Decoding the Amplitude Pair with Distinct CPV Phases in Charmed Baryon Decays

Abstract

In this Letter, we propose a strategy to extract information on the hierarchical amplitude pair in singly Cabibbo-suppressed (SCS) charmed baryon two-body decays, with a dominant amplitude proportional to ${\lambda }_s=V_{cs}^{\ast }{V}_{us}$ from tree operators and sub-leading one proportional to ${\lambda }_b=V_{cb}^{\ast }{V}_{ub}$ from both penguin and tree contributions. The coexistence of these two amplitudes is essential for generating nonzero CP violation (CPV) effects. Since the ${\lambda }_b$ amplitude is strongly suppressed, its experimental determination is highly challenging. However, by exploiting SU(3) flavor symmetry, which relates the well-measured Cabibbo-favored (CF) amplitudes to the SCS tree amplitudes, information on the ${\lambda }_b$ amplitude can be extracted. Using current experimental data, a conservative analysis yields ${\lambda }_b$ amplitudes can be as large as about $10\%$ of the corresponding tree amplitudes with a significance of $2.1\sigma$. In addition, the Lee-Yang parameters of these decays provide an independent probe of this elusive term. We further identify two golden decay channels, ${\Xi }_c^0\to p{K}^{-}$ and ${\Xi }_c^0\to {\Sigma }^{+}{\pi }^{-}$, which are particularly well suited for experimental studies of CPV.

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