Name: Aliaksandr Dubrouski (email_not_shown)
Date: 05/05/15-05:45:05 PM Z

2 Lingxiao Xu:

I would suggest to check how factors introduced by Peskin and Shroeder are
related to the C_0 decomposition at certain relation of higgs and quark
mass, the factor 3 came from there. That is not related to the Feyn Calc
per se, it rather the matter of definition of the I(m_H/m_q) from C_0.

2015-05-05 17:54 GMT+03:00 Lingxiao Xu <noreply@feyncalc.org>:

> 2 Aliaksandr:
>
> In the amplitude, the color factor is just Tr[T^a.T^b] which equals to
> \delta^{ab}/2 exactly. So that in the amplitude squared after we sum over
> color indexes a and b, we have \sum_{a,b} (\delta^{ab}/2)
> (\delta^{ab}/2)=2, so I just multiply 2 when the amplitude get squared.
>
>
> Cheers!
>
> Lingxiao Xu
>
> 

-- 
Regards,
            Aliaksandr Dubrouski

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