Abstract
The tunneling passage of a microparticle with a spin through a three-dimensional delta potential embedded in a quantum wire with a characteristic effect of dimensional quantization is considered. This effect results in multichannel scattering, which does not occur in one-dimensional problems. The particle is also affected by a magnetic field directed along the wire which generally takes unequal constant values on both sides of the barrier. Analytical expressions for the scattering coefficients and the spin polarization coefficient of multichannel scattering are obtained. Several special cases of the obtained formulas are considered. The dependences of the mentioned coefficients on the particle energy, the parameters of the potential barrier and nanotube, and the magnetic field are investigated in a single-channel approximation in detail.