QCD SUM-RULES FOR NUCLEON CURRENT IN A NUCLEUS

QCD sum rules are used to study the nucleon current correlation function in an even-even nucleus in the linear-density approximation. The residue of the double pole of the correlation function at the nucleon mass is related to the nucleon-nucleus scattering amplitudes. The latter in turn are related to phenomenological scalar and vector potentials. We find one of the three sum-rules we study to be most reliable and use it to find an energy-dependent linear combination of the scalar and vector potentials. Interpreted in terms of a pole corresponding to an effective mass for the nucleon in a nucleus, there is a small decrease of the nucleon mass.