Second Topological Moment < m^2 > of Two Closed Entangled Polymers
  We calculate the second topological moment < m^2 > of entanglement of two closed polymers $P_1$ and $P_2$ in a solution. The result holds approximately for a closed polymer linked to many others, which may be considered as a single very long effective polymer. 
F. Ferrari, H. Kleinert, I. Lazzizzera