In this paper, we address a class of problems in unitary ensembles. Specifically, we study the probability that a gap symmetric about 0, i.e. (−a, a) is found in the Gaussian unitary ensembles (GUE) and the Jacobi unitary ensembles (JUE) (where in the JUE, we take the parameters α = β). By exploiting the even parity of the weight, a doubling of the interval to (a 2 , ∞) for the GUE, and (a 2 , 1), for the (symmetric) JUE, shows that the gap probabilities maybe determined as the product of the smallest eigenvalue distributions of the LUE with parameter α = −1/2, and α = 1/2 and the (shifted) JUE with weights x 1/2 (1 − x) β andThe σ function, namely, the derivative of the log of the smallest eigenvalue distributions of the finite-n LUE or the JUE, satisfies the Jimbo-Miwa-Okamoto σ form of P V and P V I , although in the shift Jacobi case, with the weight x α (1 − x) β , the β parameter does not show up in the equation. We also obtain the asymptotic expansions for the smallest eigenvalue distributions * lvshulin1989@163.com † yangbrookchen@yahoo.co.uk ‡ Corresponding author and faneg@fudan.edu.cn of the Laguerre unitary and Jacobi unitary ensembles after appropriate double scalings, and obtained the constants in the asymptotic expansion of the gap probablities, expressed in term of the Barnes G− function valuated at special point.
IntroductionIn the work of Adler and Van Moerbeke [1], the largest eigenvalue distribution of ensembles of n × n random matrices generated by Gaussian, Laguerre and Jacobi weights for general values of the symmetry parameter β, (not to be confused with the β parameter in the Jacobi weight), has been systematically studied, from the perspective of differential operators involving multiple time variables.The gap probabilities that are studied in this paper, the unitary case, denoted by P(a, n), are represented as Fredholm determinant of an integral operator, from the early papers of Mehta, Gaudin and Dyson [19], [20], [22], [31], and [32]. In [28], the gap probability, where a union of disjoint intervals is free of eigenvalues, the integral operator has the sine kernel K(x, y) := sin(x−y) π(x−y) . The (multiple-) gap probability itself was obtained in an expansion in terms of the resolvent of the integral equation. In a tour de force computations, JMMS showed that in the single interval case where (−b, b) is free of eigenvalues, the quantity σ(τ ) := τ d dτ logdet(I − K (−b,b) ), τ = 2b, satisfies a second order non-linear differential equation. Tracy and Widom [36] studied, the finite n version of such problems, namely, the distribution of the smallest eigenvalue in the Laguerre unitary ensembles, and the largest eigenvalue distribution of the Gaussian unitary ensembles starting from the Christoffel-Darboux or Reproducing Kernel, constructed out of the "natural" orthogonal polynomials, namely the Laguerre and Hermite polynomials, respectively. Through a series of differentiation formulas, Tracy and Widom found the finite n version of the differential equations satisfied by the resolvent a...