Global Analytic Hypoellipticity for a Class of Quasilinear Sums of Squares of Vector Fields

A global real analytic regularity theorem for a quasilinear sum of squares of vector fields of Hormander rank 2 is given. A related local result for a special case was proved recently by the second author and L. Zanghirati in a paper titled “Local Real Analyticity of Solutions for sums of squares of non-linear vector fields”.