Equilibrium of nuclear matter in QCD sum rules

摘要

.We calculate the nucleon parameters in symmetric nuclear matter employing the QCD sum rules approach. We focus on the average energy per nucleon and study the equilibrium states of the matter. We treat the matter as a relativistic system of interacting nucleons. Assuming the dependence of the nucleon mass on the light quark mass mq to be more important than that of nucleon interactions we find that the contribution of the relativistic nucleons to the scalar quark condensate can be expressed as that caused by the nucleon matrix element multiplied by the density dependent factor F() caused by the relativistic motion of nucleons composing the matter. We demonstrate that there are no equilibrium states while we include only the condensates with dimension d3. There are equilibrium states if we include the lowest order radiative corrections and the condensates with d4. They manifest themselves for the nucleon sigma term sigma N>60 MeV. Including the condensates with d6 we find equilibrium states of nuclear matter for sigma N>41 MeV. In all cases the equilibrium states are due to influence of the relativistic motion of nucleons on the scalar quark condensate.