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Helicity-dependent distribution of strange quarks in the proton from nonlocal chiral effective theory

The helicity-dependent strange quark distribution in the proton, $Δs$, is calculated in a nonlocal chiral SU(3) effective field theory. The hadronic proton to meson plus octet or decuplet baryon splitting functions are derived at the one-loop level, with loop integrals rendered finite by correlation functions introduced in the nonlocal Lagrangian. Within the convolution framework, the proton strange helicity distribution is obtained using spin-flavor symmetry to constrain the input valence quark distributions in the hadronic intermediate states. The polarized strange quark distribution is found to be quite small, with the lowest moment of $Δs$ negative, but consistent with recent global QCD analyses.