Abstract
We present the first QCD-based calculation of hadronic matrix elements with penguin topology determining direct CP-violating asymmetries in D0→π−π+ and D0→K−K+ nonleptonic decays. The method is based on the QCD light-cone sum rules and does not rely on any model-inspired amplitude decomposition, instead leaning heavily on quark–hadron duality. We provide a Standard Model estimate of the direct CP-violating asymmetries in both pion and kaon modes and their difference and comment on further improvements of the presented computation.
Highlights
Despite years of intense experimental efforts, CP-violation has never been unambiguously observed in the decays of up-type quarks
In order to estimate the size of the computed hadronic matrix elements we need to provide numerical inputs for various parameters used in this calculation
We use the value of fD = 201 ± 13 MeV for the D-meson decay constant obtained from the 2-point QCD sum rule analysis in [24], and the values fπ = 130.5 MeV and fK = 155.6 MeV respectively [6] for the pion and kaon decay constants
Summary
Despite years of intense experimental efforts, CP-violation has never been unambiguously observed in the decays of up-type quarks. In the Standard Model (SM) this fact can be explained by the suppression of all CP-violating amplitudes resulting from the smallness of relevant Cabbibo-Kobayashi-Maskawa (CKM) matrix elements. Accurate predictions of up-type CP-violating observables are hard to obtain, since the necessary hadronic matrix elements are dominated by long-distance contributions. In order to calculate these matrix elements one needs to employ a QCD-based method that deals with nonperturbative effects in a model-independent manner. CP-violating observables in exclusive singly Cabibbo-suppressed (SCS) decays of D-mesons using a variant of light-cone QCD sum rules (LCSRs). Observables that are sensitive to CP -violation are most often written in terms of asymmetries [1], aCP(f )
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