  The B-meson wavefunction has been studied with the help of the
vacuum-to-meson matrix element of the nonlocal operators in the heavy quark
effective theory. In order to obtain the Wandzura-Wilczek-type B-meson
wavefunction, we solve the equations which are derived from the equation of
motion of the light spectator quark in the B meson by using two different
assumptions. Under the condition that $\omega_0=2\bar{\Lambda}$, the solutions
for the B-meson wavefunction in this paper agree well with the one obtained by
directly taking the heavy quark limit $m_b\to\infty$. Our results show that the
equation of motion of the light spectator quark in the B meson can impose a
strong constraint on the B-meson wavefunctions $\Psi_\pm(\omega,z^2)$. Based on
the obtained results, we claim that both its distribution amplitudes
$\phi_B(\omega)$ and $\bar\phi_B(\omega)$ are important for calculating the B
meson decays.

High Energy Physics - Phenomenology