Baryon magnetic moments in chiral perturbation theory

We consider the chiral expansion of the octet baryon magnetic moments in heavy baryon chiral perturbation theory including all terms which are of order $q^4$. These terms are formally of quadratic order in the quark masses. We show that despite the large non-analytic quark mass corrections to the Coleman-Glashow relations at order $q^3$, including all analytic and non-analytic corrections at order $q^4$, which in total are of moderate size, allows for a fit to the measured magnetic moments due to the appearance of counter terms with free coupling constants of natural size. In this scheme, the $\Lambda \Sigma^0$ transition moment is predicted to be $\mu_{\Lambda \Sigma^0} = (1.42 \pm 0.01) \mu_N$.