Standard model on a domain-wall brane?

Abstract

We propose a 4 + 1-dimensional action that is a candidate for realising a standard-model-like effective theory for fields dynamically localised to a domain-wall brane. Our construction is in part based on the conjecture that the Dvali-Shifman mechanism for dynamically localising gauge bosons to a domain wall works correctly in 4 + 1-d. Assuming this to be so, we require the gauge symmetry to be SU(5) in the bulk, spontaneously breaking to SU(3)⊗SU(2)⊗U(1) inside the domain wall, thus dynamically localising the standard model gauge bosons provided that the SU(5) theory in the bulk exhibits confinement. The wall is created jointly by a real singlet-Higgs field η configured as a kink, and an SU(5) adjoint-Higgs field χ that takes nonzero values inside the wall. Chiral 3 + 1dimensional quarks and leptons are confined and split along the bulk direction via their Yukawa couplings to η and χ. The Higgs doublet and its colour triplet SU(5) partner are similarly localised and split. The splittings can suppress coloured-Higgs-induced proton decay and, because of the different localisation profiles, the usual SU(5) mass relation me = m d does not arise. Localised gravity is generated via the Randall-Sundrum alternative to compactification.

SO(10) domain-wall brane models

“…III that we need a hierarchical ordering of the inherent physical scales for our model to work. Both these points were discussed in the DGV paper [12]. However in going from SU(5) to SO(10) gauge invariance in the bulk we have introduced a new intermediate symmetrybreaking scale.…”

“…We have also included the spin connections to ensure the derivative is covariant under Lorentz transformations. With a metric-geometry described by (12) the fermionic terms in the action must be rewritten in terms of the vielbeins and spin connections…”

“…Recently, one of the authors (RRV), proposed, together with Davies and George, a specific theory (to be called the DGV model hereinafter) that may realize the dynamical localization of an SUð3Þ C Â SUð2Þ W Â Uð1Þ Y gauge theory plus gravity to a solitonic domain-wall brane with one warped extra dimension [12]. The DGV paper speculates that Dvali-Shifman gauge field localization (to be reviewed in a later section) is implemented by confining SUð5Þ bulk gauge dynamics.…”

Scalar kinks in warped extra dimensions

“…In the context of extra dimensions, these kinklike scalar backgrounds can be used, for example, to localize bulk fermions near either boundary [34][35][36][37], allowing for interesting constructions of flavor models. They can also affect the localization of other scalar or vector fields leading to a field theoretic description of fat branes (see, for example, the constructions in [38][39][40][41]). More recently, multiple bulk scalar fields have been used to construct so-called soft-wall models, in which the profiles of the scalar fields, coupled to the gravitational background, play the role of a dynamical IR boundary (as opposed to a hard-wall IR boundary or brane, located at a specific location in the IR).…”

Domain Walls and Gauge Field Localization in Strongly-Coupled Pure Yang-Mills Theories

“…We hope to present generalization to higher dimensions and localized non-Abelian fields in future publications. Having such an explicit field-theoretic mechanism would greatly advance more detailed studies of various interesting domain wall based higher-dimensional models [9,10].…”