In mathematics, it is common to refer to the homomorphism ρ ρ as the representation, for example in the sentence 'consider a representation ρ ρ ', and the vector space V is referred to as the 'representation space'. In physics sometimes the vector space is referred to as the representation, for example in the sentence 'we model the particle as transforming in the singlet representation', or even to refer to a quantum field which takes values in such a representation, and the physical particles which are modelled by such a quantum field.