ScalingStacks

Lemma 2.1 . [03ZI]

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Lemma 2.1.

The functions

(2.6) {α1​(μ1,μ2,η)=12​μ12+a22​|η|2​{12+1π​arctan⁡(a22​μ2+a12​μ1A​μ12+a22​|η|2)},α2​(μ1,μ2,η)=12​μ22+a11​|η|2​{12+1π​arctan⁡(a11​μ1+a12​μ2A​μ22+a11​|η|2)},α3​(μ1,μ2,η)=12​(μ1−μ2)2+(a11+2​a12+a22)​|η|2{12+1π​arctan⁡(−a11​μ1−a12​μ2−a21​μ1−a22​μ2A​(μ1−μ2)2+(a11+a12+a21+a22)​|η|2)}\begin{cases}\alpha_{1}(\mu_{1},\mu_{2},\eta)=&\frac{1}{2\sqrt{\mu_{1}^{2}+a_{22}|\eta|^{2}}}\{\frac{1}{2}+\frac{1}{\pi}\arctan(\frac{a_{22}\mu_{2}+a_{12}\mu_{1}}{\sqrt{A}\sqrt{\mu_{1}^{2}+a_{22}|\eta|^{2}}})\},\\ \alpha_{2}(\mu_{1},\mu_{2},\eta)=&\frac{1}{2\sqrt{\mu_{2}^{2}+a_{11}|\eta|^{2}}}\{\frac{1}{2}+\frac{1}{\pi}\arctan(\frac{a_{11}\mu_{1}+a_{12}\mu_{2}}{\sqrt{A}\sqrt{\mu_{2}^{2}+a_{11}|\eta|^{2}}})\},\\ \alpha_{3}(\mu_{1},\mu_{2},\eta)=&\frac{1}{2\sqrt{(\mu_{1}-\mu_{2})^{2}+(a_{11}+2a_{12}+a_{22})|\eta|^{2}}}\\ &\{\frac{1}{2}+\frac{1}{\pi}\arctan(\frac{-a_{11}\mu_{1}-a_{12}\mu_{2}-a_{21}\mu_{1}-a_{22}\mu_{2}}{\sqrt{A}\sqrt{(\mu_{1}-\mu_{2})^{2}+(a_{11}+a_{12}+a_{21}+a_{22})|\eta|^{2}}})\}\end{cases}

satisfy the equations on measures

(2.7) {(Δaα1)dVola=−2πA∫𝔇1dμ2,(Δaα2)dVola=−2πA∫𝔇2dμ1,(Δa​α3)​d​Vola=2​π​A​∫𝔇3d​μ1\begin{cases}(\Delta_{a}\alpha_{1})d\text{Vol}_{a}=-2\pi\sqrt{A}\int_{\mathfrak{D}_{1}}d\mu_{2},\\ (\Delta_{a}\alpha_{2})d\text{Vol}_{a}=-2\pi\sqrt{A}\int_{\mathfrak{D}_{2}}d\mu_{1},\\ (\Delta_{a}\alpha_{3})d\text{Vol}_{a}=2\pi\sqrt{A}\int_{\mathfrak{D}_{3}}d\mu_{1}\end{cases}

where the RHS are signed measures supported on 𝔇1,𝔇2,𝔇3\mathfrak{D}_{1},\mathfrak{D}_{2},\mathfrak{D}_{3}. Morever,

(2.8) ∂α1∂μ2=∂α2∂μ1=(−∂∂μ1−∂∂μ2)​α3=A2​π​|μ→|a2.\frac{\partial\alpha_{1}}{\partial\mu_{2}}=\frac{\partial\alpha_{2}}{\partial\mu_{1}}=(-\frac{\partial}{\partial\mu_{1}}-\frac{\partial}{\partial\mu_{2}})\alpha_{3}=\frac{\sqrt{A}}{2\pi|\vec{\mu}|_{a}^{2}}.

The singularity of αi\alpha_{i} occurs along 𝔇i\mathfrak{D}_{i} and modulo smooth terms looks like

{α1∼12​μ12+a22​|η|2,α2∼12​μ22+a11​|η|2,α3∼12​(μ1−μ2)2+(a11+2​a12+a22)​|η|2.\begin{cases}\alpha_{1}\sim\frac{1}{2\sqrt{\mu_{1}^{2}+a_{22}|\eta|^{2}}},\\ \alpha_{2}\sim\frac{1}{2\sqrt{\mu_{2}^{2}+a_{11}|\eta|^{2}}},\\ \alpha_{3}\sim\frac{1}{2\sqrt{(\mu_{1}-\mu_{2})^{2}+(a_{11}+2a_{12}+a_{22})|\eta|^{2}}}.\end{cases}

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