Electroweak Constraints on Minimal Higher-Dimensional Extensions of the Standard Model

TL;DR

This paper investigates how electroweak measurements constrain the size of extra dimensions in minimal 5D extensions of the Standard Model, showing that bounds can be lowered depending on which particles propagate in the extra dimension.

Contribution

It provides a detailed analysis of electroweak constraints on 5D Standard Model extensions, including a consistent quantization method in the $R_\xi$ gauge and explores scenarios with different gauge field propagations.

Findings

Lower bound on compactification scale can be reduced to ~3 TeV.

Constraints depend on which gauge fields propagate in the extra dimension.

Quantization procedure in generalized $R_\xi$ gauge is established.

Abstract

We derive electroweak constraints on the compactification scale of minimal 5-dimensional extensions of the Standard Model, in which all or only some of the SU(2)$_L$ and U(1)$_Y$ gauge fields and Higgs bosons feel the presence of the fifth dimension. In our analysis, we assume that the fermions are always localized on a 3-brane. In this context, we also present the consistent quantization procedure of the higher-dimensional models in the generalized $R_\xi$ gauge. We find that the usually derived lower bound of $\sim 4$ TeV on the compactification scale may be significantly lowered to $\sim 3$ TeV if the SU(2)$_L$ gauge boson is the only particle that propagates in all 5 dimensions.