QCD SUM-RULES FOR NUCLEONS IN NUCLEAR-MATTER

The self-energies of quasinucleon states in nuclear matter are studied using QCD sum-rule methods. A correlator of nucleon interpolating fields, evaluated in the finite-density ground state, is calculated using both an operator product expansion and a dispersion relation with a spectral ansatz. This approach relates the nucleon spectral properties (such as the quasinucleon self-energies) to matrix elements of QCD composite operators (condensates). With increasing nucleon density, large changes in Lorentz scalar and vector self-energies arise naturally; the self-energies are found to be comparable to those suggested by relativistic nuclear physics phenomenology. The most important phenomenological inputs are the baryon density and the value of the nucleon sigma term divided by the average current mass of the light quarks. However, the successful comparison to relativistic phenomenology is sensitive to assumptions made about the density dependence of certain four-quark condensates.