On the order of convexity for the shifted hypergeometric functions

Abstract: In the present paper, we study the order of convexity of $z\Gauss(a,b;c;z)$ with real parameters $a, b$ and $c$ where $\Gauss(a,b;c;z)$ is the Gaussian hypergeometric function. First we obtain some conditions for $z\Gauss(a,b;c;z)$ with no any finite orders of convexity by considering its asymptotic behavior around $z=1$. Then the order of convexity of $z\Gauss(a,b;c;z)$ is demonstrated for some ranges of real parameters $a,b$ and $c$. In the last section, we give some examples as the applications of the main results.