  Neutral B meson mixing matrix elements and B meson decay constants are
calculated. Static approximation is used for b quark and domain-wall fermion
formalism is employed for light quarks. The calculations are done on 2+1 flavor
dynamical ensembles, whose lattice spacings are 0.086 fm and 0.11 fm with a
fixed physical spatial volume of about (2.7 fm)^3. In the static quark action,
link-smearings are used to improve the signal-to-noise ratio. We employ two
kinds of link-smearings and their results are combined in taking a continuum
limit. For the matching between the lattice and the continuum theory, one-loop
perturbative calculations are used including O(a) improvements to reduce
discretization errors. We obtain SU(3) braking ratio \xi=1.222(60) in the
static limit of b quark.
