Randall-Sundrum and strings

Abstract

We investigate stringy excitations in Randall-Sundrum effective theories for electroweak symmetry breaking arising from embedding in string theory. RS is dual to a confining gauge theory, which we expect to have "QCD strings," or color flux tubes. Stringy constructions of RS-like theories allow us to investigate the mass of these string states, which typically grows with a small fractional power of the number of colors N of the dual gauge theory. There are two known strong constraints on N for RS-like theories. The first arises from demanding that the Standard Model gauge couplings do not have a Landau pole at low scales. The second arises from demanding that the first-order confining phase transition in the early universe is able to proceed without leaving an empty universe, i.e. that the rate of bubble nucleation is not too small. We find that these constraints on N imply that string states are generically at most a factor of a few heavier than the lightest KK states, and we cannot selfconsistently remain in the limit N, λ 1. We examine various string constructions of AdS or RS-like backgrounds, including orbifolds, theories on M5-branes, theories on D4-branes, and the recent F-theory construction of Polchinski and Silverstein. In every case we find that there are strong bounds on the mass of new stringy states. We briefly discuss important phenomenological implications due to the presence of such light stringy excitations, such as precision electroweak and flavor observables, as well as collider signals.

Fermion localization in higher curvature spacetime

“…Such moduli can be stabilized by fluxes. In our model, which is similar to a 5-dimensional Randall-Sundrum (RS) model, it is assumed that these degrees of freedom are frozen to their Vacuum expectation value (VEV) and are nondynamical at the energy scale under consideration [27]. We therefore focus into the slice of AdS 5 as is done for the 5-dimensional RS model.…”

“…This is exactly equivalent to the similar effect if we set c 2 = 0 from the strating point of our computation. In this case Eq (2.25) can be written as: 27) and consequently the modified constraint condition to solve the naturalness or gauge hierarchy problem can be recast at the orbifold point y = π as:…”

Modulus stabilization in higher curvature dilaton gravity

“…VEV and are non-dynamical at the energy scale under consideration [66]. We therefore focus into the slice of AdS 5 as is done for the 5-dimensional RS model.…”

Effective AdS/renormalized CFT

“…It is still unclear whether pure AdS effective theories as the low-energy descriptions are generic or not and whether they would always have UV completions. For phenomenological implications of (nondecoupled) internal dimensions, see [43].…”