Macroscopic Effects of Quantum Anomalies


Mottola, E. (2018). Macroscopic Effects of Quantum Anomalies . Perimeter Institute. https://pirsa.org/18100087


Mottola, Emil. Macroscopic Effects of Quantum Anomalies . Perimeter Institute, Oct. 17, 2018, https://pirsa.org/18100087


          @misc{ pirsa_18100087,
            doi = {},
            url = {https://pirsa.org/18100087},
            author = {Mottola, Emil},
            keywords = {Other},
            language = {en},
            title = {Macroscopic Effects of Quantum Anomalies },
            publisher = {Perimeter Institute},
            year = {2018},
            month = {oct},
            note = {PIRSA:18100087 see, \url{https://pirsa.org}}


In this first of two lectures, intended to be a pedagogical introduction, I will review the quantum field theory origin of anomalies starting with the more familiar example of the axial anomaly in QED, emphasizing the infrared effects and the appearance of a two-particle massless state, similar to a Cooper pairing in superconductor, associated with both the axial and conformal anomalies in two and four dimensions. In both cases the effective action of the anomaly is non-local, but may be expressed in a local form by the introduction of a bosonic field, which one can verify becomes a bona fide propagating quantum field in its own right. At finite chiral chemical potential this boson is a chiral density wave, a gapless pseudo-scalar collective excitation of the Fermi surface of a dissipationless chiral superfluid, analogous to the Goldstone-Nambu boson of spontaneous symmetry breaking. In the limit of vanishing chiral background the boson is a chiral collective mode of the Dirac vacuum itself, which therefore supports an axion-like boson excitation with a two-photon coupling, arising directly from the axial anomaly.