 run for μ ⁻ is currently in progress. To provide measurement of $a_\mu = \tfrac{1} {2}(g - 2)_{\mu ^ - }$ at the same level of accuracy as for $a_{\mu ^ + } = \tfrac{1} {2}(g - 2)_{\mu ^ + }$, we need to have one more data taking run.