The Brown measure of a family of free multiplicative Brownian motions
Apr 16, 202172 pages
Published in:
- Probab.Theor.Related Fields 186 (2023) 3-4, 1081-1166,
- Probab.Theor.Related Fields 186 (2023) 1081
- Published: Aug 1, 2023
e-Print:
- 2104.07859 [math.PR]
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Abstract: (Springer)
We consider a family of free multiplicative Brownian motions parametrized by a real variance parameter s and a complex covariance parameter We compute the Brown measure of where u is a unitary element freely independent of We find that has a simple structure, with a density in logarithmic coordinates that is constant in the -direction. These results generalize those of Driver–Hall–Kemp and Ho–Zhong for the case We also establish a remarkable “model deformation phenomenon,” stating that all the Brown measures with s fixed and varying are related by push-forward under a natural family of maps. Our proofs use a first-order nonlinear PDE of Hamilton–Jacobi type satisfied by the regularized log potential of the Brown measures. Although this approach is inspired by the PDE method introduced by Driver–Hall–Kemp, our methods are substantially different at both the technical and conceptual level.Note:
- Author final version. To appear in Probability Theory and Related Fields. 72 pages with 14 figures
- 46L54 Free probability and free operator algebras
- 60B20 Random matrices (probabilistic aspects)
- 35F21 Hamilton-Jacobi equations
- 58J65 Diffusion processes and stochastic analysis on manifolds
- boundary condition: unitarity
- family
- Brownian motion
- structure
- density
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