Scales in nuclear matter: Chiral dynamics with pion nucleon form factors

A systematic calculation of nuclear matter is performed which includes the long-range correlations between nucleons arising from one- and two-pion exchange. Three-body effects from 2π exchange with excitations of virtual Δ(1232)-isobars are also taken into account in our diagrammatic calculation of the energy per particle anti E(kf). In order to eliminate possible high-momentum components from the interactions we introduce at each pion-baryon vertex a form factor of monopole type. The empirical nuclear matter saturation point, ρ0≅0.16 fm-3, anti E0≅-16 MeV, is well reproduced with a monopole mass of Λ≅4πfπ≅1.16 GeV. As in the recent approach based on the universal low-momentum NN potential Vlow-k, the inclusion of three-body effects is crucial in order to achieve saturation of nuclear matter. We demonstrate that the dependence of the pion exchange contributions to anti E(kf) on the ''resolution'' scale Λ can be compensated over a wide range of Λ by counterterms with two ''running'' contact couplings. As a further application we study the in-medium chiral condensate left angle anti qq right angle (ρ) beyond the linear density approximation. For ρ ≤ 1.5ρ0 we find small corrections from the derivative d anti E(kf)/dmπ, which are stable against variations of the monopole regulator mass Λ. (orig.)