The diquark model: New Physics effects for charm and kaon decays

Motivated by diquark exchange, we construct a class of extensions of the st andard model. These models can generate large CP conserving and CP violatin g contributions to the doubly Cabbibo suppressed decays D-0 --> K(+)pi (-) without affecting D-0-(D-0) over bar mixing, contrary to what is usually be lieved in the literature. We find an interesting specific realization of th ese models, which has the LR chiral structure and can induce novel density x density operators. It is new for non-leptonic kaon decays, and particular ly, may provide a possible solution to the DeltaI = 1/2 rule and direct CP violation, without inducing large flavour changing neutral currents. (C) 20 01 Elsevier Science B.V. All rights reserved.