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The Kroll-Lee-Zumino renormalizable Abelian quantum field theory of pions anda massive rho-meson is used to calculate the scalar radius of the pion at nextto leading (one loop) order in perturbation theory. Due to renormalizability,this determination involves no free parameters. The result is $<r^2_\pi>_s =0.40 {fm}^2$. This value gives for $\bar{\ell}_4$, the low energy constant ofchiral perturbation theory, $\bar{\ell}_4 = 3.4$, and $F_\pi/F = 1.05$, where Fis the pion decay constant in the chiral limit. Given the level of accuracy inthe masses and the $\rho\pi\pi$ coupling, the only sizable uncertainty in thisresult is due to the (uncalculated) NNLO contribution.

Scalar radius of the pion in the Kroll-Lee-Zumino renormalizable theory