Spin symmetry energy and spin dependence of the single particle potential in nuclear matter

In the presence of tensor nuclear forces, the single particle energy in spin and spin–isospin polarized nuclear matter is diagonal in nucleon spin states with the spin quantization axis tilting away from the direction in which nuclear matter is polarized. This tilting of nucleon spins is taken into account in determining the shape of Fermi surfaces in spin and spin–isospin polarized nuclear matter, and in relating the spin and spin–isospin dependent components of the single particle potential, and the spin and spin–isospin symmetry energies of nuclear matter to the Landau parameters of the quasi-particle interaction. Numerical results are obtained partly with empirical values of the Landau parameters, and partly with values calculated with the Sprung effective two-body interaction in nuclear matter.