CP symmetry and its violation

Article By:

Quinn, Helen R. Retired, Stanford Linear Accelerator Center, Menlo Park, California.

Greljo, Admir Theoretical Physics Department, CERN, Geneva, Switzerland.

Last reviewed:December 2019

DOI:https://doi.org/10.1036/1097-8542.166177

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• CP symmetry and its violation, published January 2003:Download PDF Get Adobe Acrobat Reader

The particle physics principle that physical laws should remain unchanged when replacing matter with antimatter in point reflection of space, and the observations that this symmetry is violated in some rare processes involving the weak nuclear force. CP symmetry is the technical name for an almost, but not quite, exact symmetry of the laws of physics (Fig. 1). It is the symmetry between the laws of physics for matter and those for antimatter. CP violation refers to the very small effects showing that this symmetry is not exact. The symmetry appears to be exact for three out of the four fundamental interactions, or forces of nature, namely the strong, electromagnetic, and gravitational interactions. Only in a few weak interaction processes is any violation of this symmetry found. See also: Antimatter; Electromagnetism; Fundamental interactions; Gravity; Matter; Strong nuclear interactions; Weak nuclear interactions

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