2019 Impact factor 2.176
Hadrons and Nuclei
Eur. Phys. J. A 17, 11-18 (2003)
DOI: 10.1140/epja/i2002-10149-x

Single-particle potential in a chiral approach to nuclear matter including short-range NN-terms

S. Fritsch and N. Kaiser

Physik Department T39, Technische Universität München, D-85747 Garching, Germany

nkaiser@physik.tu-muenchen.de

(Received: 19 December 2002 / Published online: 15 April 2003)

Abstract
We extend a recent chiral approach to nuclear matter of Lutz et al.  (Phys. Lett. B 474, 7 (2000)) by calculating the underlying (complex-valued) single-particle potential $U(p,k_f)+i\,W(p,k_f)$. The potential for a nucleon at the bottom of the Fermi sea, U(0,kf0)= - 20.0 MeV, comes out as much too weakly attractive in this approach. Even more seriously, the total single-particle energy does not rise monotonically with the nucleon momentum p, implying a negative effective nucleon mass at the Fermi surface. Also, the imaginary single-particle potential, W(0,kf0)= 51.1 MeV, is too large. More realistic single-particle properties together with a good nuclear-matter equation of state can be obtained if the short-range contributions of non-pionic origin are treated in mean-field approximation (i.e. if they are not further iterated with $1\pi$-exchange). We also consider the equation of state of pure neutron matter $\bar E_n(k_n)$ and the asymmetry energy A(kf) in that approach. The downward bending of these quantities above nuclear-matter saturation density seems to be a generic feature of perturbative chiral pion-nucleon dynamics.

PACS
12.38.Bx - Perturbative calculations.
21.65.+f - Nuclear matter.

© Società Italiana di Fisica, Springer-Verlag 2003