ARE ISOCURVATURE FLUCTUATIONS OF THE M-THEORY AXION OBSERVABLE

Banks and Dine have recently shown that the M-theory naturally accommo dates the Peccei-Quinn axion. Since the decay constant F-a of the axio n is as large as F-a similar or equal to 10(15) -10(16) GeV, the halo axion will be difficult to detect in future axion-search experiments. However, we show that isocurvature fluctuations of the M-theory axion produced at the inflationary epoch will most likely be detectable in f uture satellite experiments on anisotropies of the cosmic microwave ba ckground radiation.