Many body effects in nuclear matter QCD sum rules

摘要

AbstractWe calculate the single-particle nucleon characteristics in symmetric nuclear matter with inclusion of the 3Nand 4Ninteractions. We calculated the contribution of the 3Ninteractions earlier, now we add that of the 4Nones. The contribution of the 4Nforces to nucleon self energies is expressed in terms of the nonlocal scalar condensate (d=3) and of the configurations of the vector–scalar and the scalar–scalar quark condensates (d=6) in which two diquark operators act on two different nucleons of the matter.These four-quark condensates are obtained in the model-independent way. The density dependence of the nucleon effective mass, of the vector self energy and of the single-particle potential energy are obtained. We traced the dependence of the nucleon characteristics on the actual value of the pion–nucleon sigma term. We obtained also the nucleon characteristics in terms of the quasifree nucleons, with the noninteracting nucleons surrounded by their pion clouds as the starting point. This approach leads to strict hierarchy of the many body forces.]]>