First Measurement of Inclusive B → Xsη Decays

We report a first measurement of inclusive B -> X-s eta decays, where X-s is a charmless state with unit strangeness. The measurement is based on a pseudoinclusive reconstruction technique and uses a sample of 657 x 10(6)B (B) over bar pairs accumulated with the Belle detector at the KEKB e(+)e(-) collider. For M-X1 < 2.6 GeV/c(2), we measure a branching fraction of [26.1 +/- 3.0(stat)(-2.1)(+1.9)(syst)(-7.1)(+4.0)(model)] x 10(-5) and a direct CP asymmetry of A(CP) = 0.13 +/- 0.04(-0.03)(+0.02). Over half of the signal occurs in the range M-X2 > 1.8 GeV/c(2).