Leading logarithms for the nucleon mass

Within the heavy baryon chiral perturbation theory approach, we have studied the leading logarithm behavior of the nucleon mass up to four-loop order exactly and we present some results up to six-loop order as well as an all-order conjecture. The same methods allow to calculate the main logarithm multiplying the terms with fractional powers of the quark mass. We calculate thus the coefficients of m2n+1log(n−1)⁡(μ2/m2)m2n+1log(n−1)⁡(μ2/m2) and m2n+2logn⁡(μ2/m2)m2n+2logn⁡(μ2/m2), with m the lowest-order pion mass. A side result is the leading divergence for a general heavy baryon loop integral.