B_c Meson Production Around the Z^0 Peak at a High Luminosity e^+ e^- Collider
B_c Meson Production Around the Z^0 Peak at a High Luminosity e^+ e^- Collider
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DOI：
10.1103/physrevd.85.094015
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发表时间：
2011-12
影响因子：
5
通讯作者：
Zhi Yang;Xing-Gang Wu;Gu Chen;Qi-Li Liao;Jia-Wei Zhang
中科院分区：
文献类型：
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作者：
Zhi Yang;Xing-Gang Wu;Gu Chen;Qi-Li Liao;Jia-Wei Zhang
考虑到在$Z^0$ -玻色子共振周围的能量上建立一个计划光度高达${\cal L}\propto 10^{34}\sim 10^{36}cm^{-2}s^{-1}$（超级$Z$ -工厂）的$e^+ e^-$对撞机的可能性，我们在非相对论性QCD的框架内详细讨论了通过$e^{+}+e^{-}\rightarrow (c\bar{b})[n]+b+\bar{c}$产生$(c\bar{b})$ -夸克元的问题。为了尽可能地简化硬散射振幅，并推导出用于未来事件模拟的解析表达式，我们采用了“改进迹线技术”来进行计算，而不是传统的在平方振幅水平上直接处理硬散射振幅。用$m_c=1.50\pm0.30$ GeV和$m_b=4.90\pm0.40$ GeV来预测夸克质量引起的总横截面不确定性。如果所有更高的$(c\bar{b})$ -夸克态以100衰变为基态$B_c$ （$|(c\bar{b})_{\bf 1}[^1S_0]>$）% efficiency, we obtain $\sigma_{e^{+}+e^{-}\rightarrow B_{c}+b+\bar{c}} =5.190^{+6.222}_{-2.419}$ pb, which shows that about $10^5 \sim 10^7$ $B_c$ events per operation year can be accumulated in the super $Z$-factory. If taking the collider energy runs slightly off the $Z^0$-peak, i.e. $\sqrt{S}=(1.00\pm0.05) m_Z$, the total cross-section shall be lowered by about one-order from its peak value. Such a super $Z$-factory shall provide another useful platform to study the properties of $B_c$ meson, or even the properties of its excited $P$-wave states, in addition to its production at the hadronic colliders Tevatron and LHC.
Considering the possibility to build an $e^+ e^-$ collider at the energies around the $Z^0$-boson resonance with a planned luminosity so high as ${\cal L}\propto 10^{34}\sim 10^{36}cm^{-2}s^{-1}$ (super $Z$-factory), we make a detailed discussion on the $(c\bar{b})$-quarkonium production through $e^{+}+e^{-}\rightarrow (c\bar{b})[n]+b+\bar{c}$ within the framework of non-relativistic QCD. To simplify the hard-scattering amplitude as much as possible and to derive analytic expressions for the purpose of future events simulation, we adopt the "improved trace technology" to do our calculation, which deals with the hard scattering amplitude directly at the amplitude level other than the conventional way at the squared-amplitude level. Total cross-section uncertainties caused by the quark masses are predicted by taking $m_c=1.50\pm0.30$ GeV and $m_b=4.90\pm0.40$ GeV. If all higher $(c\bar{b})$-quarkonium states decay to the ground state $B_c$ ($|(c\bar{b})_{\bf 1}[^1S_0]>$) with 100% efficiency, we obtain $\sigma_{e^{+}+e^{-}\rightarrow B_{c}+b+\bar{c}} =5.190^{+6.222}_{-2.419}$ pb, which shows that about $10^5 \sim 10^7$ $B_c$ events per operation year can be accumulated in the super $Z$-factory. If taking the collider energy runs slightly off the $Z^0$-peak, i.e. $\sqrt{S}=(1.00\pm0.05) m_Z$, the total cross-section shall be lowered by about one-order from its peak value. Such a super $Z$-factory shall provide another useful platform to study the properties of $B_c$ meson, or even the properties of its excited $P$-wave states, in addition to its production at the hadronic colliders Tevatron and LHC.