A relation between the zeros of different two L-functions which have the Euler product and functional equation

As automorphic $L$-functions or Artin $L$-functions, several classes of $L$-functions have Euler products and functional equations. In this paper we study the zeros of $L$-functions which have the Euler products and functional equations. We show that there exists some relation between the zeros of the Riemann zeta-function and the zeros of such $L$-functions. As a special case of our results, we find the relations between the zeros of the Riemann zeta-function and the zeros of automorphic $L$-functions attached to elliptic modular forms or the zeros of Rankin-Selberg $L$-functions attached to two elliptic modular forms.