A Path Integration Approach to the Correlators of XY Heisenberg Magnet   and Random Walks
  The path integral approach is used for the calculation of the correlation functions of the $XY$ Heisenberg chain. The obtained answers for the two-point correlators of the $XX$ magnet are of the determinantal form and are interpreted in terms of the generating functions for the random turns vicious walkers. 
N. M. Bogoliubov, C. Malyshev