Abstract
There is a long standing discrepancy between the Standard Model prediction for the muon g-2 and the value measured by the Brookhaven E821 Experiment. At present the discrepancy stands at about three standard deviations, with a comparable accuracy between experiment and theory. Two new proposals - at Fermilab and J-PARC - plan to improve the experimental uncertainty by a factor of 4, and it is expected that there will be a significant reduction in the uncertainty of the Standard Model prediction. I will review the status of the planned experiment at Fermilab, E989, which will analyse 21 times more muons than the BNL experiment and discuss how the systematic uncertainty will be reduced by a factor of 3 such that a precision of 0.14 ppm can be achieved.
Highlights
From the experimental side, the error achieved by the BNL E821 experiment is δaEμXP = 6.3 × 10−10 (0.54 ppm) [9]
An ensemble of polarized muons is introduced into a magnetic field, where they are stored for the measurement period
With the assumption that the muon velocity is transverse to the magnetic field (β · B = 0), the rate at which the spin turns relative to the momentum vector is given by the difference frequency between the spin precession and cyclotron frequencies
Summary
The muon anomaly aμ = (g − 2)/2 is a low-energy observable, which can be both measured and computed to high precision [1, 2]. Since the first precision measurement of aμ from the E821 experiment at BNL in 2001 [4], there has been a discrepancy between its experimental value and the SM prediction. This impressive result is still limited by the statistical errors, and a new experiment, E989 [10], to measure the muon anomaly to a precision of 1.6 × 10−10 (0.14 ppm) is under construction at Fermilab.
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