Paper detail

The bifurcation diagram of cubic polynomial vector fields on $\mathbb{C}\mathbb{P}^1$

In this paper we give the bifurcation diagram of the family of cubic vector fields $\dot z=z^3+ ε_1z+ε_0$ for $z\in \mathbb{C}\mathbb{P}^1$, depending on the values of $ε_1,ε_0\in\mathbb{C}$. The bifurcation diagram is in $\mathbb{R}^4$, but its conic structure allows describing it for parameter values in $\mathbb{S}^3$. There are two open simply connected regions of structurally stable vector fields separated by surfaces corresponding to bifurcations of homoclinic connections between two separatrices of the pole at infinity. These branch from the codimension 2 curve of double singular points. We also explain the bifurcation of homoclinic connection in terms of the description of Douady and Sentenac of polynomial vector fields.