A consistent picture for large penguins in D → π +π -, K +K -

Joachim Brod, Yuval Grossman, Alexander L. Kagan, Jure Zupan

Research output: Contribution to journalArticlepeer-review

88 Scopus citations


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, ΔACP, 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 ΔACP, 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 ΔACP. Expectations for the individual CP asymmetries are also discussed.

Original languageEnglish
Article number161
JournalJournal of High Energy Physics
Issue number10
StatePublished - 2012
Externally publishedYes


  • CP violation
  • Standard model


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