The giant collective modes in asymmetric nuclear matter are investigated
within a dynamic relaxation time approximation. We derive a coupled dispersion
relation and show that two sources of coupling appear: (i) a coupling of
isoscalar and isovector modes due to different mean-fields acting and (ii) an
explicit new coupling in asymmetric matter due to collisional interaction. We
show that the latter one is responsible for a new mode arising besides
isovector and isoscalar modes.Comment: Varenna conference proceeding
