论文标题
$λπ^+$和$λπ^ - $ \ bar {k} n(i = 1)$质量阈值$λ_c^+\rightArrowλπ^+π^+π^ - $ decay的首次观察。
First Observation of $Λπ^+$ and $Λπ^-$ Signals near the $\bar{K}N (I=1)$ Mass Threshold in $Λ_c^+\rightarrowΛπ^+π^+π^-$ Decay
论文作者
论文摘要
使用980 Fb $^{ - 1} $的数据样本,在Kekb不对称能量$ E^+E^ - $ collider中收集的Belle检测器,我们介绍了对$λπ^+$和$ unvariant质量分布的调查结果,以寻找在decay $λ_c^+ured的质量分布。我们在每个质量分配中发现一个明显的信号。当将其解释为共振时,我们可以找到$λπ^+$($λπ^ - $)组合的组合,质量为$ 1434.3 \ pm 0.6(\ mathrm {stat})\ pm 0.9(\ mathrm {syst}} 2.5(\ Mathrm {syst})$ MEV/$ C^2 $],固有宽度$ 11.5 \ pm 2.8(\ Mathrm {stat})\ pm 5.3(\ Mathrm {syst}} 23.6(\ Mathrm {syst})$ MEV/$ C^2 $],其意义为7.5 $σ$(6.2 $σ$)。由于这两个信号非常接近$ \ bar {k} n $阈值,因此我们还研究了$ \ bar {k} n $ cusp的可能性,发现\我们无法区分由于数据示例的大小有限,因此我们无法区分这两个解释。
Using the data sample of 980 fb$^{-1}$ collected with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we present the results of an investigation of the $Λπ^+$ and $Λπ^-$ invariant mass distributions looking for substructure in the decay $Λ_c^+\rightarrowΛπ^+π^+π^-$. We find a significant signal in each mass dis\ tribution. When interpreted as resonances, we find for the $Λπ^+$ ($Λπ^-$) combination a mass of $1434.3 \pm 0.6 (\mathrm{stat}) \pm 0.9(\mathrm{syst})$ MeV/$c^2$ [$1438.5 \pm 0.9 (\mathrm{stat}) \pm 2.5(\mathrm{syst})$ MeV/$c^2$], an intrinsic width of $11.5 \pm 2.8 (\mathrm{stat}) \pm 5.3(\mathrm{syst})$ MeV/$c^2$ [$33.0 \pm 7.5 (\mathrm{stat}) \pm 23.6(\mathrm{syst})$ MeV/$c^2$] with a significance of 7.5$σ$ (6.2$σ$). As these two signals are very close to the $\bar{K}N$ threshold, we also investigate the possibility of a $\bar{K}N$ cusp, and find that \ we cannot discriminate between these two interpretations due to the limited size of the data sample.