Volume 367 - XXIX International Symposium on Lepton Photon Interactions at High Energies (LeptonPhoton2019) - Parallel Sessions
Search for lepton-flavour violating and lepton-number violating decays of the $D^0$ meson and observation of $D^0\to K^-\pi^+e^+e^-$
F. Wilson*  on behalf of the BABAR collaboration
Full text: pdf
Pre-published on: October 15, 2019
Published on: December 17, 2019
Abstract
We report the observation of the rare charm decay $D^0\rightarrow K^-\pi^+e^+e^-$ and a search for nine lepton-number-violating (LNV) and three lepton-flavor-violating (LFV) neutral charm decays of the type $D^0\rightarrow h^{\prime-}h^{-}l^{\prime+}l^+$ and $D^0\rightarrow h^{\prime-}h^+ l^{\prime\pm}l^{\mp}$, where $h$ and $h^{\prime}$ represent a $K$ or $\pi$ meson and $l$ and $l^{\prime}$ an electron or muon. The analysis is based on $468$ fb$^{-1}$ of $e^+e^-$ annihilation data collected at or close to the $\Upsilon(4S)$ resonance with the BaBar detector at the SLAC National Accelerator Laboratory. We find the $D^0\rightarrow K^-\pi^+e^+e^-$ branching fraction in the invariant mass range $0.675< m(e^+e^-) < 0.875$ GeV/c$^{2}$ of the electron-positron pair to be $\mathcal{B}(D^0\rightarrow K^-\pi^+e^+e^-) = (4.0 \pm 0.5 \pm 0.2 \pm 0.1) \times 10^{-6}$, where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty in the branching fraction of the decay $D^0\rightarrow K^-\pi^+\pi^+\pi^-$ used as a normalization mode. In a set of regions of $m(e^+e^-)$ where long-distance effects are potentially small, we determine a 90\% confidence level (C.L.) upper limit on the branching fraction $\mathcal{B}(D^0\rightarrow K^-\pi^+\pi^+\pi^-) < 3.1\times 10^{-6}$. No significant signal is observed for any of the LFV and LNV modes, and we establish 90\% C.L. upper limits on the branching fractions in the range $(1.0 - 30.6)\times 10^{-7}$. The limits are between one and three orders of magnitude more stringent than previous measurements.
DOI: https://doi.org/10.22323/1.367.0073
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access