Observation of CP violation in $D^0 \rightarrow K^- \pi^+ $ as a smoking gun for New Physics

TL;DR

This paper investigates CP violation in $D^0 ightarrow K^- \pi^+$ decays, showing Standard Model suppression and exploring potential enhancements from new physics models, with some models predicting observable asymmetries.

Contribution

It demonstrates the Standard Model's strong suppression of CP asymmetry in these decays and identifies specific new physics models that could produce detectable CP violation.

Findings

Standard Model predicts negligible CP asymmetry in $D^0 ightarrow K^- \pi^+$ decays.

Left-Right symmetric models can produce CP asymmetries up to 10%.

Two Higgs doublet models can generate CP asymmetries around 1%.

Abstract

In this paper, we study the Cabibbo favored non-leptonic $D^0$ decays into $K^- \pi^+$ decays. First we show that, within the Standard Model, the corresponding CP asymmetry is strongly suppressed and out of the experimental range even taking into account the large strong phases coming from final state Interactions. We show also that although new physics models with extra sequential generation can enhance the CP asymmetry by few orders of magnitude however the resulting CP asymmetry is still far from experimental range. The most sensitive New Physics Models to this CP asymmetry comes from no-manifest Left-Right models where a CP asymmetry up to 10% can be reached and general two Higgs models extension of SM where a CP asymmetry of order $10^{-2}$ can be obtained without being in contradiction with the experimental constraints on these models.