English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We investigate the maximum size of CP violating effects in $D$-mixing withinthe Standard Model (SM), using Heavy Quark Expansion (HQE) as theoreticalworking tool. For this purpose we determine the leading HQE contributions andalso $\alpha_s$ corrections as well as subleading $1/m_c$ corrections to theabsorptive part of the mixing amplitude of neutral $D$ mesons. It turns outthat these contributions to $\Gamma_{12}$ do not vanish in the exactSU$(3)_\mathrm{F}$ limit. Moreover, while the leading HQE terms give a resultfor $\Gamma_{12}$ orders of magnitude lower than the current experimentalvalue, we do find a sizeable phase. In the literature it was suggested thathigher order terms in the HQE might be much less affected by the severe GIMcancellations of the leading terms; it is even not excluded that these higherorder terms can reproduce the experimental value of $y$. If such an enhancementis realized in nature, the phase discovered in the leading HQE terms can have asizeable effect. Therefore, we think that statements like: {\it "CP violatingeffects in $D$-mixing of the order of $10^{-3}$ to $10^{-2}$ are an unambigoussign of new physics"}--given our limited knowlegde of the SM prediction--arepremature. Finally, we give an example of a new physics model that can enhancethe leading HQE terms to $\Gamma_{12}$ by one to two orders of magnitude.

How large can the SM contribution to CP violation in $D^0-\bar D^0$ mixing be?