DETERMINATION OF INFLATIONARY OBSERVABLES BY COSMIC MICROWAVE BACKGROUND ANISOTROPY EXPERIMENTS

Inflation produces nearly scale-invariant scalar and tenser perturbati on spectra which lead to anisotropy in the cosmic microwave background (CMB). The amplitudes and shapes of these spectra can be parametrized by Q(S)(2), r = Q(T)(2)/Q(S)(2) n(S), and n(T) where Q(S)(2) and Q(T) (2) are the scalar and tenser contributions to the square of the CMB q uadrupole and n(S) and n(T) are the power-law spectral indices. Even i f we restrict ourselves to information from angles greater than one-th ird of a degree, three of these observables can be measured with some precision. The combination 105(1-n S)Q(S)(2) can be known to better th an +/-0.3%. The scalar index ns can be determined to better than +/-0. 02. The ratio r can be known to about +/-0.1 for n(S) similar or equal to 1 and slightly better for smaller n(S). The precision with which n (T) can be measured depends weakly on n(S) and strongly on r. For n(S) similar or equal to 1, n(T) can be determined with a precision of abo ut +/-0.056(1.5 +/- r)/r. A full-sky experiment with a 20 are min beam using technology available today, similar to those being planned by s everal groups, can achieve the above precision. Good angular resolutio n is more important than high signal-to-noise ratio; for a given detec tor sensitivity and observing time a smaller beam provides more inform ation than a larger beam. The uncertainties in ns and r are roughly pr oportional to the beam size. We briefly discuss the effects of uncerta inty in the Hubble constant, baryon density, cosmological constant, an d ionization history.