The Kosterlitz-Thouless transition in the XY Kagom\'{e} antiferromagnet

The problem of the Kosterlitz-Thouless (KT) transition in the highly frustrated XY Kagom\'{e} antiferromagnet is solved. The problem is mapped onto that of the KT transition in the XY ferromagnet on the hexagonal lattice. The transition temperature is found. It is shown that the spin correlation function exponentially decays with distance even in the low-temperature phase, in contrast to the order parameter correlation function, which decays algebraically with distance.