Dispersion Formulas in QFTs, CFTs, and Holography

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We study momentum space dispersion formulas in general QFTs and their applications for CFT correlation functions.

• We show, using two independent methods, that QFT dispersion formulas can be written in terms of causal commutators.
• The first derivation uses analyticity properties of retarded correlators in momentum space.
• The second derivation uses the largest time equation and the defining properties of the time-ordered product.