2.3 Simplifications for proportional line bundles [0226]
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2.3 Simplifications for proportional line bundles
A special case of the generalized Calabi ansatz is when is trivial, and for some positive line bundle and positive integers . In this case, we can take , and is the suitable tensor power of , where can be chosen to correspond to the Calabi-Yau metric in the class . The ansatz metric is simply
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Observe that for rank reasons
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We compute the volume form using binomial expansion
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Since already exhaust all base terms, we can replace by , and obtain
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The Calabi-Yau condition on and the normalization on imply
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The conclusion is that
Lemma 2.1.
As long as the NA MA equation holds
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then the generalized Calabi ansatz is a Calabi-Yau metric, in this case of proportional line bundles.
Remark 2.2.
It is understood that is strictly convex, and is positive. These two conditions guarantee the metric is positive definite.