Tom W. Bonner Prize in Nuclear Physics: Exploring the Nucleon Sea with Lepton-Pair Production

A surprisingly large asymmetry between the up and down sea quark distributions in the nucleon was observed in Deep-Inelastic Scattering and the lepton-pair production (Drell-Yan) experiments. In this talk, I discuss the history and current status of our knowledge on the flavor structure of the nucleon sea. I will also discuss the progress in identifying the "intrinsic" sea components in the nucleons. Prospect for future studies on nucleon sea will also be discussed.