Experimental Prospects for Cp Violation in Charm

Experimental sensitivity to CP violation in charm decay is beginning to approach the interesting regime (∼ 10) in which new physics may be manifest. In the early years of the 21st century, if the technical challenges can be met, the proposed BTeV experiment should have the best sensitivity for rare effects both in charm and in beauty. 1 Charm CP Violation in the Standard Model and Beyond The Standard Model (SM) predicts direct CP violation at the O(10) level in singly Cabibbo-suppressed (SCS) charm decays, due to the interference of tree-level processes with penguins (Fig. 1). The observation ofCP asymmetries substantially larger than this would be unambiguous evidence of new physics, as would almost any observation of CP violation in Cabibbo-favored (CF) or doubly Cabibbo-suppressed (DCS) charm decays. A variety of extensions of the Standard Model have been considered in which charm CP asymmetries could be as large as O(10). These include models with leptoquarks, extra Higgs doublets (e.g. non-minimal supersymmetry), a fourth generation, or right-handed weak currents. In addition, two Standard Model possibilities for large CP asymmetries in charm Invited talk presented at the Workshop on CP Violation, 3–8 July 1998, Adelaide, Australia. In D (but not charged-D) decays, O(10−3) CP asymmetries may be possible in the SM due to interference between DCS and mixing amplitudes.