Abstract
We calculate the density-dependent spin-asymmetry energy S(kf) of isospin-symmetric nuclear matter in the three-loop approximation of chiral perturbation theory. The interaction contributions to S(kf) originate from one-pion exchange, iterated one-pion exchange, and (irreducible) two-pion exchange with no, single, and double virtual Δ-isobar excitation. We find that the truncation to 1 π-exchange and iterated 1 π-exchange terms (which leads already to a good nuclear matter equation of state) is spin unstable, since S(kf0) < 0. The inclusion of the chiral πNΔ dynamics guarantees the spin stability of nuclear matter. The corresponding spin-asymmetry energy S(kf) stays positive within a wide range of an undetermined short-range parameter S5 (which we also estimate from realistic NN potentials). Our results reemphasize the important role played by two-pion exchange with virtual Δ-isobar excitation for the nuclear matter many-body problem. Its explicit inclusion is essential in order to obtain good bulk and single-particle properties.
Original language | English |
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Article number | 054001 |
Pages (from-to) | 054001-1-054001-7 |
Journal | Physical Review C - Nuclear Physics |
Volume | 70 |
Issue number | 5 |
DOIs | |
State | Published - Nov 2004 |