Weak Containment and Tensor Products of Group Representations.
When is there a discontinuous homomorphism from L¹(G)?
Let A be an A*-algebra with enveloping C*-algebra C*(A). We show that, under certain conditions, a homomorphism from C*(A) into a Banach algebra is continuous if and only if its restriction to A is continuous. We apply this result to the question in the title.