Study ofJ/ψ→ηϕπ+π−at BESIII

Based on a sample of $2.25\times {10}^{8}J/\psi$ events taken with the BESIII detector at the BEPCII collider, we present the results of a study of the decay $J/\psi \to \eta \varphi {\pi }^{+}{\pi }^{-}$. The $Y(2175)$ resonance is observed in the invariant mass spectrum of $\varphi f_0(980)$ with a statistical significance of greater than $10\sigma$. The corresponding mass and width are determined to be $M=2200\pm 6(\mathrm{stat})\pm 5(\mathrm{syst})\mathrm{MeV}/c^2$ and $\mathrm{\Gamma }=104\pm 15(\mathrm{stat})\pm 15(\mathrm{syst})\mathrm{MeV}$, respectively, and the product branching fraction is measured to be $\mathcal{B}(J/\psi \to \eta Y(2175),Y(2175)\to \varphi f_0(980),f_0(980)\to {\pi }^{+}{\pi }^{-})=(1.20\pm 0.14(\mathrm{stat})\pm 0.37(\mathrm{syst}))\times {10}^{-4}$. The results are consistent within errors with those of previous experiments. We also measure the branching fraction of $J/\psi \to \varphi f_1(1285)$ with $f_1(1285)\to \eta {\pi }^{+}{\pi }^{-}$ and set upper limits on the branching fractions for $J/\psi \to \varphi \eta (1405)/\varphi X(1835)/\varphi X(1870)$ with $\eta (1405)/X(1835)/X(1870)\to \eta {\pi }^{+}{\pi }^{-}$ at the 90% confidence level.