Macroscopic Effects of Quantum Anomalies
APA
Mottola, E. (2018). Macroscopic Effects of Quantum Anomalies . Perimeter Institute. https://pirsa.org/18100087
MLA
Mottola, Emil. Macroscopic Effects of Quantum Anomalies . Perimeter Institute, Oct. 17, 2018, https://pirsa.org/18100087
BibTex
@misc{ pirsa_PIRSA:18100087, doi = {10.48660/18100087}, 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.