New physics models of direct CP violation in charm decays

Abstract

In view of the recent LHCb measurement of δACP, the difierence between the time-integrated CP asymmetries in D → K +K- and D → φ+ φ- decays, we perform a comparative study of the possible impact of New Physics degrees of freedom on the direct CP asymmetries in singly Cabibbo suppressed D meson decays. We systematically discuss scenarios with a minimal set of new degrees of freedom that have renormalizable couplings to the SM particles and that are heavy enough such that their effects on the D meson decays can be described by local operators. We take into account both constraints from low energy avor observables, in particular D0 -̄D0 mixing, and from direct searches. While models that explain the large measured value for δACP with chirally enhanced chromomagnetic penguins are least constrained, we identify a few viable models that contribute to the D meson decays at tree level or through loop induced QCD penguins. We emphasize that such models motivate direct searches at the LHC. © 2012 SISSA.