University of Colorado, Boulder, Colorado 80309, USA.
Phys Rev Lett. 2013 Nov 15;111(20):202301. doi: 10.1103/PhysRevLett.111.202301. Epub 2013 Nov 12.
We present results for three charmonia states (ψ', χc, and J/ψ) in d+Au collisions at |y|<0.35 and sqrt[s(NN)]=200 GeV. We find that the modification of the ψ' yield relative to that of the J/ψ scales approximately with charged particle multiplicity at midrapidity across p+A, d+Au, and A+A results from the Super Proton Synchrotron and the Relativistic Heavy Ion Collider. In large-impact-parameter collisions we observe a similar suppression for the ψ' and J/ψ, while in small-impact-parameter collisions the more weakly bound ψ' is more strongly suppressed. Owing to the short time spent traversing the Au nucleus, the larger ψ' suppression in central events is not explained by an increase of the nuclear absorption owing to meson formation time effects.
我们呈现了在 |y|<0.35 和 sqrt[s(NN)]=200 GeV 条件下，d+Au 碰撞中三个粲介子态（ψ'，χc 和 J/ψ）的结果。我们发现，相对于 J/ψ 的产额，ψ'的产额的修正在 midrapidity 附近与带电粒子多重数大致按比例变化，这一结果跨越了来自超级质子同步加速器和相对论重离子对撞机的 p+A、d+Au 和 A+A 结果。在大碰撞参数的碰撞中，我们观察到 ψ'和 J/ψ 的类似抑制，而在小碰撞参数的碰撞中，较弱束缚的 ψ'受到更强的抑制。由于 ψ'在穿过 Au 核时花费的时间较短，因此中央事件中 ψ'的更大抑制不能用由于介子形成时间效应导致的核吸收增加来解释。
