Measurement of singly Cabibbo-suppressed decays D⁰ → π⁰π⁰π⁰, π⁰π⁰η, π⁰ηη and ηηη

Abstract

Using a data sample of $e^{+}{e}^{-}$ collision data corresponding to an integrated luminosity of 2.93 $\text{fb}{}^{-1}$ collected with the BESIII detector at a center-of-mass energy of $\sqrt{s}=3.773\text{GeV}$, we search for the singly Cabibbo-suppressed decays $D^0\to {\pi }^0{\pi }^0{\pi }^0$, ${\pi }^0{\pi }^0\eta$, ${\pi }^0\eta \eta$ and ηηη using the double tag method. The absolute branching fractions are measured to be $\mathcal{B}(D^0\to {\pi }^0{\pi }^0{\pi }^0)=(2.0\pm 0.4\pm 0.3)\times {10}^{-4}$, $\mathcal{B}(D^0\to {\pi }^0{\pi }^0\eta )=(3.8\pm 1.1\pm 0.7)\times {10}^{-4}$ and $\mathcal{B}(D^0\to {\pi }^0\eta \eta )=(7.3\pm 1.6\pm 1.5)\times {10}^{-4}$ with the statistical significances of 4.8σ, 3.8σ and 5.5σ, respectively, where the first uncertainties are statistical and the second ones systematic. No significant signal of $D^0\to \eta \eta \eta$ is found, and the upper limit on its decay branching fraction is set to be $\mathcal{B}(D^0\to \eta \eta \eta )<1.3\times {10}^{-4}$ at the 90% confidence level.