Direct CP violation in singly Cabibbo-suppressed D-meson decays

TL;DR

This paper explains the observed large direct CP violation difference in certain D-meson decays within the standard model by assuming significant penguin contraction effects and typical U-spin symmetry breaking.

Contribution

It demonstrates that the large CP asymmetry difference can be explained within the standard model using plausible assumptions about penguin contractions and U-spin breaking.

Findings

Large CP asymmetry difference explained within the standard model.

Consistent with observed decay rate differences.

Supports the role of penguin contractions and U-spin breaking.

Abstract

The LHCb and CDF collaborations reported a surprisingly large difference between the direct CP asymmetries, Delta A_CP, in the D0 -> K+ K- and D0 -> pi+ pi- decay modes. We show that this measurement can be plausibly explained within the standard model under the assumption of large penguin contractions matrix elements and nominal U-spin breaking. A consistent picture arises, accommodating the large difference between the decay rates, and the measured decay rates of the D -> K pi modes.