论文标题
UPC：$ {\ mathrm j}/ψ$光增生性分析的强大工具
UPC: a powerful tool for ${\mathrm J}/ψ$ photoproduction analysis in ALICE
论文作者
论文摘要
当相互作用的核或质子的影响参数大于其半径之和时，就会发生超外外碰撞（UPC）。它们是由虚拟光子交换介导的。重载体介子的光生源特别有趣，因为它们将它们搭配到光子。爱丽丝合作在$ \ sqrt {s _ {\ rm nn}} = 5.02 $ tev的质量中心能量中分析了P-PB和PB-PB UPC，分别对应于$γ$ P和$γ$ -PB交互。该海报报告了$ {\ mathrm j}/ψ$ OFF质子和PB目标的独家光生启动，这分别阐明了饱和和核阴影的发生。更详细地，P-PB的结果衡量了Bjorken- $ x $从〜$ 10^{ - 2} $到〜$ 10^{ - 5} $的横截面的增长，而PB-PB的结果表明，核能在高能和低尺度的$ cou {\ Mathm j}的质量列出的核能和低标度质量范围内。
Ultra-peripheral collisions (UPC) occur when the interacting nuclei or protons have an impact parameter larger than the sum of their radii. They are mediated by virtual photon exchange. The photoproduction of heavy vector mesons is especially interesting because they couple to the photon. The ALICE Collaboration has analysed both p-Pb and Pb-Pb UPC at the centre-of-mass energy of $\sqrt{s_{\rm NN}} = 5.02$TeV which correspond to $γ$p and $γ$-Pb interactions, respectively. This poster reports the exclusive photoproduction of ${\mathrm J}/ψ$ off proton and Pb targets, which shed light on the occurrence of saturation and nuclear shadowing, respectively. In more detail, the p-Pb results measure the growth of the cross section for exclusive production over a wide range in Bjorken-$x$ from ~$10^{-2}$ to ~$10^{-5}$, while Pb-Pb results demonstrate the presence of nuclear shadowing at high energies and low scales of the order of the mass of the ${\mathrm J}/ψ$.
