Journal of High Energy Physics

, 2019:223 | Cite as

Trace anomaly for chiral fermions via Hadamard subtraction

  • Markus B. FröbEmail author
  • Jochen Zahn
Open Access
Regular Article - Theoretical Physics


We calculate the trace (conformal) anomaly for chiral fermions in a general curved background using Hadamard subtraction. While in intermediate steps of the calculation imaginary terms proportional to the Pontryagin density appear, imposing a vanishing divergence of the stress tensor these terms completely cancel, and we recover the well- known result equal to half the trace anomaly of a Dirac fermion. We elaborate in detail on the advantages of the Hadamard method for the general definition of composite operators in general curved spacetimes, and speculate on possible causes for the appearance of the Pontryagin density in other calculations.


Anomalies in Field and String Theories Conformal and W Symmetry 


Open Access

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© The Author(s) 2019

Authors and Affiliations

  1. 1.Institut für Theoretische PhysikUniversität LeipzigLeipzigGermany

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