Graduation Year

2023

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Mathematics and Statistics

Major Professor

Razvan Teodorescu, Ph.D.

Co-Major Professor

Seung-Yeop Lee, Ph.D.

Committee Member

Dmitry Khavinson, Ph.D.

Committee Member

Evguenii Rakhmanov, Ph.D.

Committee Member

Sherwin Kouchekian, Ph.D.

Committee Member

David Rabson, Ph.D.

Keywords

Random Matrix Theory, Orthogonal Polynomials, Statistical Mechanics, Riemann-Hilbert, 2D Quantum Gravity, The Ising Model

Abstract

The 2D Ising model has played an important role in the theory of phase transitions, as one of only ahandful of exactly solvable models in statistical mechanics. The original model, introduced in the 1920s, has a rich mathematical structure. It thus came as a pleasant surprise when physicists studying matrix models of 2D gravity found that, coupled to quantum gravity, the planar Ising model still had an elegant solution. The methods used by V. Kazakov and his collaborators involved the method of orthogonal polynomials. However, these methods were formal, and no direct analytic derivation of the phase transition has been described in the literature since the original paper of V. Kazakov in 1986. In this work, we present a rigorous proof of Kazakov’s results, using steepest descent analysis for biorthogonal polynomials. We are able to calculate the genus 0 partition function, and we also find that the phase transition is described by the string equation of a 3rd order reduction of the KP hierarchy, in agreement with the predictions of G. Moore, M. Douglas, and their collaborators. This is part of a forthcoming paper with Maurice Duits and Seung-Yeop Lee.

Included in

Mathematics Commons

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