IV.D311 — Chowla--Selberg decomposition

The Chowla-Selberg decomposition separates Z(s; iy) = T_1(s) + T_2(s,y) + T_3(s,y) into pure Riemann zeta T_1 = 2*zeta(2s), a leading power-law term T_2 proportional to y^{1-2s}, and exponentially suppressed corrections T_3 involving modified Bessel functions.