LToolsExpandInEpsilon
is an option for
LToolsEvaluate
. When set to True
(default),
the result returned by LoopTools and multiplied with proper conversion
factors will be expanded around to .
The -dependent conversion
factors arise from the differences in the normalization between
Passarino-Veltman functions in FeynCalc and LoopTools. In addition to
that, the prefactor specified via LToolsImplicitPrefactor
may also depend on .
Setting this option to False
will leave the prefactors
unexpanded, which might sometimes be useful when examining the obtained
results.
Overview, LToolsEvaluate, LToolsImplicitPrefactor.
[] LToolsLoadLibrary
(* ====================================================
FF 2.0, a package to evaluate one-loop integrals
written by G. J. van Oldenborgh, NIKHEF-H, Amsterdam
====================================================
for the algorithms used see preprint NIKHEF-H 89/17,
'New Algorithms for One-loop Integrals', by G.J. van
Oldenborgh and J.A.M. Vermaseren, published in
Zeitschrift fuer Physik C46(1990)425.
====================================================*)
The default behavior of LToolsEvaluate
is to do the
-expansion automatically
[FAD[q, q - p], q, InitialSubstitutions -> {SPD[p] -> 1}] LToolsEvaluate
This can be disabled by setting LToolsExpandInEpsilon
to
False
[FAD[q, q - p], q, InitialSubstitutions -> {SPD[p] -> 1}, LToolsExpandInEpsilon -> False] LToolsEvaluate