ScalingStacks

Proof. [044S]

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Proof.

We consider the Laplacian

Δa​(∂wp​q¯∂ηr−∂wr​q∂ηp)=∂∂ηr​Δa​wp​q¯−∂∂ηp​Δa​wr​q=−4​π​A−1​{∂∂ηr​(δ⁡(fS)​zp​z¯q)−∂∂ηp​(δ⁡(fS)​zr​z¯q)}=−4​π​A−1​δ​(fS)​{∂∂ηr​(zp​z¯q)−∂∂ηp​(zr​z¯q)}=0,\begin{split}\Delta_{a}(\frac{\partial w^{p\bar{q}}}{\partial\eta_{r}}-\frac{\partial w^{rq}}{\partial\eta_{p}})=&\frac{\partial}{\partial\eta_{r}}\Delta_{a}w^{p\bar{q}}-\frac{\partial}{\partial\eta_{p}}\Delta_{a}w^{rq}\\ =&-4\pi A^{-1}\{\frac{\partial}{\partial\eta_{r}}(\delta(f_{S})z_{p}\bar{z}_{q})-\frac{\partial}{\partial\eta_{p}}(\delta(f_{S})z_{r}\bar{z}_{q})\}\\ =&-4\pi A^{-1}\delta(f_{S})\{\frac{\partial}{\partial\eta_{r}}(z_{p}\bar{z}_{q})-\frac{\partial}{\partial\eta_{p}}(z_{r}\bar{z}_{q})\}=0,\end{split}

where we have crucially used that SS is an algebraic cycle to deduce ∂δ⁡(fS)=0\partial\delta(f_{S})=0. Thus ∂wp​q¯∂ηr−∂wr​q∂ηp=0\frac{\partial w^{p\bar{q}}}{\partial\eta_{r}}-\frac{\partial w^{rq}}{\partial\eta_{p}}=0 would follow from a Liouville theorem argument, by checking some a priori growth condition

|∂wp​q¯∂ηr|≲{R−1,ϱ≳A1/4,A1/4R−2,ϱ≲A1/4,|\frac{\partial w^{p\bar{q}}}{\partial\eta_{r}}|\lesssim\begin{cases}R^{-1},\quad&\varrho\gtrsim A^{1/4},\\ A^{1/4}R^{-2},\quad&\varrho\lesssim A^{1/4},\end{cases}

which is easy to derive using the techniques in the previous lemmas in this Section. The η¯\bar{\eta} derivatives can be treated similarly. ∎

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