Searches for extra dimensions with the ATLAS and CMS detectors

Jan Kretzschmar

doi:10.1016/j.nuclphysbps.2015.09.080

Jan Kretzschmar

Open Access

https://doi.org/10.1016/j.nuclphysbps.2015.09.080

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Abstract

Models with extra spatial dimensions have been proposed to explain the large apparent hierarchy between the Electroweak and Planck scales. Such models predict a host of different new phenomena observable at the energy scale in reach with the LHC. Searches for these phenomena with the full 8 TeV LHC dataset taken with the ATLAS and CMS detectors are presented for different topologies. The exchange of gravitons propagating through the extra dimensions can lead to resonant or non-resonant enhancements in high mass tails. Semi-classical and quantum black holes could form and their decays provide for different spectacular signatures.

Highlights

One of the open questions of modern particle physics is the so-called “Hierarchy problem”
The heaviest particles of the Standard Model, like the W±, Z or Higgs bosons live at the Weak Scale of MEWK = 0.264 TeV, the vacuum expectation value of the Higgs field
Theories with extra dimensions provide a possible solution to the Hierarchy Problem and predict new physics near the Electroweak scale of ∼ 1 TeV

Summary

Introduction

One of the open questions of modern particle physics is the so-called “Hierarchy problem”. The weakness of gravity follows from its propagation through these extra dimensions, making it appear weak in our SM brane These new dimensions obviously need to possess special properties, as the experimental evidence for the four-dimensional space-time is overwhelming at macroscopic length scales. Λπ ∼ MPle−kRπ , reducing the large scale difference by the exponential of a (relatively) small number kR Both of these models make specific predictions for new phenomena observable at the energy scale of the LHC. In the case of the ADD model it is expected, that microscopic black holes should form, once available energy exceeds a certain threshold MThresh, which will be above the (4+n) dimensional Planck scale MD, but typically far below MPl. The phenomenology of the two cases, production close to or far above threshold, must be distinguished.

High mass di-lepton searches

Mono Photons and Mono Jets

Semi-classical Black Holes

Quantum Black Holes

Conclusions