The emergence of the ΔU = 0 rule in charm physics

Yuval Grossman, Stefan Schacht

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49 Scopus citations


We discuss the implications of the recent discovery of CP violation in two-body SCS D decays by LHCb. We show that the result can be explained within the SM without the need for any large SU(3) breaking effects. It further enables the determination of the imaginary part of the ratio of the ΔU = 0 over ΔU = 1 matrix elements in charm decays, which we find to be (0.65 ± 0.12). Within the standard model, the result proves the non-perturbative nature of the penguin contraction of tree operators in charm decays, similar to the known non-perturbative enhancement of ΔI = 1/2 over ΔI = 3/2 matrix elements in kaon decays, that is, the ΔI = 1/2 rule. As a guideline for future measurements, we show how to completely solve the most general parametrization of the D → P+P system.

Original languageEnglish
Article number20
JournalJournal of High Energy Physics
Issue number7
StatePublished - 1 Jul 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019, The Author(s).


This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

FundersFunder number
Creative Commons Attribution License
National Science Foundation
Directorate for Mathematical and Physical Sciences1316222


    • CP violation
    • Heavy Quark Physics


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