The littlest Higgs in anti-de Sitter space

Abstract

Abstract:We implement the SU(5)/SO(5) littlest Higgs theory in a slice of 5D Antide Sitter space bounded by a UV brane and an IR brane. In this model, there is a bulk SU(5) gauge symmetry that is broken to SO(5) on the IR brane, and the Higgs boson is contained in the Goldstones from this breaking. All of the interactions on the IR brane preserve the global symmetries that protect the Higgs mass, but a radiative potential is generated through loops that stretch to the UV brane where there are explicit SU(5) violating boundary conditions. Like the original littlest Higgs, this model exhibits collective breaking in that two interactions must be turned on in order to generate a Higgs potential. In AdS space, however, collective breaking does not appear in coupling constants directly but rather in the choice of UV brane boundary conditions. We match this AdS construction to the known low energy structure of the littlest Higgs and comment on some of the tensions inherent in the AdS construction. We calculate the 5D Coleman-Weinberg effective potential for the Higgs and find that collective breaking is manifest. In a simplified model with only the SU(2) gauge structure and the top quark, the physical Higgs mass can be of order 200 GeV with no considerable fine tuning (25%). We sketch a more realistic model involving the entire gauge and fermion structure that also implements T -parity, and we comment on the tension between T -parity and flavor structure.

Little M-theory

“…On the other hand, without the floating fermions, we know of no way to implement minimal flavor violation in the T -symmetric limit. This tension between T -parity, flavor structure, and theory space locality has been observed before [51], and is probably a generic issue for composite Higgs theories. We will now write down all couplings local in theory space as well as the leading nonlocal interaction.…”

Composite Higgses

“…For instance, due to constraints from electroweak precision constraints, which affect more significantly the boson sector of little Higgs models, it is known that it is favored not to extend the SM gauge group, at the expense of a collective symmetry breaking in the gauge sector that resembles that of holographic models. This set-up was first proposed in [70], and later the littlest Higgs coset SU(5)/SO(5) was realized à la holographic Higgs, first as a warped extra-dimensional model in [71] and then using the 4D effective description [72].…”

Colorful Twisted Top Partners and Partnerium at the LHC

“…(17). As long as the fermions have Neumann boundary conditions on the SU(3) Gpreserving brane, violations of SU(3) G will be suppressed by the inter-brane separation [84,85].…”