Lemniscate Convexity and Other Properties of Generalized Bessel Functions

Abstract

Sufficient conditions on associated parameters $p,b$ and $c$ are obtained so that the generalized and \textquotedblleft{normalized}\textquotedblright{} Bessel function $u_p(z)=u_{p,b,c}(z)$ satisfies $|(1+(zu''_p(z)/u'_p(z)))^2-1|<1$ or $|((zu_p(z))'/u_p(z))^2-1|<1$. We also determine the condition on these parameters so that $-(4(p+(b+1)/2)/c)u'_p(z)\prec\sqrt{1+z}$. Relations between the parameters $\mu$ and $p$ are obtained such that the normalized Lommel function of first kind $h_{\mu,p}(z)$ satisfies the subordination $1+(zh''_{\mu,p}(z)/h'_{\mu,p}(z))\prec\sqrt{1+z}$. Moreover, the properties of Alexander transform of the function $h_{\mu,p}(z) $ are discussed.