摘要
LHCb实验利用质心系能量为13 TeV、积分亮度为5.4 fb^(-1)的质子-质子对撞数据测量了粲重子Ω_(c)^(0)和Ξ_(c)^(0)的寿命.该研究通过四体衰变末态pK^(-)K^(+)π^(+)重建出瞬发于质子-质子对撞顶点的粲重子Ω_(c)^(0)和Ξ_(c)^(0),测量得到Ω_(c)^(0)的寿命为276.5±13.4±4.4±0.7 fs,Ξ_(c)^(0)的寿命为148.0±2.3±2.2±0.2 fs,其中三项不确定度分别为统计不确定度、系统不确定度以及来自于D^(0)介子寿命的不确定度.本论文的测量结果和此前其他实验结果的世界平均值不相符,但与LHCb实验之前利用底强子半轻衰变过程的测量结果一致,从而确立了粲重子新的寿命排序.LHCb实验本次测量得到的Ω_(c)^(0)寿命大约是之前世界平均值的四倍,是世界上最精确的Ω_(c)^(0)寿命测量结果.
A measurement of the lifetimes of theΩ_(c)^(0)andΞ_(c)^(0)baryons is reported using proton-proton collision data at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.4 fb;collected by the LHCb experiment.TheΩ_(c)^(0)andΞ_(c)^(0)baryons are produced directly from proton interactions and reconstructed in the p K^(-)K^(+)π^(+)nal state.TheΩ_(c)^(0)lifetime is measured to be 276.5±13.4±4.4±0.7 fs,and theΞ_(c)^(0)lifetime is measured to be 148.0±2.3±2.2±0.2 fs,where the first uncertainty is statistical,the second systematic,and the third due to the uncertainty on the D^(0)lifetime.These results con firm previous LHCb measurements based on semileptonic beauty-hadron decays,which disagree with earlier results of a four times shorterΩ_(c)^(0)lifetime,and provide the single most precise measurement of theΩ_(c)^(0)lifetime.
