Universal anti-baryon density in $e^+e^-$,$\gamma p$, pp, pA and AA collisions
Universal anti-baryon density in $e^+e^-$,$\gamma p$, pp, pA and AA collisions
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发表时间：
2006-10
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通讯作者：
Haidong Liu;Zhangbu Xu University of Science;T. China;Brookhaven National Laboratory;L. B. N. Laboratory
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作者：
Haidong Liu;Zhangbu Xu University of Science;T. China;Brookhaven National Laboratory;L. B. N. Laboratory
我们编制了超相对论重离子碰撞以及$pp$、$p\bar{p}$、$\gamma p$和$e^{+}e^{-}$中不同束流能量下反核产生的系统测量数据。从$A+A$、$p+A$、$pp(\bar{p})$和$\gamma p$对撞中$\bar{d}/\bar{p}$比推导出的反重子相空间密度，作为束流能量质心的函数，遵循一个普遍的分布，可以用统计模型来描述。结果表明，当碰撞以$g+g$或$\bar{q}+g$过程为主时，所有碰撞的反重子密度最高。在$e^+e^-$ LEP碰撞中，$q\bar{q}g$的横截面被一个相对于$q\bar{q}$的强耦合常数$\alpha_s$抑制。这可以一致地解释ALEPH相对于ARGUS在$e^+e^-\to ggg$中观察到的$\bar{d}$抑制。讨论了射流淬灭时重子在高横动量下的重子增强问题。
We compiled the systematical measurements of anti-nucleus production in ultra-relativistic heavy ion collisions as well as those in $pp$, $p\bar{p}$, $\gamma p$ and $e^{+}e^{-}$ at various beam energies. The anti-baryon phase space density inferred from $\bar{d}/\bar{p}$ ratio in $A+A$, $p+A$, $pp(\bar{p})$ and $\gamma p$ collisions is found to follow a universal distribution as a function of center of mass of beam energy and can be described in a statistical model. We demonstrated that anti-baryon density in all the collisions is the highest when the collisions are dominated by the processes of $g+g$ or $\bar{q}+g$. In $e^+e^-$ collisions at LEP, the cross section of $q\bar{q}g$ is suppressed by a factor of strong coupling constant $\alpha_s$ relative to $q\bar{q}$. This can consistently explain the $\bar{d}$ suppression observed by ALEPH relative to that in $e^+e^-\to ggg$ by ARGUS. We discuss the implications to the baryon enhancement at high transverse momentum at RHIC when jet is quenched.