CP Violation in Charm: a New Method

Abstract

We propose for the first time a method to perform analysis of time-dependent CP asymmetries in charm by using both, correlated and un-correlated $D^0$ mesons. Here we consider the decay channels $D^0\to K^+ K^-$ and $D^0\to \pi^+ \pi^-$. The channel $D^0\to K^+ K^-$ will be used to measure the mixing phase, and the difference between the measured phase $D^0\to K^+ K^-$ and $D^0\to \pi^+ \pi^-$ will open the door to the first measurement of $\beta_c$, one of the angle of the charm unitarity triangle. Since in the standard model CP asymmetries in charm are expected to be small, any observation of large time dependent asymmetries or mismatch between predicted and observed value for $ \beta_c$ could signify new physics. We perform and show results of numerical analysis made considering Super$B$ running at charm threshold, Super$B$ running at $\Upsilon(4S)$ and LHCb and find that Super$B$ and LHCb will be able to measure $\beta_{c,eff}$ with a precision of $1.3^\circ$ and $1.4^\circ$ respectively. The same analysis shows that $\phi_{MIX}$ could be measured at Super$B$ with a precision of $1.3^\circ$.