Measurement of the branching fraction and search for $CP$ violation in $D^0\rightarrow K^0_S\,K^0_S\,\pi^+\pi^-$ decays at Belle

TL;DR

This paper measures the branching fraction of a specific D0 decay and searches for CP violation using Belle data, providing insights into potential new physics beyond the Standard Model.

Contribution

First measurement of the branching fraction for D0→K0sK0sπ+π− and a search for CP violation in this decay mode using Belle data.

Findings

Branching fraction measured relative to normalization channel

No significant CP violation observed

Results constrain new physics models

Abstract

We measure the branching fraction for the Singly Cabibbo-suppressed decay $D^0\rightarrow K^0_S\,K^0_S\,\pi^+\pi^-$, and we search for $CP$ violation via a measurement of the $CP$ asymmetry $A^{}_{CP}$ and also the $T$-odd triple-product asymmetry $a_{CP}^{T}$. The later two measurements are complementary. We use 922~fb$^{-1}$ of data recorded by the Belle experiment, which ran at the KEKB asymmetric-energy $e^+ e^-$ collider. The branching fraction is measured relative to the Cabibbo-favored normalization channel $D^0\rightarrow K^0_S\,\pi^+\pi^-$. Singly Cabibbo-suppressed charm decays are expected to have especially good sensitivity to new physics effects.