Name: Rolf Mertig Date: 02/21/01-02:15:23 PM Z
Hi,
this seems to be a bug (and it wasn’t there some years ago; I cannot
see quickly what causes it).
However, it is easy to work around:
Mathematica 4.1 for Linux
Copyright 1988-2000 Wolfram Research, Inc.
– Motif graphics initialized –
In[1]:= !!t.m
<<HighEnergyPhysics`fc`
(* set FI for InputForm and FCE for short external form *)
FI;
amp=SpinorUBar[k].GA[\[Mu]].(1 -
\[Lambda] GA[5]).SpinorU[p, m];
Print[“amp = “, FCE@amp];
(* using Calc basically expand here the (1-\[Lambda]
GA[5]);
ComplexConjugate works right then
*)
ccamp = ComplexConjugate[ Calc[amp] ];
Print[”\n ccamp = “, FCE@ccamp];
(* use FermionSpinSum to do the trace step by step *)
spinsu = FermionSpinSum[ FCI[ Expand[amp ccamp] ]
]
Print[”\n spinsu = “, FCE@spinsu];
(* doing the trace *)
r1 = spinsu /. DiracTrace -> Tr;
Print[”\n r1 = “, FCE@r1];
(* However, one can also do it immediately: *)
r2 = SquareAmplitude[ amp ]
Print[”\n r2 = “, FCE@r2];
(* check it *)
Calc[ r1 - r2]
In[1]:= <<t.m
FeynCalc4.1.0.3b Type ?FeynCalc for help or visit
http://www.feyncalc.org
$PrePrint is set to FeynCalcForm. Use FI and FC to change the display
format.
amp = SpinorUBar[k] . GA[\[Mu]] . (1 -
\[Lambda] GA[5]) . SpinorU[p, m]
Spinor[Momentum[p], m, 1] .
GA[ComplexIndex[\[Mu]]] .
ccamp =
Spinor[Momentum[k], 0, 1] + \[Lambda]
Spinor[Momentum[p], m, 1] . GA[5] .
GA[ComplexIndex[\[Mu]]] .
Spinor[Momentum[k], 0, 1]
DiracTrace[(m + GS[p]) .
GA[ComplexIndex[\[Mu]]] . GS[k] .
spinsu =
GA[\[Mu]] . (1 - \[Lambda]
GA[5])] +
\[Lambda] DiracTrace[GS[k] .
GA[\[Mu]] . (1 - \[Lambda] GA[5]) .
(m + GS[p]) . GA[5] .
GA[ComplexIndex[\[Mu]]]]
4 \[Lambda] (\[Lambda] FV[k,
ComplexIndex[\[Mu]]] FV[p, \[Mu]]
Rolf
Timur Rashba wrote:
>
> Hello Rolf!
>
> Sorry for troubling you.
>
> Could you help me in my work with FeynCalc.
> It’s very nice package but I couldn’t understand some results.
>
> Why
>
*>
ComplexConjugate[SpinorUBar[k].GA[\[Mu]].(1