ON q-ANALOGUES OF ZETA FUNCTIONS OF ROOT SYSTEMS

. Komori, Matsumoto and Tsumura introduced a zeta function ζ r ( s , (cid:49)) associated with a root system (cid:49) . In this paper, we introduce a q -analogue of this zeta function, denoted by ζ r ( s , a , (cid:49) ; q ) , and investigate its properties. We show that a ‘Weyl group symmetric’ linear combination of ζ r ( s , a , (cid:49) ; q ) can be written as a multiple integral over a torus involving functions ψ s . For positive integers k , functions ψ k can be regarded as q -analogues of the periodic Bernoulli polynomials. When (cid:49) is of type A 2 or A 3 , the linear combinations can be expressed as the functions ψ k , which are q -analogues of explicit expressions of Witten’s volume formula. We also introduce a two-parameter deformation of the zeta function ζ r ( s , (cid:49)) and study its properties. ,