On the Laurent series expansions of the Barnes double zeta function

Abstract

We investigate the Laurent series expansions of the Barnes double zeta function ${\zeta }_2(s,\alpha ;v,w)$ at $s=1$ and $s=2$. We derive explicit limit representations for the Laurent coefficients, which may be regarded as analogues of the Euler--Stieltjes constants in the Barnes setting. In particular, we obtain formulas in terms of finite double sums with explicit correction terms, including a new limit representation for the constant term at $s=1$. We also establish relations between the Laurent coefficients at $s=1$ and the Taylor coefficients at $s=0$, as well as relations between the coefficients at $s=1$ and $s=2$. Furthermore, we study the asymptotic behavior of these coefficients as the order tends to infinity and show that they approach simple closed-form expressions with exponentially decaying error terms. Finally, we investigate arithmetic properties of certain constant terms in the Laurent expansions. We establish transcendence results for some infinite families of special values, including a family at $s=1$ for which every member is transcendental and a family at $s=2$ for which all but at most one are transcendental.

20 pages