Lisa Randall - Extra Dimensional Particle Resonances at the LHC (1/3)





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Published on Sep 17, 2012

Professor Lisa Randall, professor of physics at Harvard University, explains some of her theoretical models on extra-dimensional, warped spacetime to theoretical and experimental physicists at CERN and how, by using the Large Hadron Collider, physicists may soon be able to probe into higher dimensional resonances of particles, predicted by 5D Kaluza-Klein Theory, and even the Dilaton's which may exist and are predictions of the S-Duals in 11D M-Theory.

Stephen Hawking has also made similar claims, while also stating that cosmological studies done on data from the new Planck Satellite mapping the Cosmic Microwave background may also confirm predictions of M-Theory.

This talk will focus on the Kaluza-Klein mode of the Graviton, the particle which exchanges the gravitational force on a quantum scale. Such a particle has been more than a missing link in the Standard Model, its absence was responsible for having no description of gravity in the realm of quantum mechanics and required the development of M-Theory to fully recognise the function gravity must play in black holes and at the Big Bang. In whatever context the graviton itself may exist, we cannot observe it without building a collider the size of a galaxy, however Kaluza-Klein theory predicts resonances of the Graviton that can be accessible near our own brane world described by M-Theory.

With The discovery of the Higgs Boson, physicists will be able to confirm if Supersymmetry is observable at LHC energies by studying the digamma decay mode for a discrepancy against the current Standard Model. If the cross-section of the 2 gamma rays emitted in a Higgs decay show a large disagreement with standard model results, then there may be Supersymmetric particles interacting with the Higgs. This may be observed when the LHC is at full operational power in 2015.

Along with Supersymmetric particles coupling with the Higgs, certain particles predicted by Kaluza-Klein Theory include the scalar field Radion, or Radigraviton, a light particle which couples with the graviton and has the same decay patterns as a Higgs Boson.
Moreover, since in the 5D brane rescales the mass scale of particles, giving them mass in the TeV scale, due to momentum being carried in this brane.

Gravity in our dimension is a very weak interaction, and has 1/Planck scaled interactions. However in warped dimensions the gravitational interaction is strengthened by 16 orders of magnitude stronger, as the Kaluza-Klein partner to the graviton scales as 1/TeV scaled interactions.

Space-Time warping in higher dimensions lowers mass scales for observed particles, pure Standard Model Gravitons would be of huge mass scales, impossible to reach using human technology.

However, near the brane, higher dimensional partners of the graviton would carry its momentum in a 5D brane and would have a rescaled, much lower mass.
Gravitons could therefore be generated by the LHC at certain, as of yet, unknown energy modes. Several modes may exist and oscillate at higher dimension modes which may lie outside the LHC energies at some point, as it passes the 5D brane outside the bulk space.
Hence, if the LHC does have sufficient energy to reach one of the KK-mode graviton modes then it could be possible to detect Quantum Gravity at the LHC.

Higher modes may also allow artificial black holes to be condensed out of higher fluxes of KK-mode gravitons.
These black holes may only consist of a few, fermionic states of supersymmetric gravitons at the lowest energy state so it would instantly be destroyed by the Hawking Process. This would be a huge leap forward into studying M-Theory.

Lisa Randall is an American theoretical physicist and a leading expert on particle physics and cosmology. She works on several of the competing models of string theory in the quest to explain the fabric of the universe.


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