Is Feynman's time-ordering prescription covariant?

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The discussion centers on the covariant nature of the S-matrix theory in relation to time-ordering and Lorentz frames. It is established that time-ordering is frame-dependent, necessitating adjustments during Lorentz boosts to maintain covariance. The S-matrix is confirmed to be unitary and compatible with time-ordering, with a covariant formulation provided by the path integral approach. For further insights, the derivation and explanation of invariance can be found in Landau & Lifshitz's "Quantum Electrodynamics," pages 283-286.

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The discussion is beneficial for theoretical physicists, quantum field theorists, and students seeking to deepen their understanding of covariance in quantum mechanics and the S-matrix framework.

Cinquero
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We all know that time-ordering depends on the choice of Lorentz frame. So my question is somewhat obvious...

Please give me a hint on where to look up that problem, eg. why the S-matrix theory is covariant.

I guess the time-ordering prescription is implicitly defined for each single Lorentz frame (relative times are specific to each frame), and therefore we'll have to adjust the ordering of the operators when applying Lorentz boosts -- thereby rendering the theory covariant in an obvious way. Is that correct?
 
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By definition,the S matrix is both unitary and has no problem with the time ordering.A covariant theory of the S matrix is given in the path integral approach,which,as you might know,is much simpler.

Daniel.
 
The derivation (along with the reason for invariance) is given in Landau & Lif****z's Quantum Electrodynamics, p. 283-286, if the OP wants further reference.
 

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