# Large Star/Rose Extra Dimension with Small Leaves/Petals

- Authors
- Publication Date
- Feb 11, 2020
- Source
- HAL-ENAC
- Keywords
- Language
- English
- License
- Unknown
- External links

## Abstract

Scenarii with Large Extra Dimensions (LEDs) compactified on a ($q \leq 7$)D torus and with the Standard Model (SM) fields localized on a 3-brane reformulate the gauge hierarchy problem between the 4D Planck scale $\Lambda_P^{(4)} \sim 10^{18}$ GeV and the electroweak scale $\Lambda_{EW} \sim 100$ GeV as a geometrical hierarchy problem: gravity is strongly coupled at the $(4+q)D$ Planck scale $\Lambda_P^{(4+q)} \sim \mathcal{O}(1)$ TeV, but the compactification radii need to be stabilized at large values compared to the $(4+q)$D Planck length $1/\Lambda_P^{(4+q)}$. In this article, we propose to compactify a single LED on a star/rose graph with a large number of identical leaves/petals of length/circumference of $\mathcal{O}(1/\Lambda_{EW})$, where the 5D Planck scale is $\Lambda_P^{(5)} \sim \mathcal{O}(1)$ TeV (without a large geometrical hierarchy to stabilize). The 4D SM fields are localized at the central vertex of the star/rose graph. We predict a feebly coupled tower of KK-gravitons invisible in current experiments with a KK scale of $\mathcal{O}(\Lambda_{EW})$. Our scenarii lead also to TeV scale strongly coupled gravitational phenomena and to an infinite tower of trans-TeV semi-classical black holes. If there is a stable black hole remnant after evaporation, the Planckion, it could constitute a part of dark matter. Moreover, we propose a toy model to generate light Dirac neutrinos, where the right-handed neutrinos are KK modes of gauge singlet fermions propagating in the extra dimension. In our models, a large number of KK-gravitons and of sterile KK-neutrinos interact only with gravity and constitute a hidden sector.