Kernel Functions for Difference Operators of Ruijsenaars Type and Their   Applications
  A unified approach is given to kernel functions which intertwine Ruijsenaars difference operators of type A and of type BC. As an application of the trigonometric cases, new explicit formulas for Koornwinder polynomials attached to single columns and single rows are derived. 
Yasushi Komori, Masatoshi Noumi and Jun'ichi Shiraishi