Hello, I was reading and trying to follow up with Pierre Ramond's "Field theory: A modern primer" and got stuck in his step to step jumping. Kindly, see attachment and note that Eq (1.2.6) = g[itex]_{ρσ}[/itex]=g[itex]_{μ\upsilon}[/itex][itex]\Lambda[/itex][itex]^{μ}[/itex][itex]_{ρ}[/itex][itex]\Lambda[/itex][itex]^{\upsilon}[/itex][itex]_{σ}[/itex].(adsbygoogle = window.adsbygoogle || []).push({});

My question is what do I need from tensor calculus to get how did he jump between (1.2.20), (1.2.21), (1.2.22)? Thank you

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# Lorentz transformation, quantum field theory

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