论文标题
$ e^{+} e^{ - } \ toηϕ $的研究通过Belle的初始状态辐射
Study of $e^{+}e^{-}\toηϕ$ via Initial State Radiation at Belle
论文作者
论文摘要
使用$ 980〜fb^{ - 1} $在$υ（ns）（ns）（n = 1,2,3,4,5）$周围收集的数据（n = 1,2,3,4,5）$ ressoncants $ e^{+e^{+} e^{ - } { - } \ frofthesholdto $ 3.955〜 GEV}/C^{2} $通过初始状态辐射。从多参数拟合中假设$ ϕ（2170）$在$ ηϕ $最终状态下，根据BESIII的先前测量，$ ϕ（1680）$的共鸣参数确定为$ m_ {ϕ（1680）} =（1683 \ pm 7 \ pm 9）分别错误），$γ_{ϕ（1680）} =（149 \ pm 12 \ pm 13） b} [ϕ（1680）\ toηϕ] =（122 \ pm 6 \ pm 13）〜{\ rm ev} $，$（219 \ pm 15 \ pm 18） $ ϕ（1680）\ toηϕ $衰减的分支分数确定为约20％。此外，$ j/ψ\ toηϕ $的分支分数为$（7.1 \ pm 1.0 \ pm 0.5）\ times 10^{ - 4} $。但是，在此分析中，在$ ηϕ $最终状态中没有明显观察到$ ϕ（2170）$信号，以及相应的$γ^{e^{e^{+} e^{ - }}} _ {ϕ（2170）} \ cdot {\ cdot {\ cal b}（\ cal b}（\ cal b}（2170）$ 0. EV} $（两个拟合），或$ 18.6〜 {\ rm EV} $（剩余两个拟合），以90％的置信度。
Using $980~fb^{-1}$ of data collected on and around the $Υ(nS)(n=1,2,3,4,5)$ resonances with the Belle detector at the KEKB collider, we measure the cross section of $e^{+}e^{-}\to ηϕ$ from threshold to $3.95~{\rm GeV}/c^{2}$ via initial-state radiation. From a multi-parameter fit assuming $ϕ(2170)$ exists in the $ηϕ$ final state according to previous measurement by BESIII, the resonant parameters of $ϕ(1680)$ are determined to be $m_{ϕ(1680)} = (1683 \pm 7 \pm 9)~{\rm MeV}/c^{2}$ (statistical and systematic errors, respectively), $Γ_{ϕ(1680)} = (149 \pm 12 \pm 13)~{\rm MeV}$ and, depending on the possible presence of interfering resonances, $Γ^{e^{+}e^{-}}_{ϕ(1680)}\cdot {\cal B}[ϕ(1680)\toηϕ] = (122 \pm 6 \pm 13)~{\rm eV}$, $(219 \pm 15 \pm 18)~{\rm eV}$, $(163 \pm 11 \pm 13)~{\rm eV}$ or $(203 \pm 12 \pm 18)~{\rm eV}$. The branching fraction of $ϕ(1680)\toηϕ$ decay is determined to be approximately 20%. Additionally, the branching fraction for $J/ψ\toηϕ$ is measured to be $(7.1\pm 1.0 \pm 0.5)\times 10^{-4}$. However, there is no significant observed $ϕ(2170)$ signal in the $ηϕ$ final states in this analysis, and correspondingly the upper limit for $Γ^{e^{+}e^{-}}_{ϕ(2170)}\cdot {\cal B}(ϕ(2170)\toηϕ)$ is determined to be either $0.17~{\rm eV}$ (for two fits), or $18.6~{\rm eV}$ (remaining two fits), at 90% confidence level.
