S-wave resonances of positron-helium and positron-lithium systems in kappa-distribution plasmas are investigated using Hylleraas-type wave functions in the framework of the stabilization method. A model potential approach is used to represent the interactions between the outer electron, the positron and the core. The resonance parameters (position and width) of positron-helium and positron-lithium systems below the Ps(2s) threshold are reported as a function of screening parameter and spectral index of plasma.

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