In
particle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and ...
, 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
The Standard Model of particle physics is the theory describing three of the four known fundamental forces ( electromagnetic, weak and strong interactions - excluding gravity) in the universe and classifying all known elementary particles. I ...
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 hundr ...
data) on the compactification scale of one or two universal extra dimensions are about 1 TeV.
[
]
Other bounds come from
electroweak
In particle physics, the electroweak interaction or electroweak force is the unified description of two of the four known fundamental interactions of nature: electromagnetism and the weak interaction. Although these two forces appear very differe ...
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
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Kaluza–Klein theory
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Randall–Sundrum model
In physics, Randall–Sundrum models (also called 5-dimensional warped geometry theory) are models that describe the world in terms of a warped-geometry higher-dimensional universe, or more concretely as a 5-dimensional anti-de Sitter space where ...
Notes
References
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{{DEFAULTSORT:Universal Extra Dimension
Particle physics
Physics beyond the Standard Model