What do we know about the strange magnetic radius?

We analyze the q2-dependence of the strange magnetic form factor, GM(s)(q2), using heavy baryon chiral perturbation theory (HBχPT) and dispersion relations. We find that in HBχPT a significant cancellation occurs between the O(p3) and O(p4) loop contributions. Consequently, the slope of GM(s) at the origin displays an enhanced sensitivity to an unknown O(p4) low-energy constant. Using dispersion theory, we estimate the magnitude of this constant, show that it may have a natural size, and conclude that the low-q2 behavior of GM(s) could be dominated by non-perturbative physics. We also discuss the implications for the interpretation of parity-violating electron scattering measurements used to measure GM(s)(q2).