Large CP violation in charmed baryon decays

We present a systematic numerical study of CP violation in two-body weak decays of antitriplet charmed baryons. In the standard model, the Δ c =1 quark level interactions inducing CP violation for the relevant decays can be grouped into two types, proportional to the CKM matrix elements λ_q= V_uqV^*_cq with q=d and q=b, respectively. Recent studies have shown that with SU(3)_F flavor symmetry, the decay amplitudes, including their strong phases, can be determined by data if contributions from λ_b are neglected. However, terms proportional to λ_b must be retained to create interferences that induce CP violation. Some of the λ_b terms can be recovered in the framework of SU(3)_F flavor symmetry, and the CP-violating rate asymmetry A_CP is predicted to be of the order of O(10^-4). We find that final state re-scattering effects, which link λ_d and λ_b terms, can help recover the missing terms. The re-scattering effects can enhance CP violation by an order of magnitude, with A_CP (Ξ_c^0 → p K^-) - A_CP (Ξ_c^0 →Σ^+ π^-) being as large as 1.87 × 10^-3. This makes it promising to observe CP violation for the first time in baryon decays.