A self-tuning mechanism in (3+p)d gravity-scalar theory

Eun Kyung Park; Pyung Seong Kwon

doi:10.1088/1126-6708/2007/11/051

paper

A self-tuning mechanism in (3+p)d gravity-scalar theory

arXiv:hep-th/0702171 · doi:10.1088/1126-6708/2007/11/051

Abstract

We present a new type of self-tuning mechanism for ( $3 + p$ )d brane world models in the framework of gravity-scalar theory. This new type of self-tuning mechanism exhibits a remarkable feature. In the limit $g_{s} \to 0$ , $g_{s}$ being the string coupling, the geometry of bulk spacetime remains virtually unchanged by an introduction of the Standard Model(SM)-brane, and consequently it is virtually unaffected by quantum fluctuations of SM fields with support on the SM-brane. Such a feature can be obtained by introducing Neveu-Schwarz(NS)-brane as a background brane on which our SM-brane is to be set. Indeed, field equations naturally suggest the existence of the background NS-brane. Among the given such models, of the most interest is the case with $Λ = 0$ , where $Λ$ represents the bulk cosmological constant. This model contains a pair of coincident branes (of the SM- and the NS-branes), one of which is a codimension-2 brane placed at the origin of 2d transverse space ( $\equiv Σ_{2}$ ), another a codimension-1 brane placed at the edge of $Σ_{2}$ . These two branes are (anti) T-duals of each other, and one of them may be identified as our SM-brane plus the background NS-brane. In the presence of the background NS-brane (and in the absence of $Λ$ ), the 2d transverse space $Σ_{2}$ becomes an orbifold $R_{2} / Z_{n}$ with an appropriate deficit angle. But this is only possible if the ( $3 + p$ )d Planck scale $M_{3 + p}$ and the string scale $M_{s}$ ( $\equiv 1/ α^{'}$ ) are of the same order, which accords with the hierarchy assumption \cite{1,2,3} that the electroweak scale $m_{E W}$ is the only short distance scale existing in nature.

A self-tuning mechanism in (3+p)d gravity-scalar theory

Abstract

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