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

Motivated by diquark exchange, we construct a class of extensions of the standard model. These models can generate large CP conserving and CP violating contributions to the doubly Cabbibo suppressed decays D0→K+π− without affecting D0–D0 mixing, contrary to what is usually believed in the literature. We find an interesting specific realization of these models, which has the LR chiral structure and can induce novel density×density operators. It is new for non-leptonic kaon decays, and particularly, may provide a possible solution to the ΔI=1/2 rule and direct CP violation, without inducing large flavour changing neutral currents.