"Table 36" of "Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions"

CERN-LHC. The yields of strange (${\rm K}^{0}_{S}$, $\Lambda$, $\bar{\Lambda}$) and multi-strange ($\Xi^{-}$, $\bar{\Xi}^{+}$, $\Omega^{-}$, $\bar{\Omega}^{+}$) hadrons are measured at midrapidity in proton-proton (pp) collisions at $\sqrt{s}$ = 7 TeV as a function of the charged-particle multiplicity density (${\rm d}N_{\rm ch}/{\rm d}\eta$).The production rate of strange particles increases faster than that of non-strange hadrons, leading to an enhancement of strange particles relative to pions, similar to that found in nucleus-nucleus collisions as well as in proton-nucleus collisions at the LHC. This is the first observation of an enhanced production of strange particles in high-multiplicity pp collisions. The magnitude of this strangeness enhancement increases with the event activity, quantified by ${\rm d}N_{\rm ch}/{\rm d}\eta$, and with hadron strangeness. It reaches almost a factor of two for the $\Omega$ at the highest multiplicity presented. No enhancement is observed for particles with no strange quark content, demonstrating that the observed effect is strangeness rather than mass related. The results are not reproduced by any of the Monte Carlo models commonly used at the LHC, suggesting that further developments are needed for a complete microscopic understanding of strangeness production and indicating the presence of a phenomenon novel in high-multiplicity pp collisions.欧洲核子研究中心大型强子对撞机（CERN-LHC）：本实验在质心系能量√s=7 TeV的质子-质子（pp）碰撞中，于快度中点区域测量了奇异强子（K⁰_S、Λ、Λ̄）与多奇异强子（Ξ⁻、Ξ̄⁺、Ω⁻、Ω̄⁺）的产额，并分析其随带电粒子多重数密度（dN_ch/dη）的变化关系。奇异粒子的产生速率增长快于非奇异强子，使得奇异粒子相对于π介子的产额出现增强，这一现象与大型强子对撞机（LHC）中核-核碰撞及质子-核碰撞的观测结果一致。这是高多重数质子-质子碰撞中奇异粒子产生增强效应的首次观测。该奇异增强的强度随由dN_ch/dη表征的事件活动度以及强子奇异数的增加而升高；在本次报道的最高多重数区间内，Ω重子的产额增强倍数接近2。对于不含奇异夸克的粒子，未观测到显著增强，这表明观测到的效应源于奇异数而非粒子质量。当前大型强子对撞机（LHC）常用的各类蒙特卡洛模型均无法复现本次实验结果，这意味着若要完整理解奇异粒子产生的微观机制，仍需进一步发展理论模型，同时也表明高多重数质子-质子碰撞中存在新奇的物理现象。