Name: Peter Meinzinger Date: 02/02/17-02:45:50 PM Z
Hello,
i’ve got a question regarding the “Head StandardMatrixElement”.
I’m doing a one loop calculation and want to select the coefficients of
the matrix elements in a list.
I solve the problem using the function TID and got information that
formerly, using the function OneLoop, it was possible to access the
coefficients by something like
var=Select[Variables[ans1],(Head[#]===StandardMatrixElement)\&]
now this gives no output, though.
Could you explain what has changed in TID’s output in regard to
OneLoop’s?
Kind regards,
Peter
PS: I’m using version 9.2 (development version) and a example code would be
$BreitMaison = True
num1 := SpinorUBar[p3, ms].GA[6].(GS[q] +
mt).GA[7].PolarizationVector[p2,
\[Mu]].(2*FV[q, \[Mu]] + 2*FV[p1,
\[Mu]] + FV[p2, \[Mu]]).SpinorU[p1,
mb] // DiracSimplify
amp1 = num1*FAD[{q, mt}, {q + p1, mh}, {q + p1 + p2, mh}]
res1 = -I/Pi\.b2*TID[amp1 , q]
var = Select[Variables[res1], (Head[#] === StandardMatrixElement) \&]