论文标题
首先观察$ e^+e^ - $ nihihitation $χ_{C1} $的直接生产
First Observation of the Direct Production of the $χ_{c1}$ in $e^+e^-$ Annihilation
论文作者
论文摘要
我们研究了$ j^{pc} = 1^{++} $ charmonium状态$χ_{c1}（1p）$在电子 - 峰值歼灭中，通过在$χ_{C1}（C1}（1p）$的质量上进行能量扫描。在BEPCII对撞机的BESIII检测器中收集数据。信号过程之间的干扰模式$ e^+e^ - \ toχ_{c1}（1p）\toγJJ/ψ\toγμ^+μ^ - $和背景过程$ e^+e^+e^ - \toγ_{ j/ψ\toγ_{\ rm {isr}}μ^+μ^ - $和$ e^+e^ - \toγ_{\ rm {isr {isr}}μ^+μ^ - $是通过组合所有数据样本观察到的。观察到$χ_{C1}（1p）$信号的意义为5.1 $σ$。这是直接以$ e^+e^ - $ nihihation产生的$ c $ - 至今状态的第一个观察。 $χ_{C1}（1p）$共振的电子宽度确定为$γ_{ee} =（0.12^{+0.13} _ { - 0.08}）
We study the direct production of the $J^{PC}=1^{++}$ charmonium state $χ_{c1}(1P)$ in electron-positron annihilation by carrying out an energy scan around the mass of the $χ_{c1}(1P)$. The data were collected with the BESIII detector at the BEPCII collider. An interference pattern between the signal process $e^+e^-\to χ_{c1}(1P) \to γJ/ψ\toγμ^+μ^-$ and the background processes $e^+e^-\to γ_{\mathrm{ISR}} J/ψ\toγ_{\rm{ISR}}μ^+μ^-$ and $e^+e^-\toγ_{\rm{ISR}}μ^+μ^-$ are observed by combining all the data samples. The $χ_{c1}(1P)$ signal is observed with a significance of 5.1$σ$. This is the first observation of a $C$-even state directly produced in $e^+e^-$ annihilation. The electronic width of the $χ_{c1}(1P)$ resonance is determined to be $Γ_{ee}=(0.12^{+0.13}_{-0.08})~\mathrm{eV}$, which is of the same order of magnitude as theoretical calculations.
