Taming the Pion Cloud of the Nucleon

We present a light-front determination of the pionic contribution to the nucleon self-energy, $Σ_π$, to second-order in pion-baryon coupling constants that allows the pion-nucleon vertex function to be treated in a model-independent manner constrained by experiment. The pion mass $μ$ dependence of $Σ_π$ is consistent with chiral perturbation theory results for small values of $μ$ and is also linearly dependent on $μ$ for larger values, in accord with the results of lattice QCD calculations. The derivative of $Σ_π$ with respect to $μ^2$ yields the dominant contribution to the pion content, which is consistent with the $\bar{d}-\bar{u}$ difference observed experimentally in the violation of the Gottfried sum rule.

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