arXiv subjects

S. Zelditch

Publications and source records attributed to S. Zelditch.

13 recordsLinked to original sources

arXiv2017

Sup norms of Cauchy data of eigenfunctions on manifolds with concave boundary

We prove that the Cauchy data of Dirichlet or Neumann $Δ$- eigenfunctions of Riemannian manifolds with concave (diffractive) boundary can only achieve maximal sup norm bounds if there exists a self-focal point on the boundary, i.e. a point at which a positive measure of geodesics leaving the point return to the point. As an application, the Dirichlet or Neumann eigenfunctions of Riemannian manifolds with concave boundary and non-positive curvature never have eigenfunctions whose boundary traces achieve maximal sup norm bounds.

math.AP↗

arXiv2012

Eigenfunctions and Nodal Sets

This is a survey of recent results on eigenfunctions of the Laplacian on compact Riemannian manifolds and their nodal sets. It is the write-up of my talk at JDG 2011.

math.SP↗

arXiv2012

Quantum ergodic restriction theorems, II: manifolds without boundary

We prove that if $(M, g)$ is a compact Riemannian manifold with ergodic geodesic flow, and if $H \subset M$ is a smooth hypersurface satisfying a generic asymmetry condition with respect to the geodesic flow, then restrictions $ϕ_j |_H$ of an orthonormal basis $\{ϕ_j\}$ of $Δ$-eigenfunctions of $(M, g)$ to $H$ are quantum ergodic on $H$. The condition on $H$ is satisfied by geodesic circles, closed horocycles and generic closed geodesics on a hyperbolic surface.

math.SP↗

arXiv2011

Large deviations of empirical measures of zeros on Riemann surfaces

This is a continuation of a project on large deviations for the empirical measures of zeros of random holomorphic sections of random line bundles over a Riemann surface X. In a previous article with O. Zeitouni (arXiv:0904.4271), we proved an LDP for random polynomials in the genus zero case. In higher genus, there is a Picard variety of line bundles and so the line bundle L is a random variable as well as the section s. The space of pairs (L, s) is known as the "vortex moduli space". The zeros of (L, s) fill out the configuration space $X^{(N)}$ of $N$ points of $X$. The LDP shows that the configurations concentrate at one equilibrium measure exponentially fast. The new features of the proof involve Abel-Jacobi theory, the prime form and bosonization.

math.PR↗

arXiv2010

Addendum to "Energies of zeros of random sections on Riemann surfaces" [arXiv:0705.2000]. Indiana Univ. Math. J. 57 (2008), no. 4, 1753-1780

This is an addendum to the article of Qi Zhong cited above [arXiv:0705.2000]. It outlines how to apply the main result of that article to calculate the asymptotics of the expected energy of zeros of random polynomials on the Riemann sphere $S^2$ with respect to the log chordal distance $\log [z, w]$. The cited article did not calculate the asymptotic energy this way, but by an ad-hoc method, and the calculation contained some errors. The correct calculation here agrees (up to the stipulted remainder) with that of Armentano- Beltran-Shub.

math.PR↗

arXiv2009

Recent developments in mathematical Quantum Chaos

This is a survey of recent results on quantum ergodicity, specifically on the large energy limits of matrix elements relative to eigenfunctions of the Laplacian. It is mainly devoted to QUE (quantum unique ergodicity) results, i.e. results on the possible existence of a sparse subsequence of eigenfunctions with anomalous concentration. We cover the lower bounds on entropies of quantum limit measures due to Anantharaman, Nonnenmacher, and Rivière on compact Riemannian manifolds with Anosov flow. These lower bounds give new constraints on the possible quantum limits. We also cover the non-QUE result of Hassell in the case of the Bunimovich stadium. We include some discussion of Hecke eigenfunctions and recent results of Soundararajan completing Lindenstrauss' QUE result, in the context of matrix elements for Fourier integral operators. Finally, in answer to the potential question `why study matrix elements' it presents an application of the author to the geometry of nodal sets.

math.AP↗

arXiv2009

Large deviations of empirical zero point measures on Riemann surfaces, I: $g = 0$

We prove an LDP for the empirical measure of complex zeros of a Gaussian random complex polynomial of degree N of one variable as N tends to infinity. The Gaussian measure is induced by an inner product defined by a smooth weight (Hermitian metric) $h$ and a Bernstein-Markov measure $ν$. The speed is N^2 and the the unique minimizer of the rate function $I$ is the weighted equilibrium measure $ν_{h, K}$ with respect to $h$ on the support $K$ of $ν$.

math.PR↗

arXiv2006

Counting String Vacua

This article reviews recent work with M.R.Douglas and B. Shiffman on statistics of vacua in type IIb flux compactions of string/M theory.

math-ph↗

arXiv2003

Counter-example to conjectured SU(N) character asymptotics

We give a counterexample to the large $N$ asymptotics of character values $χ_R(U)$ of irreducible characters of SU(N) conjectured in papers of Gross-Matytsin and Kazakov-Wynter in 1995. Our counterexample is based on Kostant's calculation of values of SU(N) characters on Coxeter elements.

hep-th↗

arXiv2003

Random polynomials of high degree and Levy concentration of measure

We show that the L^p norms of random sequences {s_N} of L^2 normalized holomorphic sections of increasing powers of an ample line bundle on a compact Kahler manifold are almost surely bounded for 2<p< infinity, and are almost surely O((log N)^{1/2}) for p= infinity. This estimate also holds for almost-holomorphic sections of positive line bundles on symplectic manifolds (in the sense of math.SG/0212180) and we give almost sure bounds for the C^k norms. Our methods involve asymptotics of Bergman-Szego kernels and the concentration of measure phenomenon.

math.CV↗

arXiv2003

Harmonic Analysis on Toric Varieties

Harmonic analysis on a toric Kahler variety M refers to the orthonormal basis of eigenfunctions of the complex torus action on the spaces H^0(M, L^N) of holomorphic sections of powers of a positive line bundle L and the Fourier multipliers that act on them. Using this harmonic analysis, we give an exact formula for the Szego kernel as a Fourier multiplier applied to the pull back of the Szego kernel of projective space under a monomial embedding. The Fourier multiplier involves a partition function of the convex lattice polytope P associated to M. We further prove that this Fourier multiplier is a Toeplitz operator, and as a corollary we obtain an oscillatory integral formula for the characters χ_{NP} of the torus action on H^0(M, L^N).

math.CV↗

arXiv2002

Asymptotics of almost holomorphic sections on symplectic manifolds

We study the asymptotics of almost holomorphic sections $s \in H^0_J(M, ω)$ of an ample line bundle $L \to M$ over an almost complex symplectic manifold in the sense of Boutet de Monvel-Guillemin. Such sections are defined as the kernel of a complex which is analogous to the $\bar{\partial}$ complex for a positive line bundle over a complex manifold. Our main result is the scaling limit asymptotics of the Szego projectors $Π_N$ of powers $L^N$. The Kodaira embedding theorem and Tian almost isometry theorem are almost immediate consequences of the scaling limit. We also relate such almost holomorphic sections to the asymptotically holomorphic sections in the sense of Donaldson and Auroux.

math.SG↗

arXiv2002

Asymptotics of almost holomorphic sections of ample line bundles on symplectic manifolds: an addendum

We define a Gaussian measure on the space $H^0_J(M, L^N)$ of almost holomorphic sections of powers of an ample line bundle $L$ over a symplectic manifold $(M, ω)$, and calculate the joint probability densities of sections taking prescribed values and covariant derivatives at a finite number of points. We prove that they have a universal scaling limit as $N \to \infty$. This result completes our proof (with P. Bleher) that correlations between zeros of sections in the almost-holomorphic setting have the same universal scaling limit as in the complex case (see Universality and scaling of zeros on symplectic manifolds, Random matrix models and their applications, 31--69, Math. Sci. Res. Inst. Publ., 40)

math.SG↗