CP-symmetry

CP-symmetry is a symmetry obtained by a combination of the C-symmetry and the P-symmetry. When it was found that both these symmetries were violated individually, it looked plausible that a combination of the two would be preserved by all physical laws. Simply stated, the preservation of CP-symmetry by all physical phenomena would mean that all physical laws preserve form when a charge-inversion transformation (positive to negative and vice-versa inversion of electric charges) and a parity-inversion transformation ('left' to 'right' and vice versa; inversion; or, simply the reversal of the coordinate axis in a Cartesian coordinate system used to describe the system under consideration) are done simultaneously. But to the dismay of physicists, it was discovered in 1964 by the group of Cristenson, Cronin, Fitch and Turlay in a kaon decay experiment that this symmetry too was violated, and only a weaker version of the symmetry could be preserved by physical phenomena, which was CPT-symmetry. Because of the CPT-symmetry, a violation of the CP-symmetry is equivalent to a violation of the T-symmetry.

References

• Branco, G. C. and Lavoura, L. and Silva, J. P., CP violation. Clarendon Press, Oxford (1999). ISBN 0-198-50399-7.
• Bigi, I. and Sanda, A., CP violation. Cambridge University Press (1999). ISBN 0-521-44349-0.
• {{Book reference | Author=Griffiths, David J. | Title=Introduction to Elementary Particles | Publisher=Wiley, John & Sons, Inc | Year=1987 | ID=ISBN 0471603864}}