Gespeichert in:
| Hauptverfasser: | , , , , |
|---|---|
| Format: | Preprint |
| Veröffentlicht: |
2025
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| Schlagworte: | |
| Online-Zugang: | https://arxiv.org/abs/2502.14500 |
| Tags: |
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Inhaltsangabe:
- We study the renormalization of the QCD $θ$ angle at the two-loop level focusing on divergent and finite $CP$-violating contributions from evanescent operators, using dimensional regularization with the BMHV scheme. When one considers the Lagrangian in $d$-dimensional space-time instead of four dimensions in dimensional regularization, evanescent operators that break the chiral symmetry are induced. Consequently, $T$-odd and $P$-odd fermion loops in the BMHV scheme generate evanescent contributions to the QCD $θ$ angle. We carefully classify the evanescent contributions into two types: one originating from the evanescent operators at the one-loop level and the other directly produced by two-loop calculations. We show that renormalization of the parameters in the BMHV scheme keeps removing those unphysical contributions to the QCD $θ$ angle at any scale at the two-loop level. We also discuss how the rephasing invariance of the radiative correction to the QCD $θ$ angle is realized in the BMHV scheme.