New Physics Models of Direct CP Violation in Charm Decays

TL;DR

This paper explores various new physics models that could explain recent CP violation measurements in charm decays, analyzing their viability and implications for collider searches.

Contribution

It systematically evaluates minimal new physics scenarios affecting D meson CP asymmetries, considering experimental constraints and proposing directions for future collider tests.

Findings

Models with chromomagnetic penguins are least constrained.

Some viable models contribute at tree level or via QCD penguins.

Results motivate targeted searches at the LHC.

Abstract

In view of the recent LHCb measurement of Delta A_CP, the difference between the time-integrated CP asymmetries in D --> K+K- and D --> pi+pi- 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 flavor observables, in particular D0-D0bar mixing, and from direct searches. While models that explain the large measured value for Delta A_CP 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.