Geometric analysis of a class of harmonic mappings defined by a differential inequality

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Hauptverfasser: Allu, Vasudevarao, Biswas, Raju, Mandal, Rajib
Format: Preprint
Veröffentlicht: 2025
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author Allu, Vasudevarao
Biswas, Raju
Mandal, Rajib
author_facet Allu, Vasudevarao
Biswas, Raju
Mandal, Rajib
contents In this paper, we introduces and undertake as a systematical investigation of the class $\mathcal{P}_{\mathcal{H}}^{0}(α,M)$ of normalized harmonic mappings $f = h + \overline{g}$ in the unit disk $\mathbb{D}$, defined by the differential inequality \[ \text{Re}\left((1-α)h'(z) + αz h''(z)\right) > -M + \left|(1-α)g'(z) + αz g''(z)\right|\quad\text{for}\quad z\in\Bbb{D}, \] where $M > 0$, $α\in (0,1]$, and $g'(0) = 0$. This class extends the harmonic analogue of functions with positive real part and offers a unified framework for analyzing their geometric characteristics. We obtain sharp coefficient bounds for both the analytic and co-analytic parts, establish sharp growth bounds, and determine the radii of univalency, starlikeness, and convexity. Furthermore, we show that $\mathcal{P}_{\mathcal{H}}^{0}(α,M)$ is closed under convex combinations, and under suitable restrictions on the parameters, it is also closed under convolution. Our findings generalize and extend several known results in the theory of harmonic mappings.
format Preprint
id arxiv_https___arxiv_org_abs_2501_01663
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Geometric analysis of a class of harmonic mappings defined by a differential inequality
Allu, Vasudevarao
Biswas, Raju
Mandal, Rajib
Complex Variables
30C45, 30C50, 30C80, 31A05
In this paper, we introduces and undertake as a systematical investigation of the class $\mathcal{P}_{\mathcal{H}}^{0}(α,M)$ of normalized harmonic mappings $f = h + \overline{g}$ in the unit disk $\mathbb{D}$, defined by the differential inequality \[ \text{Re}\left((1-α)h'(z) + αz h''(z)\right) > -M + \left|(1-α)g'(z) + αz g''(z)\right|\quad\text{for}\quad z\in\Bbb{D}, \] where $M > 0$, $α\in (0,1]$, and $g'(0) = 0$. This class extends the harmonic analogue of functions with positive real part and offers a unified framework for analyzing their geometric characteristics. We obtain sharp coefficient bounds for both the analytic and co-analytic parts, establish sharp growth bounds, and determine the radii of univalency, starlikeness, and convexity. Furthermore, we show that $\mathcal{P}_{\mathcal{H}}^{0}(α,M)$ is closed under convex combinations, and under suitable restrictions on the parameters, it is also closed under convolution. Our findings generalize and extend several known results in the theory of harmonic mappings.
title Geometric analysis of a class of harmonic mappings defined by a differential inequality
topic Complex Variables
30C45, 30C50, 30C80, 31A05
url https://arxiv.org/abs/2501.01663