Two examples of rare K+-decays in emulsion

Rare K Decays ∗

The rare decays of the K meson have had a long tradition as a laboratory for testing the symmetry properties of the weak interactions, and the manner in which these symmetries are broken by higher order effects. Present–day interest is focussed on decays that are suppressed by CP–symmetry or GIM symmetry. Such decays, in the standard theory, are sensitive to effects of the virtual top quark, an...

Rare K- (vs.) B-decays

We present a concise review of the recent theoretical progress concerning the standard model calculations of the rare K L → π 0 ν ¯ ν, K + → π + ν ¯ ν(γ), ¯ B → X s γ, and ¯ B → X s + − decays. The current status and future of the model-independent analysis of rare K-and B-meson decays within constrained minimal-flavor-violation is also briefly discussed. * Speaker. † We thank the organizers fo...

CP Violation in K Decays and Rare Decays ∗

The present status of CP violation in decays of neutral kaons is reviewed. In addition selected rare decays of both K and B mesons are discussed. The emphasis is in particular on observables that can be reliably calculated and thus offer the possibility of clean tests of standard model flavor physics. ∗ Invited Talk presented at the Workshop on Heavy Quarks at Fixed Target, St. Goar, Germany, 3...

Long-distance Effects in Rare K Decays

The rare K decays considered in this talk proceed through Flavor Changing Neutral Currents, arising at loop-level in the Standard Model. What makes them specially interesting is that shortdistance (SD) effects contribute significantly to their decay rates, and that long-distance (LD) hadronic effects are under theoretical control. They are thus ideal to constrain the Standard Model by precise e...

Recent NA48 results on rare K decays