Light meson spectroscopy and gluonium searches in ${\eta }_c$ and $\mathrm{{\rm Y}}(1S)$ decays at BaBar

We study the $\mathrm{{\rm Y}}(1S)$ radiative decays to $\gamma {\pi }^{+}{\pi }^{-}$ and $\gamma K^{+}{K}^{-}$ using data recorded with the BaBar detector operating at the SLAC PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider at center-of-mass energies at the $\mathrm{{\rm Y}}(2S)$ and $\mathrm{{\rm Y}}(3S)$ resonances. The $\mathrm{{\rm Y}}(1S)$ resonance is reconstructed from the decay $\mathrm{{\rm Y}}(nS)\to {\pi }^{+}{\pi }^{-}\mathrm{{\rm Y}}(1S)$, $n=2,3$. We also study the processes $\gamma \gamma \to {\eta }_c\to {\eta }^{\mathrm{\prime }}{K}^{+}{K}^{-}$, ${\eta }^{\mathrm{\prime }}{\pi }^{+}{\pi }^{-}$, and $\eta {\pi }^{+}{\pi }^{-}$ using a data sample of 519 $f{b}^{-1}$ recorded with the BaBar detector at center-of-mass energies at and near the $\mathrm{{\rm Y}}(nS)$ ($n=2,3,4$) resonances. A Dalitz plot analysis is performed of ${\eta }_c$ decays to ${\eta }^{\mathrm{\prime }}{K}^{+}{K}^{-}$, ${\eta }^{\mathrm{\prime }}{\pi }^{+}{\pi }^{-}$, and $\eta {\pi }^{+}{\pi }^{-}$. A new $a_0(1700)$ resonance is observed in the $\eta {\pi }^{\pm }$ invariant-mass spectrum from the ${\eta }_c\to \eta {\pi }^{+}{\pi }^{-}$ decay. We compare ${\eta }_c$ decays to $\eta$ and ${\eta }^{\mathrm{\prime }}$ final states in association with scalar mesons as they relate to the identification of the scalar glueball.