Anomalies at finite density and chiral fermions

Understand

Using perturbation theory in the Euclidean (imaginary time) formalism as well as the non-perturbative Fujikawa method, we verify that the chiral anomaly equation remains unaffected in the presence of nonzero chemical potential, $\mu$.

• We extend our considerations to fermions with exact chiral symmetry on the lattice and discuss the consequences for the recent Bloch-Wettig proposal for the Dirac operator at finite chemical potential.
• We propose a new simpler method of incorporating $\mu$ and compare it with the Bloch-Wettig idea.