Study of the B -> X(3872)(-> D*(0)(D)over-bar(0)K decay

Abstract

We present a study of B -> X(3872)K with X(3872) decaying to D*(0)(D) over bar (0) using a sample of 657 x 10(6) B (B) over bar pairs recorded at the Gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. Both D*(0) -> D-0 gamma and D*(0) -> D-0 pi(0) decay modes are used. We find a peak of 50.1(-11.1)(+14.8) events with a mass of (3872.9(-0.4-0.5)(+0.6+0.4)) MeV/c(2), a width of d 3.9(-1.4-1.1)(+2.8+0.2)) MeV/c(2) and a product branching fraction B(B -> X(3872)K) X B(X(3872) -> D*(0)(D) over bar (0)) = (0.80 +/- 0.20 +/- 0.10) X 10(-4), where the first errors are statistical and the second ones are systematic. The significance of the signal is 6.4 sigma. The difference between the fitted mass and the D*(0)(D) over bar (0) threshold is calculated to be (1.1(-0.4-0.3)(+0.6+0.1)) MeV/c(2). We also obtain an upper limit on the product of branching fractions B(B -> Y(3940)K) X B(Y(3940) -> D*(0)(D) over bar (0) of 0.67 X 10(-4) at 90% CL.