Proof.
Consider at a given point in the region (4.14).
Its integral formula (4.11) can be split into two parts, corresponding to far away sources and nearby sources .
For far away sources, we use Lemma 4.1 to write the integrand as a dominant term plus a remainder term estimated by . The dominant term does not contribute to because it is constant in the direction. The remainder term contribution to is bounded by
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The contribution from nearby sources only arises if our given point of interest is too close to along one of , or directions; we focus on . Lemma 4.2 allows us to write as plus a well controlled remainder term. By the exponential decay property of the measure ,
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Combining the above shows .
All these arguments carry through to except the exponential decay of the measure. This is compensated by staying sufficiently far from . ∎