Exact solution to ideal chain with fixed angular momentum.

The statistical mechanics of a noninteracting polymer chain in the limit of a large number of monomers is considered when the total angular momentum L is fixed. The radius of gyration for a ring polymer in this situation is derived exactly in closed form by functional integration techniques. Even when L=0 the radius of gyration differs from that of a random walk by a prefactor of order unity. The dependence on L is discussed qualitatively and the large- L limit can be understood by physical arguments, which can also be extended to self-avoiding chains.