Abstract
We present a study of the X(3872) lineshape in the decay B -> X(3872)K -> D-0(D) over bar*K-0 using a data sample of 772 x 10(6) B (B) over bar pairs collected at the Gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The peak near the threshold in the D-0(D) over bar*(0) invariant mass spectrum is fitted using a relativistic Breit-Wigner lineshape.
We determine the mass and width parameters to be m(BW) = 3873.71(-0.50)(+0.56) (stat) +/- 0.13(syst) MeV/c(2) and Gamma(BW) = 5.2(-1.5)(+2.2) (stat) +/- 0.4(syst) MeV, respectively. The branching fraction is found to be B(B+ -> X(3872)K+) x B(X(3872) -> D-0(D) over bar*(0)) = (0.97(-0.18)(+0.21) (stat) +/- 0.10(syst)) x 10(-4).
The signal from B-0 decays is observed for the first time with 5.2 sigma significance, and the ratio of branching fractions between charged and neutral B decays is measured to be B(B-0 -> X(3872)K-0)/B(B+ -> X(3872)K+) = 1.34(-0.40)(+0.47)(stat)(-0.12)(+0.10)(syst). The peak is also studied using a Flatte lineshape.
We determine the lower limit on the D (D) over bar* coupling constant g to be 0.075 at 95% credibility in the parameter region where the ratio of g to the mass difference from the D-0(D) over bar*(0) threshold is equal to -15.11 GeV-1, as measured by LHCb.