Observation of double $s\bar{s}$ production in $e^{+}{e}^{-}$ collision at $\sqrt{s}=3.08\text{GeV}$

Abstract

We report the observation of significant double-$s\bar{s}$ production in the $e^{+}{e}^{-}$ continuum, based on the measurement of prompt $\varphi$ mesons produced in association with hadrons containing an $s$ quark or an $s\bar{s}$ pair. In an analysis of $e^{+}{e}^{-}$ collision data collected by the BESIII experiment at $\sqrt{s}=3.08\text{GeV}$, the ratio $\sigma (e^{+}{e}^{-}\to \varphi s\bar{s}+\text{anything})/\sigma (e^{+}{e}^{-}\to \varphi +\text{anything})$ is determined to be $(40.4\pm 1.7_{stat.}\pm 1.5_{syst.})\%$ by detecting and measuring $e^{+}{e}^{-}\to \varphi +X(s\bar{s})$, where $X(s\bar{s})$ denotes an $\eta$ meson, an ${\eta }^{\prime }$ meson, or one of the strange-meson pairs $K^{+}{K}^{-}$, $K^{+}{K}^{\ast -}$, $K^{-}{K}^{\ast +}$, $K^0{\bar{K}}^0$, and $K^0{\bar{K}}^{\ast 0}+\text{c.c.}$. The level of double-$s\bar{s}$ production is in line with the double-$c\bar{c}$ production reported by the Belle and \babar\ collaborations, for which theoretical calculations predict lower rates. The experimental measurement of double $s\bar{s}$ production at BESIII can shed light on the understanding of quark hadronization and QCD.