This critical review of the Standard-Model-based approaches is given for description of the direct CP violation in the K⁰ ® 2p decays which is characterized by the ratio e'/e. The semiphenomenological analysis of these processes by using bosonized chiral Lagrangians is discussed in detail. The 1/N_c approach and its modifications, the chiral quark model, lattice QCD, and QCD sum rules are under consideration. The analysis of the results obtained by the author of the review and from other papers has shown that contributions of long-distance effects dominate in the description of both DI = 1/2 rule and e'/e. The chiral corrections up to and including O(p⁶) turn out to be very important when taking into account the final-state interactions and isotopical symmetry breaking effects. To verify the SM quantitatively in the direct CP violation, it is necessary to decrease sufficiently the uncertainties of a big number of phenomenological input parameters from the self-consistent analysis of a wide scope of the low-energy meson processes including decays K ® 3p, K ® 2p g, and K ®p e⁺e^-. This requires new experimental data on these processes as well as detailed calculations of their amplitudes with the chiral higher-order corrections.

PDF (836 Kb)