Abstract

We investigate the regularization-scheme dependent treatment of $\gamma_{5}$ in the framework of dimensional regularization, mainly focusing on the four-dimensional helicity scheme (FDH). Evaluating distinctive examples, we find that for one-loop calculations, the recently proposed four-dimensional formulation (FDF) of the FDH scheme constitutes a viable and efficient alternative compared to more traditional approaches. In addition, we extend the considerations to the two-loop level and compute the pseudo-scalar form factors of quarks and gluons in FDH. We provide the necessary operator renormalization and discuss at a practical level how the complexity of intermediate calculational steps can be reduced in an efficient way.

Highlights

  • The success of quantum-field theoretical predictions over the past decades was enabled, among other things, by the applicability of dimensional regularization as the method provides a mathematically consistent tool to handle ultraviolet (UV) and infrared (IR) divergences in the multi-loop regime

  • Evaluating distinctive examples, we find that for one-loop calculations, the recently proposed four-dimensional formulation (FDF) of the four-dimensional helicity scheme (FDH) scheme constitutes a viable and efficient alternative compared to more traditional approaches

  • From the very moment of the introduction of dimensional regularization in Ref. [1], special attention had to be paid to the treatment of γ5 since the object is closely related to concepts that are only valid in integer dimensions

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Summary

INTRODUCTION

The success of quantum-field theoretical predictions over the past decades was enabled, among other things, by the applicability of dimensional regularization as the method provides a mathematically consistent tool to handle ultraviolet (UV) and infrared (IR) divergences in the multi-loop regime. In a series of publications [2,3,4,5,6,7,8,9,10,11,12,13,14,15] that cover a time span of more than 40 years, different approaches have been developed in order to find consistent rules for the treatment of γ5 in the dimensional framework Irrespective of this effort, in the overwhelming majority of computations that have been performed so far, the original γ5 definition of Ref.

CDR and HV
FDH and DRED
M: ð2:7bÞ
One-loop example 1
FDH and γA5 C
Algebra in genuine four dimensions—FDF
One-loop example 2
Z 2 ddk ð2πÞd ðk
Comment on Bose symmetry
PSEUDOSCALAR FORM FACTORS IN FDH
Effective Lagrangian
Common definition of the form factors
Form factors with γA5 C
UV RENORMALIZATION
Operator renormalization for γB5 M
Operator renormalization for γA5 C
Type A contributions
Type B contributions
Comparison of BM and AC
UV renormalized form factors
CONCLUSIONS
UV renormalization
IR divergence structure
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