Mellin transform of the modular discriminant
= Mellin transform of the modular discriminant
For every real $s$, the rapidly convergent integral
$$
\int_0^\infty\Delta(it)t^{s-1}\,dt
$$
is the analytic continuation of $(2\pi)^{-s}\Gamma(s)L(\Delta,s)$. The product for $\Delta$ makes the integrand positive, so $L(\Delta,s)>0$ for real $s>0$.