TC2模型下荷电介子top(∏_t^+)衰变过程研究

The decay process of charged top-pion(∏_t^+) in topcolor assisted Technicolor(TC2) model

为了给高能实验探测top-pion介子提供有价值的理论指导,我们计算了∏+t介子的各衰变道(∏+t→t-b、∏+t→c-b、∏+t→W+γ、∏+t→W+Z0)的衰变分支比.结果表明:∏+t→t-b,∏+t→c-b应是探测∏+t介子的主要衰变道.由于∏+t→c-b道是味改变的,背景比较清晰,所以对于较轻的∏+t介子,它是探测∏+t介子的理想衰变道;而对于较重的∏+t介子,∏+t→t-b是最主要的衰变道,但由于∏+t→t-b衰变道的背景不是很清晰,并且重的∏+t介子的衰变宽度很大,使得通过该道探测重的∏+t介子比较困难.

Our study provides a valuable theoretical instruction for the probing of the charged top-pion. We calculate the decay branching ratio of charged top-pion （П^＋t） systematically, which can help us to search for charged top-pion. The results show that the main decay channels to probe П^＋t are the tree level modes： П^＋t→tb and П^＋t→cb. The background of the flavor-changing channelП^＋t→cb should be cleaner than that of theП^＋t→tb channel. ThusП^＋t→cb is the best channel to detect light П^＋t . For heavy П^＋t,П^＋t→tb is the dominent decay mode, we should detect charged top-pion via this channel, but the background of the П^＋t→tb channel is large. On the other hand, the total decay width is very large for heavy charged top-pion, sb, it is more difficult for us to detect heavyП^＋t.