ABSTRACT. Integrals are constructed to replace absolute moments for variables in the domain of normal attraction of an operator stable law. These integrals, called pseudomoments, improve on the geometric information contained in absolute moments. Existence and convergence to appropriate values of these integrals are shown for the variables and their affine normalized sums.
Introduction.The purpose of this note is to prove the existence and convergence of certain integrals (called pseudomoments) involving weakly convergent affine normalized sums of independent, identically distributed random vectors taking values in a finite-dimensional Euclidean space, when the normalizing operators take on a special form. The existence of these pseudomoments for the common distribution of the summands, and the convergence of the pseudomoments of the affine normalized sums to the corresponding pseudomoments of the limiting distribution, are shown to occur precisely when the latter exist, in the case of a non-Gaussian limit. The case of Gaussian limits is also covered.The pseudomoments of a distribution (for definitions, see §2) are designed to reflect the geometry of the distribution more accurately and informatively than do ordinary absolute moments. Since the great utility of affine normalization is its attention to variable decay rates in the probability tails of the one-dimensional projections (marginals) of a distribution, it is clearly an advantage to construct moment-integrals showing similar attention to these marginal tails, as we will see pseudomoments do.