Critical edge behavior in the perturbed Laguerre ensemble and the Painleve V transcendent

Abstract

In this paper, we consider the perturbed Laguerre unitary ensemble described by the weight function of $$w(x,t)=(x+t)^λx^αe^{-x}$$ with $ x\geq 0,\ t>0,\ α>0,\ α+λ+1 > 0.$ The Deift-Zhou nonlinear steepest descent approach is used to analyze the limit of the eigenvalue correlation kernel. It was found that under the double scaling $s=4nt,$ $n\to \infty,$ $t\to 0 $ such that $s$ is positive and finite, at the hard edge, the limiting kernel can be described by the $φ$-function related to a third-order nonlinear differential equation, which is equivalent to a particular Painlevé V (shorted as P$_{\rm V}$) transcendent via a simple transformation. Moreover, this P$_{\rm V}$ transcendent is equivalent to a general Painlevé P$_{\rm III}$ transcendent. For large $s,$ the P$_{\rm V}$ kernel reduces to the Bessel kernel $\mathbf{J}_{α+λ}.$ For small $s,$ the P$_{\rm V}$ kernel reduces to another Bessel kernel $\mathbf{J}_α.$ At the soft edge, the limiting kernel is the Airy kernel as the classical Laguerre weight.

53 pages