Charmed baryon decays: $SU(3{)}_F$ breaking and CP violation

Abstract

We present a comprehensive study of anti-triplet charmed baryon decays into octet baryons and pseudoscalar mesons using the $SU(3{)}_F$ flavor symmetry framework. By decomposing the flavor structure, all decay amplitudes are parametrized with a minimal set of irreducible amplitudes, and the Körner-Pati-Woo theorem further reduces the number of independent parameters from the original 35 to 19 under exact symmetry when small terms proportional to ${\lambda }_b=V_{cb}^{\ast }{V}_{ub}$ are neglected. The independent number becomes 27 with leading $SU(3{)}_F$ breaking effects. A global fit to 51 experimental measurements yields a ${\chi }^2$/d.o.f. of 2.36 and provides precise values for the decay amplitudes. Notable discrepancies are observed in the fitted branching fractions of ${\Xi }_c^0\to {\Xi }^{-}{\pi }^{+}$ and ${\Xi }_c^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}$, which exceed current measurements by more than $2\sigma$. Incorporating final-state rescattering effects to recover the main effects of terms proportional to ${\lambda }_b$, we predict enhanced CP violation, with $A_{CP}$ reaching up to $10^{-3}$ in golden channels such as ${\Xi }_c^0\to p{K}^{-}$ and ${\Xi }_c^0\to {\Sigma }^{+}{\pi }^{-}$. Our analysis also finds that the branching ratio for ${\Xi }_c^{+}\to \Lambda {\pi }^{+}$ is enhanced to $(9.7\pm 1.2)\times 10^{-4}$ due to significant cancellations.

Comments: 14 pages, 9 figures