New physics in singly Cabibbo-suppressed D decays

A U-spin relation among four ratios of amplitudes for D0→π+K−,K+π−,K+K−,π+π−D0→π+K−,K+π−,K+K−,π+π−, including first, second and third order U-spin breaking, has been derived recently with a precision of 10−310−3. We study effects of new |ΔC|=1|ΔC|=1 operators on this relation. We find that it is not affected by U-spin scalar operators, including QCD penguin and chromomagnetic dipole operators occurring in supersymmetric and extra-dimensional models. The relation is modified by new U=1U=1 operators with a sensitivity of a few percent characteristic of second order U-spin breaking. Combining this relation with CP asymmetries in D0→K+K−,π+π−D0→K+K−,π+π− leads to a more solid constraint on U=1U=1 operators than from asymmetries alone.