Fermion traces without evanescence

Nikolai Zerf (Institut für Physik, Humboldt-Universität zu Berlin, Netwonstraße 15 D-12489 Berlin, Germany)

We outline the evaluation of n-dimensional fermion traces (nN) built by products of Dirac-γ matrices suitable for a uniform dimensional continuation. Such a continuation is needed for calculations employing a dimensional regulator whenever intrinsically integer dimensional tensors yield nonvanishing contributions. A prime example for such a tensor is given by γ5 for n=4. The main difference between dimensional regularization (DREG) and a dimensionally continued regularization (DCREG) is that DCREG does not attempt to lift the algebra to continuous d dimensions (dR). As a consequence one has to properly deal with evanescent structures in order to ensure the uniform application of the regulator. In basic steps we identify evanescent structures in fermion traces and show that their proper treatment is crucial for example when calculating the VVA anomaly in four dimensions. We checked that the performed considerations enable the evaluation of Standard Model Z factors within DCREG up to including three loops.

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      "source": "APS", 
      "value": "We outline the evaluation of <math><mi>n</mi></math>-dimensional fermion traces (<math><mi>n</mi><mo>\u2208</mo><mi>N</mi></math>) built by products of Dirac-<math><mi>\u03b3</mi></math> matrices suitable for a uniform dimensional continuation. Such a continuation is needed for calculations employing a dimensional regulator whenever intrinsically integer dimensional tensors yield nonvanishing contributions. A prime example for such a tensor is given by <math><msub><mi>\u03b3</mi><mn>5</mn></msub></math> for <math><mi>n</mi><mo>=</mo><mn>4</mn></math>. The main difference between dimensional regularization (DREG) and a dimensionally continued regularization (DCREG) is that DCREG does not attempt to lift the algebra to continuous <math><mi>d</mi></math> dimensions (<math><mi>d</mi><mo>\u2208</mo><mi>R</mi></math>). As a consequence one has to properly deal with evanescent structures in order to ensure the uniform application of the regulator. In basic steps we identify evanescent structures in fermion traces and show that their proper treatment is crucial for example when calculating the <math><mi>V</mi><mi>V</mi><mi>A</mi></math> anomaly in four dimensions. We checked that the performed considerations enable the evaluation of Standard Model <math><mi>Z</mi></math> factors within DCREG up to including three loops."
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Published on:
05 February 2020
Publisher:
APS
Published in:
Physical Review D , Volume 101 (2020)
Issue 3
DOI:
https://doi.org/10.1103/PhysRevD.101.036002
arXiv:
1911.06345
Copyrights:
Published by the American Physical Society
Licence:
CC-BY-4.0

Fulltext files: