Sponsor:
This work has been supported by the Spanish MINECO research grants FIS2014-57387-C3-3-P; FIS2014-57387-C3-1-P; FIS2017-84440-C2-2-P; FIS2017-84440-C2-1-P, the COST action CA15117 (CANTATA), supported by COST (European Cooperation in Science and Technology), and the Severo Ochoa Program SEV-2014-0398. A. F. is supported by the Severo Ochoa Ph.D. fellowship SEV-2014-0398-16-1 and the European Social Fund.
Project:
Gobierno de España. FIS2014-57387-C3-3-P Gobierno de España. FIS2014-57387-C3-1-P Gobierno de España. FIS2017-84440-C2-2-P Gobierno de España. FIS2017-84440-C2-1-P Gobierno de España. SEV-2014-0398. Gobierno de España. SEV-2014-0398-16-1
We introduce an iterative method to univocally determine the adiabatic expansion of the modes of Dirac fields in spatially homogeneous external backgrounds. We overcome the ambiguities found in previous studies and use this new procedure to improve the adiabatWe introduce an iterative method to univocally determine the adiabatic expansion of the modes of Dirac fields in spatially homogeneous external backgrounds. We overcome the ambiguities found in previous studies and use this new procedure to improve the adiabatic regularization/renormalization scheme. We provide details on the application of the method for Dirac fields living in a four-dimensional Friedmann-Lemaître-Robertson-Walker spacetime with a Yukawa coupling to an external scalar field. We check the consistency of our proposal by working out the conformal anomaly. We also analyze a two-dimensional Dirac field in Minkowski space coupled to a homogeneous electric field and reproduce the known results on the axial anomaly. The adiabatic expansion of the modes given here can be used to properly characterize the allowed physical states of the Dirac fields in the above external backgrounds.[+][-]