U_e(1)--covariant R_\xi--gauge for the two Higgs doublet model

TL;DR

This paper introduces a new covariant gauge for the two Higgs doublet model that simplifies loop calculations by reducing nonphysical vertices and ensures QED-like Ward identities, leveraging BRST symmetry.

Contribution

It presents a novel $U_e(1)$--covariant $R_$ gauge based on BRST symmetry, reducing nonphysical vertices and simplifying loop calculations in the two Higgs doublet model.

Findings

Simplifies loop calculations by removing nonphysical vertices.

Ensures the theory satisfies QED-like Ward identities.

Provides Feynman rules for new and modified vertices.

Abstract

An $U_e(1)$--covariant $R_\xi$ gauge for the two Higgs doublet model based in the BRST symmetry is introduced. This gauge allows one to remove an important number of nonphysical vertices appearing in conventional linear gauges, which greatly simplifies the loop calculations, since the the resultant theory satisfies QED--like Ward identities. The presence of four ghost interactions in this type of gauges and its connection with the BRST symmetry is stressed. The Feynman rules for those new vertices that arise in this gauge, as well as for those couplings already present in the linear $R_\xi$ gauge but that are modified by this gauge--fixing procedure, are presented.