Phenomenological methods for unitarity triangle angles
نویسنده
چکیده
The Kobayashi-Maskawa model for CP violation [1] passed in a remarkable way its first crucial test in B decays [2] when a large CP asymmetry was measured [3, 4] in B → J/ψKS in agreement with expectations. The virtue of this gold-plated decay mode is the absence of hadronic uncertainties [5, 6] in predicting the mixing induced asymmetry in terms of a fundamental phase parameter β ≡ φ1 of the Standard Model. This opens a new era, in which other CP asymmetries in B and Bs decays ought to be measured in order to test the KM mechanism in an unambiguous way. One would hope that this will lead to a point where deviations from the simple KM framework will be observed. Very optimistically, one is looking forward to signals of new physics [7, 8], possibly exhibited by large deviations from sin 2β in asymmetries for charmless strangeness changing penguin dominated B decays to CP final states, such as φKS, η Ks or K KKS [4]. Moderate deviations from sin 2β are allowed within the KM framework, caused by amplitudes carrying a different weak phase. These amplitudes involve hadronic uncertainties [9]. In order to make a clear case for physics beyond the Standard Model, these effects must be carefully bounded [10, 11] using flavor symmetry arguments and input from experimental data. A systematic study of the CP violating phase structure of weak quark couplings requires a measurement of the phase γ ≡ φ3, associated with CP violation in direct decays. The present uncertainties in this phase and in the phase φ2 ≡ α = π−β−γ, combining γ with the B0−B0 mixing phase β, are about 40 [12], 38 ≤ φ3 ≡ γ ≤ 80 , 78 ≤ φ2 ≡ α ≤ 122 , (1)
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