On unitarity relations and their application to meson-antimeson mixing

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

Test of superposition

Starting with a C-odd state [for example, phi, UPSILON(4S)] made out of a neutral flavored meson f and its antiparticle fBAR, the probability for producing the state ff has the same double time dependence as the corresponding probability for producing the state fBAR fBAR

Testing reciprocity and CPT-invariance for neutral kaons

We point out that the time-reversal-invariant explanation of the recently observed CPLEAR asymmetry is valid at the level of less than three standard deviations; this asymmetry has been claimed to be the first direct observation of time-reversal-noninvariance in the neutral kaon system. We note how, by avoiding the assumptions made at present, future data may provide model-independent tests of structural T- and CPT-invariances of the neutral kaon complex

Nature of direct cp violation in k0-]pi-pi decays

Galic's relation between (phi+- - phi(00)) and \ eta(00)/eta+- \ is generalized to include possible CPT noninvariance. Future data can improve the limits on the CPT-noninvariant contributions that are allowed at present

Toward an experimental determination of possible vacuum regeneration for neutral flavoured mesons

The usual phenomenology of the complex formed by a neutral flavoured meson M-0 and its antiparticle (M) over bar (0) assumes the absence of vacuum regeneration in this complex. We propose experiments for determining the two amplitudes of (possibly non-zero) vacuum regeneration: (i) a comparison of the time dependence of decays of the M-0 and (M) over bar (0) into a channel which could be a CP-eigenstate (e-g., pi(+)pi(-) or pi(0)pi(0)pi(0)), or a general channel like pi/nu; (ii) a measurement of the ratio of the time-dependent transmutations, (M-0 --> (M) over bar (0)) and ((M) over bar (0) --> M-0); (iii) a measurement of the ratio of the time-dependent probabilities for the production of \(MM0)-M-0> and \(M) over bar (0)(M) over bar (0)> states, starting with a C-odd correlated \(M) over bar (0)(M) over bar (0)> state like the phi-meson. The proposed experiments are required to be as accurate as those for the known CP-violation effects in the (M-0, (M) over bar (0)) complex

ON NEUTRINO AND ANTI-NEUTRINO SCATTERING BY ELECTRONS, AND BY PARTONS

Assuming a non-derivative point interaction, and Born approximation, there are some simple relations between neutrino and antineutrino scattering on electrons or partons. They have been observed already, for some special cases, in the results of explicit calculations. Here they are obtained from simple and general considerations. (8 refs)