arXiv subjects
Publications and source records attributed to Oswaldo Velásquez Castañón.
In this paper, we review the study of the distribution of the zeros of certain approximations for the Ramanujan $Ξ-$function given by Haseo Ki, and we provide a new proof of his results. Our approach is motivated by the ideas of Velásquez in the study of the zeros of certain sums of entire functions with some condition of stability related to the Hermite-Biehler theorem.
The greatest lower bound of the real parts of the roots of a partial sum of the Dirichlet series of Riemann's zeta function is asymptotically equivalent to the opposite of the number of terms of this sum, multiplied by the Napierian logarithm of 2, when this number of terms tends to infinity.
We study the distribution of the zeros of functions of the form $f(s)=h(s) \pm h(2a-s)$, where $h(s)$ is a meromorphic function, real on the real line, $a$ a real number. One of our results establishes sufficient conditions under which all but finitely many of the zeros of $f(s)$ lie on the line $\Re s = a$, called the {\it critical line} for the function $f(s)$, and be simple, given that all but finitely many of the zeros of $h(s)$ lie on the half-plane $\Re s < a$. This results can be regarded as a generalization of the necessary condition of stability for the function $h(s)$, in the Hermite-Biehler theorem. We apply this results to the study of translations of the Riemann Zeta Function and $L$ functions, and integrals of Eisenstein Series, among others.