The $m$-symmetric Macdonald polynomials

The $m$-symmetric Macdonald polynomials form a basis of the space of polynomials that are symmetric in the variables $x_{m+1},x_{m+2},\dots$ (while having no special symmetry in the variables $x_1,\dots ,x_m$).We establish in this article the fundamental properties of the $m$-symmetric Macdonald polynomials. These include among other things the orthogonality with respect to a natural scalar product, as well as formulas for the squared norm, the evaluation, and the inclusion. We also obtain a Cauchy-type identity for the $m$-symmetric Macdonald polynomials which specializes to the known Cauchy-type identity for the non-symmetric Macdonald polynomials.