Name: Vladyslav Shtabovenko Date: 12/19/16-02:56:23 PM Z
Hi,
in fact, since FeynCalc 9.2 GS[0] does evaluate to 0, i.e.
GS[p] /. p -> 0
gives 0, while GA[0]
evaluates to
DiracGamma[ExplicitLorentzIndex[0]]
Cheers,
Vladyslav
>
>
> Hello,
>
> I\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\‘m
working with loop integral involve terms like GS[p], and the
moment
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\“p\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\”
need to be put as zero. But I found something strange:
>
_____________________________________
> In[19]:= GS[p] /. p -> 0
>
> Out[19]=
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[Gamma]\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[CenterDot]0
> ————————————————
>
> or you can see it more clearly using the StandardForm
> ————————————————
> In[20]:= GS[p] /. p -> 0 // StandardForm
>
> Out[20]//StandardForm= GS[0]
> ————————————————
>
> The result should be zero though. It looks like FeynCalc or
Mathematica treat the GS[] as a function but without definition
of GS[0] =0.
>
> Furthermore, when the OneLoop involves the GS[0], it will
become GA[0]
>
________________________________________
> In[22]:= OneLoop[p, GS[p] /. p -> 0]
>
> Out[22]=
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[Gamma]^0
>
________________________________________
>
> Similar thing happens on the SPD[k,p], it will be zero when
you replace one of the moment to be zero, but
>
> In[30]:= Spinor[k, MT] SPD[k, p] /. p -> 0
//
>
> Out[30]= 0
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\CurlyPhi
>
> or in StandardForm
> Out[31]= SPD[0, k] Spinor[Momentum[k],
MT, 1]
>
> And this
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\“0\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\”
or SPD[0,k] will become GA[0].GA[0] after
applied the OneLoop function in my loop integral.
>
> Could you please look into this case?
> Thank you very much!
>
> Lu Jie