Speaker
Chang-Tse Hsieh
(National Taiwan University)
Description
Conformal invariance typically emerges in critical systems where the correlation length diverges, which is generally the case for Hermitian quantum systems without a spectral gap (in the thermodynamic limit). However, the situation becomes more subtle when Hermiticity is broken. In this talk, I will discuss when a non-Hermitian gapless quantum system can exhibit conformal invariance, focusing on free fermions in 1+1 dimensions. Certain universal characteristics of such systems—including a negative central charge and logarithmic couplings associated with indecomposable Jordan cell structures in the spectrum—are identified and computed in both continuum field theory and lattice formulations.