Chiral logs with staggered fermions

We compute chiral logarithms in the presence of "taste" symmetry breaking of staggered fermions. The lagrangian of Lee and Sharpe is generalized and then used to calculate the logs in π and K masses. We correct an error in Ref. [1]; the issue turns out to have implications for the comparison with simulations, even at tree level. MILC data with three light dynamical flavors can be well fit by our formulas. However, two new chiral parameters, which describe O(a2) hairpin diagrams for taste-nonsinglet mesons, enter in the fits. To obtain precise results for the physical O(p4) coefficients, these new parameters will need to be bounded, at least roughly.