Name: Dimitry (email_not_shown)
Date: 02/14/06-06:00:41 PM Z

Hi all!

Are Lorenz indexes properly contracted in lagrangian expressions like as in Lagrangian["QCD"]?
I meet absolutely unexpected result of "FeynRule" operation with, for example, lagrangian like Lagrangian["QCD"]*QuantumField[S] for generation of 2gluon-scalar vertex.

Same problem persists if instead Lagrangian["QCD"] I’d construct needed composition from vector field using "FieldStrength" utility (or writing strength tensor explicitly).

Problem do not appear if (1) field arguments in "FieldStrength" are with different fields (and expecting only 1/2 of required vertex) and if (2) two strength tensors have different Lorenz indexes, but additional "MT" tensors are included in lagrangian expression for proper further contractions.

It seems that Lorenz contraction is default operation in lagrangian constructions or in "FeynRule" operation.

File with calculations I’m ready to send if needed.

Regards, Dimitry.

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