Pointwise character bound extension to spherical functions on compact symmetric spaces

Let XX be an irreducible symmetric space of compact type, with spectral parameter μΛ+it\mu\in \Lambda^+\subset i\mathfrak{t}^* and spatial parameter HtH\in\mathfrak{t}. Let ψ(μ,H)\psi(\mu,H) be the spherical function normalized by ψ(μ,0)=1\psi(\mu,0)=1. Let WW be the Weyl group, and let Φ+\Phi^+ be the positive restricted root system, with root multiplicities m(α)Z1m(\alpha)\in\mathbb{Z}_{\geq 1}. Spherical-function pointwise bound. There exists a uniform constant C>0C>0 such that

ψ(μ,H)CsWαΦ+(1+sμ,αsin(iα(H)))m(α)2.|\psi(\mu, H)|\leq C\sum_{s\in W}\prod_{\alpha\in\Phi^+}\left(1+ \left|\langle s\mu,\alpha\rangle\sin\left(i\alpha( H)\right)\right|\right)^{-\frac{m(\alpha)}{2}}.

The inequality is proposed as a natural extension of the pointwise character bound for SU(3)\mathrm{SU}(3) to spherical functions on compact symmetric spaces. Its resolution is not specified in the supplied text.

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Primary source

Yunfeng Zhang, “Pointwise character bounds for SU(3)”, arXiv:2604.17589 (2026).

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