Speaker
Rahul Sinha
(IMSc Chennai)
Description
The observation of CP violation in $D\to K^+K^-$ and $D\to \pi^+\pi^-$ has raised a debate whether the observed CP asymmetries can be regarded as a signal of physics beyond the standard model (SM). We show that the measured observables for $D\to \pi\pi$ unambiguously imply a very large penguin contribution that is greater than $5\%$ of the amplitude for $D^+\to\pi^+ \pi^0$ at a significance greater than $3.6 \sigma$. We present arguments based only on unitarity of re-scattering amplitudes to show that large penguin contribution cannot arise from re-scattering and indicate physics beyond the SM. In a model independent approach, we show how a very small contribution from physics beyond the SM with a weak phase alleviates the problem.
