On unitarity relations and their application to meson-antimeson mixing

Abstract

In view of the recent observation of nonexponential decay features for a certain quantum-mechanical system, we revisit our earlier study of the small-time behaviour of the meson-antimeson complex wherein the commonly employed Weisskopf-Wigner approximation could be tested, in principle. We find that the experiments for this testing are difficult because of (i) the smallness of the times required for this study, (ii) the high accuracy required for probing the nonleading terms (which distinguish this approximation from the general theory) in the small-time behaviour of the relevant probabilities and (iii) the crude knowledge of the required 'flavour-tagging' procedures, as available at present.