ScalingStacks

Proof. [051R]

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Proof.

To see Θ1\Theta_{1} is a well-defined, we consider the change of unitary frame 𝒆\bm{e} on N0N_{0} to 𝒆~=eβˆ’1​k​ϕ​𝒆\tilde{\bm{e}}=e^{\sqrt{-1}k\phi}\bm{e}, then we have

(4.55) y~=eβˆ’(kβˆ’βˆ’k+)β€‹βˆ’1​ϕ​y;u~1=ek+β€‹βˆ’1​ϕ​u1,u~2=eβˆ’kβˆ’β€‹βˆ’1​ϕ​u2.\tilde{y}=e^{-(k_{-}-k_{+})\sqrt{-1}\phi}y;\ \ \tilde{u}_{1}=e^{k_{+}\sqrt{-1}\phi}u_{1},\tilde{u}_{2}=e^{-k_{-}\sqrt{-1}\phi}u_{2}.

for some local real-valued function Ο•\phi on HH. Then we get

(4.56) uΒ―1​d​u1βˆ’u1​d​uΒ―1\displaystyle\bar{u}_{1}du_{1}-u_{1}d\bar{u}_{1} =u~Β―1​d​u~1βˆ’u~1​d​u~Β―1βˆ’2​k+β€‹βˆ’1​|u1|2​d​ϕ,\displaystyle=\bar{\tilde{u}}_{1}d\tilde{u}_{1}-\tilde{u}_{1}d\bar{\tilde{u}}_{1}-2k_{+}\sqrt{-1}|u_{1}|^{2}d\phi,
(4.57) uΒ―2​d​u2βˆ’u2​d​uΒ―2\displaystyle\bar{u}_{2}du_{2}-u_{2}d\bar{u}_{2} =u~Β―2​d​u~2βˆ’u~2​d​u~Β―2+2​kβˆ’β€‹βˆ’1​|u2|2​d​ϕ,\displaystyle=\bar{\tilde{u}}_{2}d\tilde{u}_{2}-\tilde{u}_{2}d\bar{\tilde{u}}_{2}+2k_{-}\sqrt{-1}|u_{2}|^{2}d\phi,
(4.58) Ξ“\displaystyle\Gamma =Ξ“~βˆ’kβˆ’βˆ’k+2​d​ϕ.\displaystyle=\widetilde{\Gamma}-\frac{k_{-}-k_{+}}{2}d\phi.

Then it is a straightforward to compute that Θ~1=Θ1\widetilde{\Theta}_{1}=\Theta_{1}, which shows that Θ1\Theta_{1} is globally defined.

Now we consider the local expansion of Ξ₯\Upsilon. First differentiating the expansion of ψ\psi in Proposition 3.24 we get

(4.59) βˆ‚zΟ‰~=βˆ’βˆ’1​z2​r3​d​y∧d​yΒ―βˆ’z2​r3​(y​d​yΒ―+y¯​d​y)βˆ§Ξ“+zr​d​Γ+O′​(1)​d​y+O′​(1)​d​yΒ―+O′​(r).\partial_{z}\tilde{\omega}=-\sqrt{-1}\frac{z}{2r^{3}}dy\wedge d\bar{y}-\frac{z}{2r^{3}}(yd\bar{y}+\bar{y}dy)\wedge\Gamma+\frac{z}{r}d\Gamma+O^{\prime}(1)dy+O^{\prime}(1)d\bar{y}+O^{\prime}(r).

Next, applying Proposition 3.28 and Proposition 3.26, we obtain

(4.60) dDc​h=dDc​(12​r+O′​(r))=βˆ’14​r3​dDc​|y|2+O′​(1)=βˆ’βˆ’1​(y​d​yΒ―βˆ’y¯​d​y)+4​|y|2​Γ4​r3+O′​(1).d_{D}^{c}h=d_{D}^{c}(\frac{1}{2r}+O^{\prime}(r))=-\frac{1}{4r^{3}}d_{D}^{c}|y|^{2}+O^{\prime}(1)=-\frac{\sqrt{-1}(yd\bar{y}-\bar{y}dy)+4|y|^{2}\Gamma}{4r^{3}}+O^{\prime}(1).

Putting together these, and noting that dβ€‹Ξ˜0d\Theta_{0} is given as in (2.50), we obtain

(4.61) dβ€‹Ξ˜1βˆ’Ξ₯=O′​(1)​d​y+O′​(1)​d​yΒ―+O′​(r)+O′​(1)​d​z.d\Theta_{1}-\Upsilon=O^{\prime}(1)dy+O^{\prime}(1)d\bar{y}+O^{\prime}(r)+O^{\prime}(1)dz.

Now translating into the coordinates u1,u2u_{1},u_{2} on 𝕃\mathbb{L} we obtain the conclusion.

∎

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