# How is the term “Born level” usually defined?

How is the term "Born level" usually defined, e.g. in talking about the $pp\to Z/\gamma^*\to e^+e^-$ cross section at Born level?

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"Born level" is a linguistic mutation of "Born approximation" and "Tree-level". –  Qmechanic Feb 21 '13 at 14:17
Is "Born approximation" in this lingua a synonym for "Tree-level" or something in addition? –  user21223 Feb 21 '13 at 15:47