论文标题
部分可观测时空混沌系统的无模型预测
Underlying-event properties in pp and p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV
论文作者
论文摘要
我们报告有关在pp中使用爱丽丝在lhc和p $ - $ pb碰撞$ \ sqrt {s _ {\ rm nn}} = 5.02 $ tev的LHC和p $ - $ pb碰撞的基础事件的属性。事件活动通过带电的粒子编号量化，总结 - $ p _ {\ rm t} $密度，以领先粒子横向动量的函数（$ p _ {\ rm t}^{\ rm trig} $）测量。这些数量在相对于事件中的领先粒子的三个方位角区域中进行了研究：朝向，远距离和横向。在Mid-peudorapition（$ | | <0.8 $）处，针对三种不同的$ p _ {\ rm t} $阈值（0.15、0.5和1 GEV/$ C $）提出了结果。横向区域中对基础事件最敏感的事件活动在PP和P $ - $ - $ -PB碰撞中都表现出相似的行为，即，对于低$ P _ {\ rm t}^$ p _ {\ rm t}^$ rm trig a rm rm rm rm rm a rm p _ {\ rm t}^{\ rm t}^{\ rm trig} $ a t}^{\ rm trig} \大约5 $ gev/$ c $。将PP碰撞的结果与其他质量质量能量的现有测量结果进行了比较。在横向区域测量的贡献减法后，还分析了朝向和外星区域的数量。剩下的类似喷气的粒子密度在PP和P $ - $ - $ PB冲突中，对于$ p _ {\ rm t}^{\ rm trig}> 10 $ gev/$ c $，而对于较低的$ p _ {\ rm t}^{\ rm t}^{\ rm trig} $ coll pp $ coll p $ p $ p $ p p $ p p $ p $ p $ - 将测量结果与毕曲霉8和EPOS LHC Monte Carlo事件发生器的预测进行了比较。
We report about the properties of the underlying event measured with ALICE at the LHC in pp and p$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. The event activity, quantified by charged-particle number and summed-$p_{\rm T}$ densities, is measured as a function of the leading-particle transverse momentum ($p_{\rm T}^{\rm trig}$). These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different $p_{\rm T}$ thresholds (0.15, 0.5, and 1 GeV/$c$) at mid-pseudorapidity ($|η|<0.8$). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p$-$Pb collisions, namely, a steep increase with $p_{\rm T}^{\rm trig}$ for low $p_{\rm T}^{\rm trig}$, followed by a saturation at $p_{\rm T}^{\rm trig} \approx 5$ GeV/$c$. The results from pp collisions are compared with existing measurements at other centre-of-mass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contribution measured in the transverse region. The remaining jet-like particle densities are consistent in pp and p$-$Pb collisions for $p_{\rm T}^{\rm trig}>10$ GeV/$c$, whereas for lower $p_{\rm T}^{\rm trig}$ values the event activity is slightly higher in p$-$Pb than in pp collisions. The measurements are compared with predictions from the PYTHIA 8 and EPOS LHC Monte Carlo event generators.
