SMuK 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

T: Fachverband Teilchenphysik

T 84: Theory EW

T 84.5: Vortrag

Mittwoch, 22. März 2023, 18:30–18:45, HSZ/0204

Two-loop Symmetry Restoration in a Chiral Abelian Gauge Theory in DReg with Non-Anticommuting γ₅ — •Paul Kühler — Institut für Kern- und Teilchenphysik, TU Dresden

Dimensional Regularization is a popular and powerful method for renormalizing gauge theories at the multiloop level. This is due not least of all to the fact that DReg preserves BRST symmetry for vector-like theories such as QCD and QED, which not only guarantees that the renormalized theories make sense as a quantum theory, but it also tremendously simplifies calculations.

This feature is unavoidably lost in the case of chiral theories like the electroweak sector of the SM. Technically, this manifests in inconsistencies arising from insisting on retaining certain relations valid for γ₅ in 4-dimensions in the formal D-dimensional space of DReg. One way out is the BMHV scheme which gives up anti-commutativity and recommends itself by its consistent treatment generalizable to the multiloop setting. BRST symmetry is intermediately broken but may be restored by adding finite, non-invariant counterterms.

In this talk we exemplify our approach to renormalizing chiral gauge theories in the BMHV scheme with the aim of applying it to the SM. Here we present a concrete two-loop calculation of a simple, chiral Abelian model (based on Belusca-Maito et al., JHEP, Vol. 11, 2021; 2109.11042) with its necessary counterterm structure, and we discuss the explicit restoration of well-known Ward identities like transversality of the photon self-energy. In this setting, they are an immediate test of the restoration (or lack thereof) of the classical symmetry.