AI 中文总结
该研究利用PYTHIA 8 Angantyr分析√s_NN=200 GeV的d+Au碰撞，探究硬-软关联，发现光子与π介子标记事例的活性类分布差异，分离出几何与残余关联贡献，为小核碰撞的相关研究提供了参考。
AI 中文摘要
小核碰撞系统中的事例活性选择将碰撞几何与硬散射伴随的软响应关联起来。我们采用PYTHIA 8.316 Angantyr，利用直接光子、衰变前的末态中性π介子以及anti-kT喷注，研究了质心系核子-核子碰撞能量√s_NN=200 GeV的d+Au碰撞中的这种关联。硬偏置因子用于比较硬事例进入某一活性类别的概率与经N^ND_coll加权的最小偏置参考值的差异。该模型预测，对于光子和π介子，最活跃类别的事例数减少，而外围类别的事例数增加。与π介子标记或包含式HardQCD事例相比，光子标记事例还具有更小的平均碰撞参数和更多的非衍射亚碰撞。通过将完全关联的Angantyr事例与经N_coll重加权的最小偏置参考值及因子化诊断方法进行比较，可将明确的几何贡献与残余的硬-软关联分离开来。类STAR和类PHENIX的粒子水平活性代理保持了类别排序，但给出了不同的类别概率。该计算为发生器水平的，未确定残余关联的唯一微观起源。
英文摘要
Event-activity selections in small nuclear collision systems couple collision geometry to the soft response accompanying a hard scattering. We examine this coupling in d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV with PYTHIA 8.316 Angantyr, using direct photons, terminal pre-decay neutral pions, and anti-kT jets. A hard-bias factor compares the probability for a hard event to enter an activity class with an $N^{ND}_{coll}$ -weighted minimum-bias reference. The model predicts a depleted most-active class and an enhanced peripheral class for both photons and pions. Photon-tagged events also sample a smaller mean impact parameter and more nondiffractive subcollisions than pion-tagged or inclusive HardQCD events. Comparing fully correlated Angantyr events with an Ncoll-reweighted minimum-bias reference and a factorized diagnostic separates the explicit geometric contribution from residual hard-soft correlations. STAR-like and PHENIX-like particle-level activity proxies preserve the class ordering but give different class probabilities. The calculation is generator-level and does not identify a unique microscopic origin for the residual correlations.
Comments7 pages, 9 figures
