Non-Linear Effects in a Yamabe-Type Problem with Quasi-Linear Weight

We study the quasi-linear minimization problem on $H^1_0(\Omega)\subset L^q$ with $q=\frac{2n}{n-2}$~: $$\inf_{\|u\|_{L^q}=1}\int_\Omega (1+|x|^\beta |u|^k)|\nabla u|^2.$$ We show that minimizers exist only in the range $\beta<kn/q$ which corresponds to a dominant non-linear term. On the contrary, the linear influence for $\beta\geq kn/q$ prevents their existence.