Quadratic differential
= Quadratic differential
{title2=$q=\phi(z)\,dz^2$}
{wiki}
A section of the square of the <canonical bundle>, locally $q=\phi(z)\,dz^2$; its coefficient changes by the square of the coordinate <derivative>. A <holomorphic quadratic differential> has <holomorphic> coefficient, and its <flat metric of a quadratic differential> is $|q|^{1/2}$.