Are the irreducible representations of $U(n)$ the same as $SU(n)$?

353 Views Asked by At

I am interested to know whether $U(n)$ has the same (irreducible) representations as $SU(n)$ and why? I have noticed that very often in the literature there is not a clear distinction between these two. The same observation applies for other groups such as $SO(n)$, $O(n)$ and $Sp(2n)$ with $USp(2n)$.