论文标题
非弹性核子核子横截面中阴影的证据
Evidence of shadowing in inelastic nucleon-nucleon cross section
论文作者
论文摘要
Glauber建模在重型离子碰撞的中心性测量中起关键作用。 Glauber模型中的一个中心输入参数是非弹性核子核子横截面$σ_ {\ text {nn}}}^{\ text {inel}} $，几乎总是取自Proton-Proton的测量值。在LHC Energies处$σ_{\ text {nn}}^{\ text {inel}} $取决于小$ x $处的QCD动力学，而低相互作用量表则预期对较大的Nuclei而言，阴影/饱和现象预计会变得更重要。因此，$σ_ {\ text {nn}}^{\ text {inel}} $ e.g.在PB+PB中，碰撞可能低于质子蛋白碰撞中所见。在本演讲中，我们演示了如何使用最近的$ w^\ pm $和$ z $测量值作为“标准蜡烛”来提取$σ_{\ text {nn}}^{\ text {\ text {inel}} $在pb+pb碰撞中。 Our analysis -- built on the ATLAS data, state-of-the-art NNLO QCD calculations and nuclear PDFs -- indicate that at the LHC energies $σ_{\text{nn}}^{\text{inel}}$ in Pb+Pb collisions is suppressed relative to the proton-proton measurements by tens of percents.我们证明这与核PDF的期望一致。
The Glauber modeling plays a key role in centrality-dependent measurements of heavy-ion collisions. A central input parameter in Glauber models is the inelastic nucleon-nucleon cross section $σ_{\text{nn}}^{\text{inel}}$ which is nearly always taken from proton-proton measurements. At the LHC energies $σ_{\text{nn}}^{\text{inel}}$ depends on the QCD dynamics at small $x$ and low interaction scales where the shadowing/saturation phenomena are expected to become relatively more important for larger nuclei than for the proton. Thus, $σ_{\text{nn}}^{\text{inel}}$ e.g. in Pb+Pb collisions may well be lower than what is seen in proton-proton collisions. In this talk, we demonstrate how to use the recent $W^\pm$ and $Z$ measurements as a "standard candle" to extract $σ_{\text{nn}}^{\text{inel}}$ in Pb+Pb collisions. Our analysis -- built on the ATLAS data, state-of-the-art NNLO QCD calculations and nuclear PDFs -- indicate that at the LHC energies $σ_{\text{nn}}^{\text{inel}}$ in Pb+Pb collisions is suppressed relative to the proton-proton measurements by tens of percents. We demonstrate that this is in line with expectations from nuclear PDFs.
