Highest weight representations of $U_q(\widehat{sl}(2\mathrm{\mid }1))$ and correlation functions of the q-deformed supersymmetric t-J model

We re-examine the level-one irreducible highest weight representations of the quantum affine superalgebra $U_q(\widehat{sl}(2\mathrm{\mid }1))$ and derive the characters and supercharacters associated with these representations. We calculate the exchange relations of the vertex operators and find that these vertex operators satisfy the graded Faddeev-Zamolodchikov algebra. We give an integral expression of the correlation functions of the q-deformed supersymmetric t-J model and derive the difference equations which they satisfy.