English

Bohr radius for subordination and $K$-quasiconformal harmonic mappings

Complex Variables 2019-05-27 v1

Abstract

The present article concerns the Bohr radius for KK-quasiconformal sense-preserving harmonic mappings f=h+gf=h+\overline{g} in the unit disk D\mathbb{D} for which the analytic part hh is subordinated to some analytic function φ\varphi, and the purpose is to look into two cases: when φ\varphi is convex, or a general univalent function in \ID\ID. The results state that if h(z)=n=0anznh(z) =\sum_{n=0}^{\infty}a_n z^n and g(z)=n=1bnzng(z)=\sum_{n=1}^{\infty}b_n z^n, then \sum_{n=1}^{\infty}(|a_n|+|b_n|)r^n\leq \dist (\varphi(0),\partial\varphi(\ID)) ~\mbox{ for $r\leq r^*$} and give estimates for the largest possible rr^* depending only on the geometric property of φ(\ID)\varphi (\ID) and the parameter KK. Improved versions of the theorems are given for the case when b1=0b_1 = 0 and corollaries are drawn for the case when KK\rightarrow \infty.

Keywords

Cite

@article{arxiv.1905.10334,
  title  = {Bohr radius for subordination and $K$-quasiconformal harmonic mappings},
  author = {ZhiHong Liu and Saminathan Ponnusamy},
  journal= {arXiv preprint arXiv:1905.10334},
  year   = {2019}
}

Comments

15 pages; To appear in Bulletin of the Malaysian Mathematical Sciences Society