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. KaiserPhysik 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
. 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
-exchange). We also consider
the equation of state of pure neutron matter
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.
12.38.Bx - Perturbative calculations.
21.65.+f - Nuclear matter.
© Società Italiana di Fisica, Springer-Verlag 2003
