Scalar products in models with GL(3) trigonometric R-matrix. Highest coefficient

Abstract

We study quantum integrable models with GL(3) trigonometric R-matrix solvable by the nested algebraic Bethe ansatz. Scalar products of Bethe vectors in such models can be expressed in terms of a bilinear combination of the highest coefficients. We show that in the models with GL(3) trigonometric R-matrix there exist two different highest coefficients. We obtain various representations for them in terms of sums over partitions. We also prove several important properties of the highest coefficients, which are necessary for the evaluation of the scalar products.