External Inversion , Internal Inversion , and Reflection Invariance

Having in mind that physical systems have different levels of structure we develop the concept of external, internal and total improper Lorentz transformation (space inversion and time reversal). A particle obtained from the ordinary one by the application of internal space inversion or time reversal is generally a different particle. From this point of view the intrinsic parity of a nuclear particle (‘elementary particle’) is in fact the external intrinsic parity, if we take into account the internal structure of a particle. We show that non-conservation of the external parity does not necessarily imply non-invariance of nature under space inversion. The conventional theory of beta-decay can be corrected by including the internal degrees of freedom to become invariant under total space inversion, though not under the external one. Note: This old paper has recently been subjected to considerable interest due to the increasing exploration of the “exact parity model”, “mirror matter” and its possible manifestation in astrophysics. It is not available elsewhere on the Internet, and in the interests of easy access I am posting it on astro-ph. The body of the paper is identical to the published version, except for few minor correction of spelling. Preseent address: J. Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia E-mail: [email protected] International Journal of Theoretical Physics, Vol. 9,No. 4 (1974), pp. 229–244 2