arXiv 1710.004362017-10-01nucl-ex

在相对论重离子对撞机上测量Au + Au碰撞中的超triton寿命

Measurement of hyper triton lifetime in Au + Au collisions at the Relativistic Heavy-Ion Collider

The STAR Collaboration

备注：: 7 pages, 4 figures, submit for publication
发表信息：: Phys. Rev. C 97, 054909 (2018)
DOI：: 10.1103/PhysRevC.97.054909

摘要：

提出了一种精确测量超曲子寿命的方法。在这封信中，介子衰变模式$\mathrm{{^3_Λ}H \rightarrow ^3He + π^-}$和$\mathrm{{^3_Λ}H \rightarrow d + p + π^-}$被用来重建超夸克从收集的金+金碰撞数据的STAR合作在RHIC。使用最小$χ^2$估计来确定$τ= 142^{+24}_{-21}\,{\rm (stat.)} {\pm} 31\,{\rm (syst.)}$ ps的寿命。该寿命比自由$Λ$的寿命$τ= 263\pm2$ ps短约50%，表明在超核系统中存在强的超子-核子相互作用。介子衰变通道的分支比也被确定为满足B.R. $_{(^3{\rm He}+π^-)}/$（B.R. $_{(^3{\rm He}+π^-)}+$ B.R. $_{(d+p+π^-)})$ = $0.32\rm{\pm}0.05\,{\rm (stat.)}\pm 0.08\,{\rm (syst.)}$。我们的比值结果支持赋值$J(\mathrm{^{3}_ΛH})$ = $\frac{1}{2}$而不是$J(\mathrm{^{3}_ΛH})$ = $\frac{3}{2}$。这些测量将有助于约束超子-重子相互作用模型。

英文摘要：

A precise measurement of the hypertriton lifetime is presented. In this letter, the mesonic decay modes $\mathrm{{^3_Λ}H \rightarrow ^3He + π^-}$ and $\mathrm{{^3_Λ}H \rightarrow d + p + π^-}$ are used to reconstruct the hypertriton from Au+Au collision data collected by the STAR collaboration at RHIC. A minimum $χ^2$ estimation is used to determine the lifetime of $τ= 142^{+24}_{-21}\,{\rm (stat.)} {\pm} 31\,{\rm (syst.)}$ ps. This lifetime is about 50\% shorter than the lifetime $τ= 263\pm2$ ps of a free $Λ$, indicating strong hyperon-nucleon interaction in the hypernucleus system. The branching ratios of the mesonic decay channels are also determined to satisfy B.R.$_{(^3{\rm He}+π^-)}/$(B.R.$_{(^3{\rm He}+π^-)}+$B.R.$_{(d+p+π^-)})$ = $0.32\rm{\pm}0.05\,{\rm (stat.)}\pm 0.08\,{\rm (syst.)}$. Our ratio result favors the assignment $J(\mathrm{^{3}_ΛH})$ = $\frac{1}{2}$ over $J(\mathrm{^{3}_ΛH})$ = $\frac{3}{2}$. These measurements will help to constrain models of hyperon-baryon interactions.

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英文摘要：

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