标题： 与重离子在LHC的 UPC 中$γγ\toγγ$散射相关的中子发射 显示英文标题

标题： Neutron emission associated with $γγ\toγγ$ scattering in UPC of heavy ions at the LHC

摘要： 我们计算了在铅核对铅核的 UPC 中，与光子-光子散射相关的不同中子类别的截面，即$0n 0n$、$0nXn+Xn0n$和$Xn Xn$，这些中子类别可能在零度量能器（ZDCs）中被测量。计算是针对 ATLAS 的运动学条件进行的。我们的中子类别计算结果与现有数据进行了对比，这些数据是关于 UPC 中$\rho^0$产生的。我们得到了绝对截面的良好一致性和分数截面的非常良好结果，这为对应于$\gamma \gamma \to \gamma \gamma$散射的二光子产生类似计算提供了信心。我们给出了不同中子类别的绝对截面和分数截面。我们还展示了不同碰撞参数、光子快度、横向动量、二光子不变质量以及光子快度差的分布。光子分布的形状取决于中子类别，我们在本文中对此进行了量化。使用 ATLAS 主探测器和 ATLAS ZDCs 来验证我们的预测将是有价值的。 显示英文摘要

摘要： We calculate cross sections for the production of different neutron classes $0n 0n$, $0nXn+Xn0n$ and $Xn Xn$, possible to measure in Zero Degree Calorimeters (ZDCs), associated with photon-photon scattering in UPC of lead on lead. The calculations are performed for the ATLAS kinematics. Our calculations for neutron classes are tested against existing data for $\rho^0$ production in UPC. We get a good agreement for absolute cross section as well as very good results for fractional cross section which gives confidence to the analogous calculation for diphoton production, corresponding to $\gamma \gamma \to \gamma \gamma$ scattering. We present both absolute as well as fractional cross sections for the different neutron classes. We also show different distributions in impact parameter, photon rapidity, transverse momentum, diphoton invariant mass and photon rapidity difference. The shapes of the photon distributions depend on the neutron classes which we quantify in this paper. It would be valuable to test our predictions using the ATLAS main detector and the ATLAS ZDCs.