# Levi-Civita definition

Asked by IvanSobolev

Dear MG5 developers,

What is the definition for Levi-Civita tensor? Is it epsilon^{0123} = +1, or epsilon^{0123} = -1 (I mean upper indices here). Sorry if it is a stupid question but I couldn't find an answer in a manual (https://arxiv.org/pdf/1108.2040.pdf).

Thank you!

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Olivier Mattelaer
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 Revision history for this message Olivier Mattelaer (olivier-mattelaer) said on 2017-03-04: #1

Hi,

The convention is
Epsilon(0,1,2,3) = -1

Cheers,

Olivier

> On 4 Mar 2017, at 14:14, IvanSobolev <email address hidden> wrote:
>
> New question #525474 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/525474
>
> Dear MG5 developers,
>
> What is the definition for Levi-Civita tensor? Is it epsilon^{0123} = +1, or epsilon^{0123} = -1 (I mean upper indices here). Sorry if it is a stupid question but I couldn't find an answer in a manual (https://arxiv.org/pdf/1108.2040.pdf).
>
> Thank you!
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

 Revision history for this message IvanSobolev (sobolev-ivan) said on 2017-03-04: #2

Thank you!

 Revision history for this message IvanSobolev (sobolev-ivan) said on 2017-03-04: #3

Thanks Olivier Mattelaer, that solved my question.

 Revision history for this message marco zaro (marco-zaro) said on 2020-08-31: #4

Hi Olivier,
about this question, I think it matters if the lorentz indices are low or up, doesn't it (there is a minus sign entering..)?
In case, what is used?
Cheers,

Marco

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