Speaker
Description
Flavor-changing neutral current (FCNC) processes are rare within the Standard Model (SM) as they cannot occur at tree level and are suppressed at loop level by the Glashow-Iliopoulos-Maiani (GIM) mechanism. In $D$-meson decays, the GIM cancellation is almost exact, leading to expected branching fractions for $c\to u l^- l^+$ processes of order $\mathcal{O}(10^{-9})$. However, long-distance effects can raise this to $\mathcal{O}(10^{-6})$. Recently, the LHCb collaboration reported a measurement of the $D^0\to K^-\pi^+\mu^+\mu^-$ branching fraction $\mathcal{B}(D^0\to K^-\pi^+\mu^+\mu^-) = (4.17\pm0.12\pm0.40)\times 10^{-6}$ in the mass range $0.675< m(\mu^+\mu^-) < 0.875$ GeV$/c^{2}$. The LHCb collaboration has also reported on hints for deviation from lepton universality in decays of the type $b\to s l^- l^+$.
In this talk, we report on a search for the FCNC decay $D^0\to K^-\pi^+e^+e^-$ using data taken by the BABAR experiment at the SLAC National Accelerator Laboratory.
