West is an option for DiracTrace and
several other functions that deal with traces of Dirac matrices. The
option applies only to the computation of D-dimensional traces with an odd number of
\gamma ^5 in the
Breitenlohner-Maison-t’Hooft-Veltman (BMHV) scheme. With
West -> True (default setting), such traces are computed
according to formula (A.5) from Comp. Phys. Comm 77 (1993) 286-298,
which is also known as West’s formula. For more details, see the
documentation of DiracTrace.