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

Abstract

We study the ${\rm Y}(1S)$ 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 ${\rm Y}(2S)$ and ${\rm Y}(3S)$ resonances. The ${\rm Y}(1S)$ resonance is reconstructed from the decay ${\rm Y}(nS)\to {\pi }^{+}{\pi }^{-}{\rm Y}(1S)$, $n=2,3$. We also study the processes $\gamma \gamma \to {\eta }_c\to {\eta }^{\prime }{K}^{+}{K}^{-}$, ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$, 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 ${\rm Y}(nS)$ ($n=2,3,4$) resonances. A Dalitz plot analysis is performed of ${\eta }_c$ decays to ${\eta }^{\prime }{K}^{+}{K}^{-}$, ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$, 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 ${\eta }^{\prime }$ final states in association with scalar mesons as they relate to the identification of the scalar glueball.

Presented at the "Eighth Workshop on Theory, Phenomenology and Experiments in Flavour Physics''-FPCapri2022; On behalf of the BaBar Collaboration