Calculation of 1/m²_(b) corrections to <Λ_(b)(v,s)|bar{b}γ^(λ)γ₅b|Λ_(b)(v,s)> for polarized Λ_(b) in the Bethe-Salpeter equation approach

The heavy baryon \Lambda_{Q} (Q=b or c) can be regarded as composed of a heavy quark and a scalar light diquark which has good spin and isospin quantum numbers. In this picture we establish the Bethe-Salpeter (BS) equation for \Lambda_{Q} to second order in the 1/m_{Q} expansion. With the kernel containing both the scalar confinement and the one-gluon-exchange terms we solve the BS equation numerically. The value of the spin-dependant form factor for the matrix element <\Lambda_{b}{(v,s)}|\bar{b}\gamma^{\lambda}\gamma_{5}b|\Lambda_{b}(v,s)>, \epsilon_{b}, which is non-zero at order 1/m^{2}_{b}, is obtained numerically from our model.