Charge conjugation-parity-time

Whereas energy appears to be distributed almost continuously, compared to matter, the distribution of matter presents the more tractable problem. When delving into the nature of matter, in its most elementary state, it is encountered in two antagonistic forms with equal probability. These two forms, called matter and anti-matter are best considered as the complementary forms of elementary stuff in two symmetry-related modes of existence. Symmetry-related units of matter and antimatter have the same mass but opposite electric charges and behave in opposite sense with respect to time. This relationship obeys the dictates of what is probably the most fundamental symmetry in Nature, known as CPT (charge conjugation-parity-time inversion) symmetry. Wherever it has been investigated, all natural phenomena have been found to obey CPT symmetry without exception. 

The Estonian academician G.I. Naan (1964), on the basis of the Bohr-Liiders (1954) theorem, argued that the universe cannot exist without an element of CPT (Charge conjugation-Parity-Time) inversion symmetry, which implies the co-existence of material and anti-material worlds. Any interaction in the material world must be mirrored in the anti-world, but without direct contact between the two domains. Because of the inversion symmetry all conservation laws are automatically satisfied as invariant, at magnitudes of zero. 

The most comprehensive symmetry that incorporates all of the foregoing is best known by the acronym CPT (charge conjugation - parity - time). Its most stringent demand is an exact balance between the matter and antimatter of the universe. 

Empirical evidence at variance with standard cosmology is, likewise, totally ignored. Even the most fundamental of empirical observations, known as universal CPT (charge conjugation-parity-time inversion) symmetry, which dictates equal amounts of matter and antimatter in the cosmos, is dismissed out-of-hand. Less well known, but of equal importance, cosmic self-similarity, is not considered at all. 

Like any other great idea, the symmetry principle should be used with circumspection lest the need of enquiry beyond the search for symmetry is obscured. The hazard lurks therein that nowhere in the world has mathematically precise symmetry ever been encountered. The fundamental symmetries underpinning the laws of Nature, i.e. parity (P), charge conjugation (C), and time inversion (T), are hence no more than local approximations and, although the minor exceptions may be just about undetectable, they cannot be ignored2. 

The space-time symmetry underlying the Lewis model requires further analysis. It has often been speculated that the known universe is one of a pair of symmetry-related worlds. Naan argued forcefully [105] that an element of PCT (Parity-Charge conjugation-Time inversion) symmetry within the universal structure is indispensible to ensure existence. The implication is co-existence of material and anti-material worlds in an unspecified symmetric arrangement. Hence any interaction in the material world must be mirrored in the anti-world and it will be shown that this accords with the suggested mechanism of interaction. 

The weak interactions that cause atomic PNC violate not only the symmetry of parity, P, but also the symmetry of charge conjugation, C. However, the product of these, CP, is conserved. Because any quantum field theory conserves CPT, where T is time reversal this is equivalent to saying that T is conserved. However, even this symmetry is known to be violated. To date, this incompletely understood phenomenon has been seen in only two systems, the neutral kaon system, and, quite recently, the neutral B meson system. However, as noted already in the 1950 s by Ramsey and Purcell [62], an elementary particle possessing an intrinsic electric dipole moment also violates T invariance, so that detection of such a moment would be a third way of seeing T noninvariance. 

Here also, then, a very small initial asymmetry led seemingly to a complete dominance of the normal matter present today. The exact origin of the cosmic asymmetry is not known [14]. However, we know a small fundamental asymmetry in the so-called charge conjugation (C) and also in the combination CP of charge conjugation with parity (P). Hypotheses exist, which make this fundamental asymmetry responsible for the nearly complete asymmetry observed in the cosmos today, but their validity is doubtful. This question, thus, also remains open at the time. We shall address these symmetries in more detail below. 

CP invariance The symmetry generated by the combined operation of changing charge conjugation (Q and parity (P). CP violation occurs in weak interactions in kaon decay and in B-mesons. See also CPT theorem time reversal. 

The conclusion of these works is that the parity (P) invariance and, separately, the charge conjugation (C) invariance are violated in P decay, while the time reversal (T) or combined CP invariance is not. The parity non-invariance (i.e., non-invariance of the Hamiltonian of the weak interaction under space reflection) can be expressed alternativelyby saying that the parity is not conserved. This formulation is a consequence of the fact that the parity P is an observable quantity. The presence of two-pion decay mode in the K° kaon decay implies, however, that even the CP invariance is violated in the weak interaction (Christenson et al. 1964). 

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