Name: Lu Jie Date: 11/05/12-03:41:19 PM Z
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