  The radiation loss of small-amplitude radially symmetric oscillons
(long-living, spatially localized, time-dependent solutions) in two- and
three-dimensional scalar field theories is computed analytically in the
small-amplitude expansion. The amplitude of the radiation is beyond all orders
in perturbation theory and it is determined using matched asymptotic series
expansions and Borel summation. The general results are illustrated on the case
of the two- and three-dimensional sine-Gordon theory and a two-dimensional
$\phi^6$ model. The analytic predictions are found to be in good agreement with
the results of numerical simulations of oscillons.
