## Asymptotics of the partition function for random matrices via Riemann-Hilbert techniques and applications to graphical enumeration.(English)Zbl 1140.82307

The authors establish three new theorems (Theorems 1.1, 1.3, 1.4) on asymptotics for the following family of integrals $Z_N(t_1,t_2,\dots, t_\nu)\overset{\text{def}} =\int\dots\int\exp\left\{-N^2\left [\frac 1N\sum^N_{i =1}v(\lambda_j;t_1,\dots, t_\nu)-\frac{1}{N^2}\sum_{j\neq\ell}\log |\lambda_j-\lambda_l|\right ] \right\}\,d^N\lambda,$ where $V(\lambda;t_1,\dots, t_\nu)\overset{\text{def}}=\tfrac 12\lambda^2+ \sum^\nu_{k=1} t_k\lambda^k,$ and $$t_1,\dots,t_\nu$$ are parameters.
Theorem 1.1 is related to the expansion $$\log\left(\frac{Z_N(t)}{Z_N(0)}\right)=N^2e_0(t)+e_1 (t)+\frac {1}{N^2}e_2(t)+\dots$$ for $$t\in\mathbb R^\nu$$ with $$|t|\leq T$$, $$t_\nu>\gamma \sum^{\nu-1}_{j=1}| t_j|$$.
Theorem 1.3 is related to the calculation of $$e_g(t)$$ via $$g$$-maps.
Theorem 1.4 is a technical tool relating $$Z_N(t)$$ to statistical mechanics and orthogonal polynomials theory.

### MSC:

 82B44 Disordered systems (random Ising models, random Schrödinger operators, etc.) in equilibrium statistical mechanics 47B80 Random linear operators 47A56 Functions whose values are linear operators (operator- and matrix-valued functions, etc., including analytic and meromorphic ones) 42C05 Orthogonal functions and polynomials, general theory of nontrigonometric harmonic analysis 15B52 Random matrices (algebraic aspects) 30E25 Boundary value problems in the complex plane 33D45 Basic orthogonal polynomials and functions (Askey-Wilson polynomials, etc.)

Zbl 0453.05035
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