“…Mathematical modelling of the collective behavior of individuals, such as swarming, has also been treated by continuum models steaming from discrete particle models [30,14,38,31,39,15,33,13,21,22,16,17]. Typical examples of interaction potentials appearing in these works are the attractive Morse potential W (x) = −e −|x| , attractiverepulsive Morse potentials W (x) = −C a e −|x|/ a + C r e −|x|/ r , W (x) = −e −|x| 2 , W (x) = −C a e −|x| 2 / a + C r e −|x| 2 / r , or W being the characteristic function of a set in R d .…”