Disentangling violations ofCPTfrom other new-physics effects

Abstract

We analyze the prospects for observing CPT violation using neutralmeson P 0 -P 0 systems. Before one can claim a measurement of CPT violation, one must be able to rule out the possibility that its result is due to simpler new-physics effects. In particular, one must be able to separate the CPT-violating quantities from parameters violating the ∆P = ∆Q rule of semileptonic decays, and from new-physics contributions to the production mechanism of the neutral mesons. One can isolate CPT violation using the semileptonic decays of single, tagged neutral mesons; unfortunately, this situation cannot be implemented at the Υ(4S). For P 0 P 0 pairs produced in a correlated parity-odd state we show that, by combining the di-lepton with the single-lepton decays, it is in principle possible to extract unambiguously one CPT-violating parameter. Finally, we develop the formalism necessary for describing new-physics effects in the production mechanism; this includes both cascade decays and violations of the rule of associated production.

Testing CPT invariance by using C-even neutral-meson-antimeson correlated states

“…[10]. It has recently been shown [7] that it is difficult or even impossible to extract θ from experiments with states of the experimentally preferred form |M − alone. This happens because, in the semileptonic decays of |M − , the effects of CPT noninvariance are entangled with those of violations of the ∆F = ∆Q rule-where F means flavour, i.e., F may be either S, C, or B.…”

“…We shall use the simple notation + for f and − for g. We want to show that, in this particular case, it is possible, at least in principle, to explicitly derive the value of θ from the observation of the time dependence of R A . Allowing for transitions which violate the ∆F = ∆Q rule, we introduce the rephasing-invariant quantities [7] λ + = q pĀ…”

Tests of CPT invariance for neutral flavored meson-antimeson mixing

“…[21] considers semileptonic decays of tagged K 0 andK 0 with X = π − . Using the convenient notation R + (t) for having M 0 at t = 0 decaying semileptonically into ℓ + , etc., one obtains [9] …”

“…In Section IV we summarize, for reference and comparison, decays of single M 0 andM 0 mesons, which have been extensively investigated; see, e.g., Ref. [9]. In Section V, the twotime transitions of the C-even and C-odd correlated…”

“…One may note that it is important to allow new physics through violations of the ∆F = ∆Q rule if one is looking for new physics through CPT violation, especially because of the similarity [9,10] of the effects of these two types of violations. Let us briefly mention some tagging methods.…”