Re: Variation of Generalized Proca Action and equation of motion

[Jose]

Hi,

I attach a notebook with some basic commands using VarD (from xTensor) and VarL (from xTras) to get you started with this type of computation.

There is documentation in xTensorDoc, in xTras, in xAct-contrib and in this forum. See for instance

http://xact.es/Documentation/HTML/HTMLLinks/xTensorDoc.nb_58.html

http://www.xact.es/xtras/documentation/tutorial/MetricVariations.html

http://www.xact.es/xtras/documentation/tutorial/GaussBonnet.html

https://github.com/xAct-contrib/examples

https://groups.google.com/g/xAct/search?q=VarD

https://groups.google.com/g/xAct/search?q=VarL

Cheers,

Jose.

On Monday, September 20, 2021 at 5:27:28 PM UTC-5 тчеорист wrote:

Hello everyone

I'm a very beginner in xAct, and I would like to learn how to vary actions with respect to the metric and A[a] then get the equation of motion (see the picture below)

** those are the Lagrangian of the generalized Prcoa actions used in cosmology

Thank you in advance