Abstract

We prove that when suitably normalized, small enough powers of the absolute value of the characteristic polynomial of random Hermitian matrices, drawn from one-cut regular unitary invariant ensembles, converge in law to Gaussian multiplicative chaos measures. We prove this in the so-called L^2-phase of multiplicative chaos. Our main tools are asymptotics of Hankel determinants with Fisher–Hartwig singularities. Using Riemann–Hilbert methods, we prove a rather general Fisher–Hartwig formula for one-cut regular unitary invariant ensembles.

Highlights

  • 1.1 Main resultLog-correlated Gaussian fields, namely Gaussian random generalized functions whose covariance kernels have a logarithmic singularity on the diagonal, are known to show up in various models of modern probability and mathematical physics—e.g. in combinatorial models describing random partitions of integers [35], random matrix theory [31,34,60], lattice models of statistical mechanics [41], the construction of conformally invariant random planar curves such as stochastic Loewner evolution [4,63], and growth models [9] just to name a few examples

  • While our results do not extend to the full range of values of β where one expects the result to be valid, we believe that an appropriate modification of the methods of this paper eventually will yield the result in its full generality

  • One could consider the behavior of the characteristic polynomial in a microscopic neighborhood of a fixed point, where one might expect it to be asymptotically a random analytic function as it is for the CUE—see [13], or one could consider the logarithm of the absolute value of the characteristic polynomial on a macroscopic scale inside or outside the support of the equilibrium measure

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Summary

Main result

Log-correlated Gaussian fields, namely Gaussian random generalized functions whose covariance kernels have a logarithmic singularity on the diagonal, are known to show up in various models of modern probability and mathematical physics—e.g. in combinatorial models describing random partitions of integers [35], random matrix theory [31,34,60], lattice models of statistical mechanics [41], the construction of conformally invariant random planar curves such as stochastic Loewner evolution [4,63], and growth models [9] just to name a few examples. A fundamental tool in describing these geometric properties of the fields is a class of random measures, which can be formally written as an exponential of the field As these fields are distributions instead of functions, exponentiation is not an operation one can naively perform, but through a suitable limiting and normalization procedure, these random measures can be rigorously constructed and they are known as Gaussian multiplicative chaos measures. For a large class of models of random matrix theory, the following is true: when the size of the matrix tends to infinity, the logarithm of the characteristic polynomial behaves like a log-correlated field This is essentially equivalent to a suitable central limit theorem for the global linear statistics of the random matrix—see [31,34,60] for results concerning the GUE, Haar distributed random unitary matrices, and the complex Ginibre ensemble. This settles some conjectures due to Forrester and Frankel—see Remark 2.11 and [28, Conjecture 5 and Conjecture 8] for further information about their conjectures

Motivations and related results
Organisation of the paper
One-cut regular ensembles of random Hermitian matrices
The characteristic polynomial and powers of its absolute value
Gaussian multiplicative chaos
Outline of the proof
Hankel determinants and Riemann–Hilbert problems
Hankel determinants and orthogonal polynomials
Riemann–Hilbert problems and orthogonal polynomials
Differential identities
Solving the Riemann–Hilbert problem
Transforming the Riemann–Hilbert problem
The first transformation
The second transformation
The global parametrix
Local parametrices near the singularities
Local parametrices at the edge of the spectrum
The final transformation and asymptotic analysis of the problem
Integrating the differential identities
Full Text
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