Little String Theory at a TeV

TL;DR

This paper introduces a framework where the string scale and all compact dimensions are at the TeV scale, addressing the hierarchy problem and predicting observable deviations from Einstein's gravity at collider energies.

Contribution

It proposes a novel model with TeV-scale string and compact dimensions, linking weak gravity to a small string coupling and exploring holographic duals for spectrum calculations.

Findings

Standard model gauge couplings are of order one at TeV scale.

Gravity remains weak and negligible at collider energies.

Potential observable deviations from Einstein's gravity, including equivalence principle violations.

Abstract

We propose a framework where the string scale as well as all compact dimensions are at the electroweak scale $\sim$ TeV$^{-1}$. The weakness of gravity is attributed to the small value of the string coupling $g_s \sim 10^{-16}$, presumably a remnant of the dilaton's runaway behavior, suggesting the possibility of a common solution to the hierarchy and dilaton-runaway problems. In spite of the small $g_s$, in type II string theories with gauge interactions localized in the vicinity of NS5-branes, the standard model gauge couplings are of order one and are associated with the sizes of compact dimensions. At a TeV these theories exhibit higher dimensional and stringy behavior. The models are holographically dual to a higher dimensional non-critical string theory and this can be used to compute the experimentally accessible spectrum and self-couplings of the little strings. In spite of the stringy behavior, gravity remains weak and can be ignored at collider energies. The Damour-Polyakov mechanism is an automatic consequence of our scenario and suggests the presence of a massless conformally-coupled scalar, leading to potentially observable deviations from Einstein's theory, including violations of the equivalence principle.