The zeros of determinants of matrix-valued polynomials that are orthonormal on a semi-infinite or finite interval

Let the sequence of matrix-valued polynomials $(P_j)_{j=0}^{\infty }$ be orthonormal with respect to a nonnegative matrix-valued measure $\sigma $. Assuming that, for some $\alpha,\beta \in \mathbb{R}$, the support of $\sigma $ is contained in the closed set $[\alpha, +\infty)$, $(-\infty, \beta]$ or $[\alpha,\beta]$, the zeros of the polynomials $(\det P_j)_{j=0}^{\infty }$ are shown to lie in the open set $(\alpha, +\infty)$, $(-\infty, \beta)$ or $(\alpha,\beta)$, respectively.v
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