The chiral torsional anomaly and the Nieh-Yan invariant with and without
boundaries
The chiral torsional anomaly and the Nieh-Yan invariant with and without
boundaries
There exists a long-standing debate regarding the torsion contribution to the 4d chiral anomaly of a Dirac fermion. Central to this debate is the Nieh-Yan anomaly, which has been considered ill-defined and a regularization artifact. Using a heat-kernel approach, we examine the relationship between the Dirac operator index, the Nieh-Yan …