A note on quantum Hamiltonian reduction and anomalies

Quantization of field-theoretic models with gauge symmetries is often obstructed by quantum anomalies. It is commonly believed that the origin of these anomalies lies in the infinite number of degrees of freedom, which requires completing the model within an appropriate regularization scheme. This paper provides an explicit example of a finite-dimensional Hamiltonian system with first-class constraints whose quantization exhibits anomalies. These anomalies arise from the nontrivial topology of the reduced phase space.