BB potentials in quenched lattice QCD

The potentials between two B mesons are computed in the heavy-quark limit using quenched lattice QCD at m(pi) similar to 400 MeV. Nonzero central potentials are clearly evident in all four spin-isospin channels, (I,s(l))=(0,0), (0, 1), (1, 0), (1, 1), where s(l) is the total spin of the light degrees of freedom. At short distance, we find repulsion in the I not equal s(l) channels and attraction in the I = s(l) channels. Linear combinations of these potentials that have well-defined spin and isospin in the t-channel are found, in three of the four cases, to have substantially smaller uncertainties than the potentials defined with the s-channel (I,s(l)), and allow quenching artifacts from single hairpin exchange to be isolated. The BB*pi coupling extracted from the long-distance behavior of the finite-volume t-channel potential is found to be consistent with quenched calculations of the matrix element of the isovector axial-current. The tensor potentials in both of the s(l) = 1 channels are found to be consistent with zero within calculational uncertainties.