Special functions, integral equations and a Riemann-Hilbert problem

Abstract:

We consider a pair of special functions, $u_\beta$ and $v_\beta$, defined respectively as the solutions to the integral equations \begin{equation*} u(x)=1+\int ^\infty _0 \frac {K(t) u(t) dt}{t+x} ~~\mbox {and}~~v(x)=1-\int ^\infty _0 \frac { K(t) v(t) dt}{t+x},~~x\in [0, \infty ),\end{equation*} where $K(t)= \frac {1} \pi \exp \left (- t^\beta \sin \frac {\pi \beta } 2\right )\sin \left ( t^\beta \cos \frac {\pi \beta } 2 \right )$ for $\beta \in (0, 1)$. In this note, we establish the existence and uniqueness of $u_\beta$ and $v_\beta$ which are bounded and continuous in $[0, +\infty )$. Also, we show that a solution to a model Riemann-Hilbert problem in Kriecherbauer and McLaughlin [Int.Math.Res.Not.,1999] can be constructed explicitly in terms of these functions. A preliminary asymptotic study is carried out on the Stokes phenomena of these functions by making use of their connection formulas.

Several open questions are also proposed for a thorough investigation of the analytic and asymptotic properties of the functions $u_\beta$ and $v_\beta$, and a related new special function $G_\beta$.