Abstract
A long-standing puzzle in charm physics is the large difference between the D 0 → K + K − and D 0 → π + π − decay rates. Recently, the LHCb and CDF collaborations reported a surprisingly large difference between the direct CP asymmetries, ΔA CP, in these two modes. We show that the two puzzles are naturally related in the Standard Model via s- and d-quark “penguin contractions”. Their sum gives rise to ΔA CP, while their difference contributes to the two branching ratios with opposite sign. Assuming nominal SU(3) breaking, we perform a U-spin based fit to the D 0 → K + π −, π + K − , π + π − , K + K − decay rates, which yields large penguin contractions that naturally explain ΔA CP. Expectations for the individual CP asymmetries are also discussed.
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Brod, J., Grossman, Y., Kagan, A.L. et al. A consistent picture for large penguins in D →π + π −, K + K − . J. High Energ. Phys. 2012, 161 (2012). https://doi.org/10.1007/JHEP10(2012)161
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DOI: https://doi.org/10.1007/JHEP10(2012)161