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 χ²/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 2σ. Incorporating final-state rescattering effects to recover the main effects of terms proportional to λ_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 ± 1.2) × 10⁻⁴ due to significant cancellations.