The relativistic generalization of the screened potential problem is given. The Klein–Gordon and Dirac equations in the presence of the Hulthén potential V(r)=−αδe−δr/(1−e−δr) are solved by using the usual approximation of the centrifugal potential. The approach proposed by Biedenharn for the Dirac–Coulomb problem is applied to the spin- case. The energy spectrum and the scattering function are obtained both for spin-0 and spin- particles. The nonrelativistic limit is discussed. When the screening parameter δ vanishes, it is shown that the obtained wavefunctions and energies become the same as that of the Coulomb potential.

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The supersymetric path integrals in solving the problem of relativistic spinning particle interacting with pseudoscalar potentials is examined. The relative propagator is presented by means of path integral, where the spin degrees of freedom are described by odd Grassmannian variables and the gauge invariant part of the effective action has a form similar to the standard pseudoclassical action given by Berezin and Marinov. After integrating over fermionic variables (Grassmannian variables), the problem is reduced to a nonrelativistic one with an effective supersymetric potential. Some explicit examples are considered, where we have extracted the energy spectrum of the electron and the wave functions.