Semiflexible polymer on an anisotropic Bethe lattice

The mean square end-to-end distance of a N-step polymer on a Bethe lattice is calculated. We consider semiflexible polymers placed on isotropic and anisotropic lattices. The distance on the Cayley tree is defined by embedding the tree on a sufficiently high dimensional Euclidean space considering that every bend of the polymer defines a direction orthogonal to all the previous ones. In the isotropic case, the result obtained for the mean square end-to-end distance turns out to be identical to the one obtained for ideal chains without immediate returns on an hypercubic lattice with the same coordination number of the Bethe lattice. For the general case, we obtain the asymptotic behavior in the semiflexible and also in the almost rigid limits.