e^+e^-对撞机上Ξ_(bb)产生的研究

Investigation of Ξ_(bb) Production at e^+e^- collider

目前,对双重重子Ξcc的研究非常广泛。但对双重重子Ξbb产生的研究比较少。研究了e+e-湮灭过程中Ξbb的单举产生过程。Ξbb的产生可以因子化为两步:重夸克对bb的产生可以用微扰QCD理论处理;然后bb转化为重子Ξbb的过程只能在非相对论QCD的框架下进行。重夸克对bb可以处于两个态:自旋3S1的色三重态;自旋1S0的色六重态。详细研究了bb处这于两个态时转化为重子Ξbb的概率。结果发现:bb处于色三重态和色六重态时对Ξbb产生的贡献处于同一数量级上,这与对Ξcc产生研究的结果基本一致。同时,考虑了Z0共振态附近Ξbb的产生,发现Ξbb的产生率在Z0共振态时有很大的提高。这样的结果可以帮助在将来的高亮度的e+e-对撞机上找到Ξbb产生的信号。

At present, the doubly heavy baryons IIIcc have been widely studied. However, there is little detail investigation concerning the doubly heavy baryon IIIbb. In this paper, the inclusive production of IIIbb, in e^＋ e^- annihilation has been studied. One can use factorization for IIIbb production. The production of two heavy- quark pairs bb can be handled within perturbative QCD framework, then the transformation into the baryon IIIbb can be considered in the framework of non-relativistic QCD （NRQCD）. Heavy-quark pairs bb can combine in- to two states, i. e. , the spin state 3S1 with color triplet and ^1S0 with color sextet. Both the diquark bb in color sextet and triplet have been discussed. The results show that the contributions from these two color states play the equally important role, which is consistent with the studies on IIIcc production. At the Z0 resonance, a sig- nificant enhancement can be found in the IIIbb production. These results may help to find the signal of IIIbb at e^＋ e^- collider.