Semi-inclusive radiative decays of Upsilon(1S)

Abstract

We discuss in detail the photon spectrum of radiative {upsilon}(1S) decays taking into account a number of results that have recently appeared in the literature. In particular, we show how to consistently combine expressions which are valid in the upper end point region, where NRQCD factorization breaks down, with those of the central region, where NRQCD factorization holds. An excellent description of data is achieved, but theoretical errors are large.