New Physics signature in $D^0 (\bar{D}^0)\to f$ effective width asymmetries

TL;DR

This paper estimates the potential size of CP violation asymmetries in $D^0$ meson decays, exploring standard and beyond standard model physics to understand possible new physics signatures in these asymmetries.

Contribution

The paper provides upper bounds on $A_{ ext{Gamma}}^f$ in the standard model and beyond, highlighting the potential for new physics to influence CP violation in $D^0$ decays.

Findings

Standard model predicts $|A_{ ext{Gamma}}^f| oxed{ ext{less than } 10^{-10}}$.

Two Higgs doublet model yields $|A_{ ext{Gamma}}^f| oxed{ ext{less than } 10^{-7}}$.

Left-right symmetric models allow $|A_{ ext{Gamma}}^f| oxed{ ext{up to } 10^{-5}}$, close to experimental bounds.

Abstract

Violation of charge conjugation-parity ($\rm CP$) symmetry plays a major rule in the dominance of matter in our universe. A kind of $\rm CP$ violation results from the asymmetry of the life time measured in $M^0$ and $\bar M^0$, here $M$ is a heavy meson, decays to final states which is referred in the literature as $A_{\Gamma}^f$. In this paper, we give an estimation of the upper bound on $|A_{\Gamma}^f|$ for the Cabibbo Favored $D^0 \rightarrow K^- \pi^+$ decay process in different models. We show that in the standard model, $|A_{\Gamma}^f| \lesssim\mathcal{O} (10^{-10})$. Recently a bound on $A_{\Gamma}^f$ has been obtained: $(A^f_{\Gamma})^{Exp.}= (1.6 \pm 1)\times 10^{-4}$. This result motivates further studies on $A_{\Gamma}^f$ in beyond standard model physics. In the framework of two Higgs doublet model with generic Yukawa structure, we show that $|A_\Gamma^{f}|\lesssim \mathcal{O} (10^{-7})$ which is several orders of magnitude smaller than the current experimental value. Finally, in the framework of left-right symmetric models in which the mixing between the left and the right gauge bosons is allowed and the left-right symmetry is not manifest at unification scale, we find that $A_{\Gamma}^f$ can be as large as $|A_{\Gamma}^f|\lesssim\mathcal{O} (10^{-5})$ which is one order of magnitude smaller than the experimentally measured value by LHCb collaborators.