arXiv subjects

E. Basor

Publications and source records attributed to E. Basor.

4 recordsLinked to original sources

arXiv2024

A survey of asymptotics of determinants for structured matrices

In this survey we show how to produce asymptotics of determinants of structured matrices using operator theory methods. We describe the asymptotics for finite Toeplitz matrices, finite Toeplitz plus Hankel matrices and generalizations of these, and also finite sections of functions of Toeplitz operators, all with smooth matrix-valued symbols. Many of these results are well-known. However, the results for certain Toeplitz plus Hankel operators with matrix-valued symbol are presented for the first time and the result for the finite sections of functions of Toeplitz operators is new.

math.FA↗

arXiv2023

Asymptotics of block Toeplitz determinants with piecewise continuous symbols

We determine the asymptotics of the block Toeplitz determinants $\det T_n(\phi)$ as $n\to\infty$ for $N\times N$ matrix-valued piecewise continuous functions $\phi$ with a finitely many jumps under mild additional conditions. In particular, we prove that $$ \det T_n(\phi) \sim G^n n^\Omega E\quad {\rm as}\ n\to \infty, $$ where $G$, $E$, and $\Omega$ are constants that depend on the matrix symbol $\phi$ and are described in our main results. Our approach is based on a new localization theorem for Toeplitz determinants, a new method of computing the Fredholm index of Toeplitz operators with piecewise continuous matrix-valued symbols, and other operator theoretic methods. As an application of our results, we consider piecewise continuous symbols that arise in the study of entanglement entropy in quantum spin chain models.

math.FA↗

arXiv2018

Modified Szego-Widom Asymptotics for Block Toeplitz Matrices with Zero Modes

The Szego-Widom theorem provides an expression for the determinant of block Toeplitz matrices in the asymptotic limit of large matrix dimension n. We show that the presence of zero modes, i.e, eigenvalues that vanish as \alpha^n, |\alpha|<1, when n \to \infty, require a modification of the Szego-Widom theorem. A new asymptotic expression for the determinant of a certain class of block Toeplitz matrices with one pair of zero modes is derived. The result is inspired by 1-dimensional topological superconductors, and the relation with the latter systems is discussed.

math-ph↗

arXiv2004

Toeplitz Determinants From Compatibility Conditions

In this paper we show, how a straightforward and natural application of a pair of fundamental identities valid for polynomials orthogonal over the unit circle, can be used to calculate the determinant of the finite Toeplitz matrix, $$ Δ_n=\det(w_{j-k})_{j,k=0}^{n-1}:= \det(\int_{|z|=1}\frac{w(z)}{z^{j-k+1}}\frac{dz}{2πi})_{j,k=0}^{n-1}, $$ with the Fisher-Hartwig symbol, $$ w(z)=C(1-z)^{α+iβ}(1-1/z)^{α-iβ},\quad |z|=1, α>-1/2, β\in{\mathbb R} . $$ Here $C$ is the normalisation constant chosen so that $w_0=\frac{1}{2π}.$ We use the same approach to compute a difference equation for expressions related to the determinants of the symbol $$w(z) = {\rm e}^{t(z+1/z)},$$ a symbol important in the study of random permutations. Finally, we study the analogous equations for the symbol $$w(z) = {\rm e}^{tz}\prod_{α=1}^{M}(\frac{z-a_α}{z})^{g_α}.$$

math.CA↗