Implications of recent measurements of B meson mixing and ϵ′/ϵK

John Ellis, John S. Hagelin, S. Rudaz, D. D. Wu

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Within the Standard Model, the recent observation of Bd0-Bd0 meson mixing provides a lower bound on the top quark mass which is mt ≳ 50 to 100 GeV, depending on experimental and theoretical uncertainties. Conversely, flavour-conserving neutral-current upper bounds on mt in combination with Bd0-Bd0 mixing provide nontrivial lower bounds on hadronic current matrix elements. The lower bound on mt is only marginally improved by incorporating as a constraint the CP violation ε{lunate}K observed in the K0-K0 mass matrix, which allows, in principle, a determination of all the Kobayashi-Maskawa matrix elements. The preliminary measurement of ε{lunate}′/ε{lunate}K falls comfortably within the range predicted from using these other weak measurements, favouring mt ∼ 100 GeV within large errors. The Standard Model predicts large. Bs0-Bs0 mixing, but small CP-violating effects in both Bd0-Bs0 and Bs0-Bs0 mixing (≲ 0.3%), whereas nonstandard models can give values as large as 6%. We comment on rate K decays such as K+ → π+νν in the light of Bd0-Bd0 mixing. Finally, we review previous phenomenological proposals for the Kobayashi-Maskawa matrix elements and show that they can largely be excluded.

Original languageEnglish (US)
Pages (from-to)205-235
Number of pages31
JournalNuclear Physics, Section B
Issue numberC
StatePublished - 1988


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