In
particle physics, models with universal extra dimensions include one or more spatial dimensions beyond the three spatial and one temporal dimensions that are observed.
Overview
Models with universal extra dimensions, studied in 2001 assume that all fields propagate universally in the extra dimensions; in contrast, the
ADD model
In particle physics and string theory (M-theory), the ADD model, also known as the model with large extra dimensions (LED), is a model framework that attempts to solve the hierarchy problem. (''Why is the force of gravity so weak compared to the e ...
requires that the fields of the
Standard Model be confined to a four-dimensional membrane, while only gravity propagates in the extra dimensions.
The universal extra dimensions are assumed to be compactified with radii much larger than the traditional Planck length, although smaller than in the ADD model, ~10
−18 m. Generically, the—so far unobserved—Kaluza–Klein resonances of the Standard Model fields in such a theory would appear at an energy scale that is directly related to the inverse size ("compactification scale") of the extra dimension,
The experimental bounds (based on
Large Hadron Collider
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundre ...
data) on the compactification scale of one or two universal extra dimensions are about 1 TeV.
[
]
Other bounds come from
electroweak precision measurements at the Z pole, the muon's magnetic moment, and limits on flavor-changing neutral currents, and reach several hundred GeV. Using universal extra dimensions to explain dark matter yields an upper limit on the compactification scale of several TeV.
See also
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Large extra dimension
In particle physics and string theory (M-theory), the ADD model, also known as the model with large extra dimensions (LED), is a model framework that attempts to solve the hierarchy problem. (''Why is the force of gravity so weak compared to the e ...
s
*
Kaluza–Klein theory
*
Randall–Sundrum model
Notes
References
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{{DEFAULTSORT:Universal Extra Dimension
Particle physics
Physics beyond the Standard Model