The algebra class for the classical Lie algebras are A, B, C, D, while for exceptional algebras it coincides with the algebra itself, i.e. E6, E7, E8, F4 and G2. The
27
of
E
6
can be entered via its Dynkin label (000010):
In[2]:=
Irrep[E6][0,0,0,0,1,0]//TraditionalForm
Out[2]//TraditionalForm=
27
Alternatively irreps can be entered by their dimensional name. Instead of the algebra class one must specify the algebra itself. The input is converted to the unique form with algebra class and Dynkin label:
In[1]:=
Irrep[SU5][10]//FullForm
Out[1]//FullForm=
Irrep[A][0,1,0,0]
Conjugated irreps can be entered by applying the head Bar to the dimension:
In[2]:=
Irrep[SU5][Bar[10]]//FullForm
Out[2]//FullForm=
Irrep[A][0,0,1,0]
and irreps with a prime by the head IrrepPrime, which can be combined with Bar in any order: