Coefficient Problems and Sharp Determinant Estimates for the Class
arXiv:2607.25280
The paper derives sharp bounds for logarithmic and inverse logarithmic coefficients, as well as second-order Hankel and Hermitian‑Toeplitz determinants, for a subclass of normalized analytic functions defined by specific subordination conditions.
Abstract
In this paper, we investigate coefficient-related problems for a subclass of normalized analytic functions \(\mathcal{S}^*_{q_1}\), defined by the subordination conditions \[ \frac{f'(z)}{q_1(z)} \prec 1+\sin z \quad \text{and} \quad q_1(z) \prec e^z,\qquad z\in\mathbb{D}. \] Sharp bounds are obtained for the logarithmic and inverse logarithmic coefficients, as well as for their absolute differences. Moreover, sharp estimates are derived for the second-order Hankel and Hermitian--Toeplitz determinants associated with these coefficients. These results extend and refine several known bounds for related subclasses of analytic functions.