We search for the B-0 -> p (Sigma) over bar (0)pi(-) decay with (Sigma) over bar (0) -> (Lambda) over bar gamma , where the gamma is not measured, using a data sample corresponding to an integrated luminosity of 711 fb(-1) which contains 772 x 10(6) BB pairs, collected around the gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We measure for the first time the B-0 -> p (Sigma) over bar (0)pi(-) branching fraction to be B(B-0 -> p (Sigma) over bar (0)pi(-)) = (1.17(-0.40)(+0.43)(stat) +/- 0.07(syst)) x 10(-6) with a significance of 3.0 sigma.
We simultaneously measure the branching fraction for the related channel B-0 -> p (Lambda) over bar pi(-) with much improved precision.