  The B* B pi coupling is a fundamental parameter of chiral effective
Lagrangian with heavy-light mesons and can constrain the B->pi l nu form factor
in the soft pion limit which will be useful for precise determination of |Vub|.
We compute the B* B pi coupling with the static heavy quark and the
O(a)-improved Wilson light quark. Simulations are carried out with n_f=2
unquenched 12^3x24 lattices at beta=1.80 generated by CP-PACS collaboration.
Following the quenched study by Negishi et al., we employ the all-to-all
propagator with 200 low eigenmodes as well as HYP smeared link to improve the
statistical accuracy.
