Enhanced charm CP asymmetries from final state interactions

TL;DR

This paper demonstrates that final state interactions within a CPT invariant two-channel framework can significantly enhance CP violation differences in D meson decays, aligning with recent experimental observations.

Contribution

It introduces a two-channel FSI model that explains the observed CP asymmetries in D meson decays, emphasizing the role of strong phase differences and inelasticity.

Findings

FSI can enhance CP asymmetries to match experimental values

The model reproduces the sign and magnitude of observed CP differences

Strong phase and inelasticity data are crucial for the results

Abstract

We show that final state interactions (FSI) within a CPT invariant two-channel framework can enhance the charge-parity (CP) violation difference between $D^0\to\pi^-\pi^+$ and $D^0\to K^-K^+$ decays up to the current experimental value. This result relies upon: (i) the dominant tree level diagram, (ii) the well-known experimental values for the $D^ 0\to\pi^-\pi^+$ and $D^ 0\to K^-K^+$ branching ratios, and (iii) the $\pi\pi \to \pi\pi$ and $\pi\pi \to K K $ scattering data to extract the strong phase difference and inelasticity. Based on well-grounded theoretical properties, we find the sign and bulk value of the $\Delta A_{CP}$ and $A_{CP}(D^0 \to \pi^-\pi^+)$ recently observed by the LHCb Collaboration.