DETERMINATION OF INFLATIONARY OBSERVABLES BY COSMIC MICROWAVE BACKGROUND ANISOTROPY EXPERIMENTS

Inflation produces nearly scale-invariant scalar and tenser perturbation 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 quadrupole and n(S) and n(T) are the power-law spectral indices. Even if we restrict ourselves to information from angles greater than one-third 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 than +/-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 about +/-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 several groups, can achieve the above precision. Good angular resolution is more important than high signal-to-noise ratio; for a given detector sensitivity and observing time a smaller beam provides more information than a larger beam. The uncertainties in ns and r are roughly proportional to the beam size. We briefly discuss the effects of uncertainty in the Hubble constant, baryon density, cosmological constant, and ionization history.