As a result of the symmetry properties of the nuclear force the form of the particle-hole interaction can be written as the sum of terms with different spin and isospin dependence. For the specific case of isospin symmetric nuclear matter the p-h force has the form [Ost92]
In the so-called Landau limit, which describes small excitations near the
Fermi surface, the particle and hole momenta, 
and 
, are both near the Fermi momentum and thus roughly
equal to each other in magnitude. Therefore, the interaction terms will only
depend on the angle between 
and 
and can
be expanded in terms of Legendre polynomials, 
. For very short range interactions only the first few terms in
the expansion will be significant, and for contact interactions only the
l=0 term is important. Therefore, for zero-range interactions the
Landau-Migdal
theory for effective p-h interactions is usually written as
where the radial dependence of the 
term is given by the nuclear
charge distribution and 
is the inverse of the density of state,
302 MeV
where 
is the Fermi momentum and 
is the quasiparticle
effective mass.