  In this work we prove that an entire function $f(z)$ has only negative zeros
if and only if its order is strictly less $1$, its root sequence is real-part
dominating and there exists an nonnegative integer $m$ the real function
$\left(-\frac{1}{x}\right)^{m}\frac{d^{k}}{dx^{k}}\left(x^{k+m}\frac{d^{m}}{dx^{m}}\left(\frac{f'(x)}{f(x)}\right)\right)$
are completely monotonic on $(0,\infty)$ for all nonnegative integer $k$. As an
application we state a necessary and sufficient condition for the Riemann
hypothesis and generalized Riemann hypothesis for a primitive Dirichlet
character.
