The Universal Extra Dimensional Model with $S^2/Z_2$ extra-space

TL;DR

This paper introduces a six-dimensional Universal Extra Dimensional model on an $S^2/Z_2$ orbifold, detailing its field content, boundary conditions, and KK mode spectrum, with implications for dark matter stability.

Contribution

It presents a novel 6D UED model on an $S^2/Z_2$ orbifold with specific gauge symmetry, boundary conditions, and KK spectrum analysis, including dark matter candidate stability.

Findings

Lightest KK particles are the first KK modes of massless gauge bosons.

The model ensures the stability of the lightest KK particle due to KK parity.

Mass spectrum derived from KK mode expansion confirms phenomenological viability.

Abstract

We propose a new Universal Extra Dimensional model that is defined on a six-dimensional spacetime which has a two-sphere orbifold $S^2/Z_2$ as an extra-space. We specify our model by choosing the gauge symmetry as SU(3)$\timesSU(2)\timesU(1)_Y \timesU(1)_X$, introducing field contents in six-dimensions as their zero modes correspond to the Standard model particles, and determining a boundary condition of these fields on orbifold $S^2/Z_2$. A background gauge field that belongs to U(1)$_X$ is introduced there, which is necessary to obtain massless chiral fermions in four-dimensional spacetime. We then analyze Kaluza-Klein(KK) mode expansion of the fields in our model and derive the mass spectrum of the KK particles. We find that the lightest KK particles are the 1st KK particle of massless gauge bosons at tree level. We also discuss the KK parity of the KK modes in our model and confirm the stability of the lightest KK particle which is important for dark matter physics.