On the value-distribution of the difference between logarithms of two   symmetric power $L$-functions
  We consider the value distribution of the difference between logarithms of two symmetric power $L$-functions at $s=\sigma > 1/2$. We prove that certain averages of those values can be written as integrals involving a density function which is constructed explicitly. 
Kohji Matsumoto and Yumiko Umegaki
math.NT