1. Extra Dimensions

6. 卡拉比-丘成桐空间
超弦理论的额外维

7. (1) Kaluza-Klein Theory (1921, 1926)
Use a five-dimensional spacetime to unify gravitation and electromagnetism

8. Kaluza–Klein tower Infinite tower of 4D fields with masses:4D 5D
Infinite tower of 4D fields with masses:
These new particles: Kaluza Klein (KK) modes

9. Large Extra Dimensions
ADD model (1998)

10. Universal Extra Dimensions
Appelquist, Cheng, Dobrescu (2000)
All fields propagate universally in the extra dimensions
The universal extra dimensions are compactified with radii much larger than the traditional Planck length, although smaller than in the ADD model
LHC bounds on compactification scale of one or two universal extra dimensions are about 1 TeV

11. Dark Matter in UED
暗物质湮灭

12. Warped Extra Dimensions
Randall, Sundrum (1999)