Two-body Cabibbo-suppressed decays of charmed baryons into vector mesons and into photons

The heavy quark effective theory and the factorization approximation are used to treat the Cabibbo-suppressed decays of charmed baryons to vector mesons, Lambda(C)-->p rho(0), p(omega), Xi(C)(+,0) --> Sigma(+,0)phi, Sigma(+,0)rho(0), Sigma(+,0)omega, and Xi(C)(0) -->Lambda phi, Lambda rho, Lambda omega. The input from two recent experimental results on Lambda(C) decays allows the estimation of the branching ratios for these modes, which turn out to be between 10(-4) and 10(-3). The long distance contribution of these transitions via vector meson dominance to the radiative weak processes Lambda(C)-->p gamma, Xi(C)-->Sigma gamma, and Xi(C)(0)-->Lambda gamma leads to quite small branching ratios, 10(-6)-10(-9); the larger value holds if a sum rule between the coupling constants of the vector mesons is broken.