Implications of the evidence for direct $\mathbf{CP}$ violation in $D\to {\pi }^{+}{\pi }^{-}$ decays

Abstract

The observation of $CP$ violation in the difference of $CP$ asymmetries between $D\to K^{+}{K}^{-}$ and $D\to {\pi }^{+}{\pi }^{-}$ has raised a debate whether the observed asymmetries can be regarded as a signal of physics beyond the standard model (SM). In this paper we obtain all the topological amplitudes and isospin amplitudes directly from measured observables for $D\to \pi \pi$. These results unambiguously imply a very large penguin contribution, having a central value $4.74$ times the magnitude of the amplitude for $D^0\to {\pi }^{+}{\pi }^{-}$. This fitted central value differs from a reasonable SM estimate of $10\%$ with a significance greater than $3.3\sigma$. In contrast to previous studies, we present model-independent arguments based only on unitarity of re-scattering amplitudes to show that large penguins cannot arise from re-scattering alone and likely indicate physics beyond the SM. In a model-independent approach we show how a very small contribution from physics beyond the SM with a large weak phase alleviates the problem.

8 pages, 10 figures; Version to be published in Phys. Rev. D

References in corpus (12)

• Observation of $CP$ violation in charm decays
• New Physics and CP Violation in Singly Cabibbo Suppressed D Decays
• Direct CP asymmetry in $D\to {\pi }^{-}{\pi }^{+}$ and $D\to K^{-}{K}^{+}$ in QCD-based approach
• On $SU(3{)}_F$ Breaking through Final State Interactions and CP Asymmetries in $D\to PP$ Decays
• Measurement of the time-integrated $CP$ asymmetry in $D^0\to K^{-}{K}^{+}$ decays
• Final-state interactions in the CP asymmetries of charm-meson two-body decays
• A $U$-Spin Anomaly in Charm CP Violation
• Search for CP violation in D^0 -> pi^0 pi^0 decays
• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2023
• Enhanced charm CP asymmetries from final state interactions
• Two is better than one: The U-spin-CP anomaly in charm
• Measurement of the time-integrated $CP$ asymmetry in $D^0\to {\pi }^0{\pi }^0$ decays at Belle II

Cited by in corpus (1)

• Polarisation fractions in $B\to V_1{V}_2$: U-Spin constraints and new physics signatures