Warping, extra dimensions, and a slice of AdS d

2012

The phenomenological implications of allowing the Higgs to propagate in both AdS 5 and a class of asymptotically AdS spaces are considered. Without tuning, the vacuum expectation value (VEV) of the Higgs is peaked towards the IR tip of the space and hence such a scenario still offers a potential resolution to the gauge-hierarchy problem. When the exponent of the Higgs VEV is approximately two and one assumes order one Yukawa couplings, then the fermion Dirac mass term is found to range from ∼ 10 −5 eV to ∼ 200 GeV in approximate agreement with the observed fermion masses. However, this result is sensitive to the exponent of the Higgs VEV, which is a free parameter. This paper offers a number of phenomenological and theoretical motivations for considering an exponent of two to be the optimal value. In particular, the exponent is bounded from below by the Breitenlohner-Freedman bound and the requirement that the dual theory resolves the gauge hierarchy problem. While, in the model considered, if the exponent is too large, electroweak symmetry may not be broken. In addition, the holographic method is used to demonstrate, in generality, that the flatter the Higgs VEV, the smaller the contribution to the electroweak T parameter. In addition, the constraints from a large class of gauge mediated and scalar mediated flavour changing neutral currents, will be at minimal values for flatter Higgs VEVs. Some initial steps are taken to investigate the physical scalar degrees of freedom that arise from a mixing between the W 5 /Z 5 components and the Higgs components.

Section: A2 the Gauge-goldstone Boson Equivalence Theorem Cross Checkmentioning

confidence: 55%

Section: A2 the Gauge-goldstone Boson Equivalence Theorem Cross Checkmentioning

confidence: 99%

See 1 more Smart Citation

The fermion mass hierarchy in models with warped extra dimensions and a bulk Higgs

2012

“…We now move to consider the scalar components of the gauge fields. For more work on gauge scalars in 6D see [38,39] or in D dimensions [22]. Firstly since the mass terms of equations (7) and ( dependant part we take ∂ i (7)−∂ 5 (8) and ∂ i (8)−∂ j (8) to get…”

Section: The Gauge Scalarsmentioning

confidence: 99%

“…The principal motivation for such a choice is that it is one of the simplest extensions to the RS model that allows the investigation of the phenomenological implications of warping the D > 5 additional dimensions and testing the robustness of the 5D phenomenology. Work has already been done looking at the phenomenology of AdS 5 × M δ [20,21] as well as AdS D [22,23,24] and for additional work on 6D RS models see for example [25,26,27,28]. The work very much continues from [29] where it was demonstrated that if the additional spaces are increasingly (decreasingly) warped towards the IR brane then the couplings of KK gauge fields propagating in the bulk will be suppressed (enhanced) relative to the zero mode couplings.…”

Section: Introductionmentioning

confidence: 99%

Reducing constraints in a higher dimensional extension of the Randall and Sundrum model

Huber

2011

In order to investigate the phenomenological implications of warped spaces in more than five dimensions, we consider a 4 + 1 + δ dimensional extension to the Randall and Sundrum model in which the space is warped with respect to a single direction by the presence of an anisotropic bulk cosmological constant. The Einstein equations are solved, giving rise to a range of possible spaces in which the δ additional spaces are warped. Here we consider models in which the gauge fields are free to propagate into such spaces. After carrying out the Kaluza Klein (KK) decomposition of such fields it is found that the KK mass spectrum changes significantly depending on how the δ additional dimensions are warped. We proceed to compute the lower bound on the KK mass scale from electroweak observables for models with a bulk SU (2) × U (1) gauge symmetry and models with a bulk SU (2) R × SU (2) L × U (1) gauge symmetry. It is found that in both cases the most favourable bounds are approximately M KK 2 TeV, corresponding to a mass of the first gauge boson excitation of about 4 − 6 TeV. Hence additional warped dimensions offer a new way of reducing the constraints on the KK scale.

Electroweak constraints on warped geometry in five dimensions and beyond

Huber

2010

Here we consider the tree level corrections to electroweak (EW) observables from standard model (SM) particles propagating in generic warped extra dimensions. The scale of these corrections is found to be dominated by three parameters, the Kaluza-Klein (KK) mass scale, the relative coupling of the KK gauge fields to the Higgs and the relative coupling of the KK gauge fields to fermion zero modes. It is found that 5D spaces that resolve the hierarchy problem through warping typically have large gauge-Higgs coupling. It is also found in D > 5 where the additional dimensions are warped the relative gauge-Higgs coupling scales as a function of the warp factor. If the warp factor of the additional spaces is contracting towards the IR brane, both the relative gauge-Higgs coupling and resulting EW corrections will be large. Conversely EW constraints could be reduced by finding a space where the additional dimension's warp factor is increasing towards the IR brane. We demonstrate that the Klebanov Strassler solution belongs to the former of these possibilities.