Resummation Of Threshold Corrections In Qcd To Power Accuracy: The Drell-Yan Cross Section As A Case Study

Introduction The potential to study "new physics" at the next generation of accelerators will to a large extent depend on the ability to control the strong interaction background. Hence the present interest in making QCD predictions for hard processes as quantitative as possible, with an increasing understanding of the importance to study higher-twist effects which are suppressed by powers of the large momentum. In general, higher-twist effects reflect the "leakage" of contributions from large distances into the process of interest. The theoretical status of these corrections is well-established in the total e + e \Gamma annihilation cross section and in deep inelastic scattering (DIS) (and in related quantities), where dispersion relations relate the physical observable to the operator product expansion (OPE) of a T-product of currents at small distances. The OPE does not allow us to calculate power corrections, but one learns fro