IAS High Energy Theory Seminar

Abstract: A key property of a global symmetry's anomaly is its order: the smallest integer n for which the diagonal symmetry of the n-copy system is anomaly-free. While many familiar lattice anomalies have finite order, perturbative anomalies in the continuum—those captured by Feynman diagrams—have infinite order. In this talk, we show that the Onsager symmetry, a lattice realization of the chiral symmetry of a 1+1d massless Dirac fermion, has an order-two anomaly.

However, imposing lattice CPT symmetry enhances this anomaly from order two to infinite order, yielding a lattice chiral symmetry structure that more faithfully matches the continuum chiral anomaly. (This talk is based on arXiv:2606.12510 with Elijah Lew-Smith and Shu-Heng Shao.)