We obtain affine analogs of
the Gindikin–Karpelevich and Casselman–Shalika formulas as sums over Kashiwara
and Lusztig’s canonical bases. As suggested by these formulas, we define natural
q-deformation of arithmetical functions such as (multi)partition functions and
Ramanujan τ-functions, and prove various identities among them. In some examples
we recover classical identities by taking limits. Additionally, we consider
q-deformation of the Kostant function and study certain q-polynomials whose special
values are weight multiplicities.
Keywords
quantum affine algebras, canonical bases, q-deformation of
arithmetic functions