LHC能区强子-(多)奇异粒子关联及夸克物质性质的实验研究

With the principal aims of understanding the properties of quark-gluon plasma, ALICE has achieved a great many important results. In this proposal,we will measure the hadron-(multi)strange correlations in pp, p-Pb and Pb-Pb collisions with the aims of understanding the contributions of soft and hard processes to the (multi-)strange particle productions. By such a measurement, it is expected to understand both the enhancement of (multi-)strange production yields in nucleus-nucleus collisions compared to those in pp collisions and the suppression of (multi-)strange particle production at high transverse momentum (pt) and to shed light on possible new hadronization mechanisms, such as parton fragmentation outside the hot-dense medium, or recombination of partons from either partonic shower or thermal source. We will study the (multi-)strange baryon to K0S ratios as a function of transverse momentum at different multiplicity or centrality bins in pp, p-Pb and Pb-Pb collisions to search for the possible mechanisms, contributing to the anomalous enhancement of baryon production at intermediate transverse momentum observed in nucleus-nucleus interactions at RHIC and LHC. We will measure the (multi-)strange particle yields correlated to high pt triggered charged hadrons and study the away-side to near-side yield ratio to investigate the parton energy loss mechanism and to provide important information for the transport coefficient of jets in QGP medium. We will measure the anisotropic triangular flow of (multi-)strange particles in Pb-Pb and possibly also in p-Pb collisions to figure out that, to what extend, the so-called constituent quark number scaling observed at RHIC energies holds at TeV energies. It is expected that, by such a study, one can estimate the relative contributions to the anisotropic flow from partonic and hadronic phases as it is argued that multi-strange particles have small hadronic cross-sections and therefore are expected to be more sensitive to the quark-gluon-plasma phase than the hadronic one. The results at low transverse momentum (<3 GeV/c) will be compared to viscous hydrodynamical model calculations with or without hadronic rescattering afterburner to learn the quark matter properties such as sound velocity, shear viscosity and etc.. The results at higher transverse momentum (3-8 GeV/c) will be compared to jet quenching model calculations to gain information on path length dependence of parton energy loss.

以研究夸克胶子等离子体性质(QGP)为目标，大型重离子碰撞实验（ALICE）自运行以来已取得了一系列重要研究成果。本项目将利用ALICE实验数据，分析质子-质子、质子-铅和铅-铅碰撞产生的强子-（多）奇异粒子关联分布，测量源于硬、软过程或热密介质的（多）奇异粒子产额，探寻(多)奇异粒子产生的新机制和奇异粒子产额增加的根源；测量软、硬过程中(多)奇异重子介子产额比，探寻相对论重离子碰撞中中等横动量重子介子比反常增强的根源，探寻强子化新机制；测量伴随高能强子（喷注）产生的（多）奇异粒子的产额，测量背离端与近端（多）奇异粒子产额比，研究该产额比对奇异组分夸克数目的依赖行为，为揭示硬部分子与热密夸克物质相互作用时的能量损失机制和提取喷注在 QGP中的输运参数等提供重要信息；测量铅-铅碰撞中（多）奇异粒子的三角流，检验各向异性流的组分夸克数目标度性，为揭示QGP的性质和演化规律提供重要信息。

项目旨在通过分析喷注-（多）奇异粒子关联产额，研究重子介子比；分析（多）奇异粒子产额的多重数依赖行为，揭示奇异粒子产额增强的根源；研究（多）奇异粒子的各向异性集体运动行为，探索强子各向异性流的形成机制。项目完成了2.76 TeV和5.02 TeV铅-铅碰撞中奇异粒子和多奇异粒子的椭圆流和三角流的分析工作;合作指导完成了中性pi介子-强子关联的分析工作，测量了与高横动量中性pi介子关联的强子产额的核修正因子;指导分析了7 TeV和13 TeV质子-质子碰撞中（多）奇异粒子在喷注中的横动量分布，奇异重子介子比和多奇异重子与Lambda重子的比的横动量分布;联合指导完成了2.76 TeV质子-质子碰撞中中性pi介子和eta介子横动量谱的分析工作；分析质子-质子碰撞中奇异粒子产生的多重粒子数的依赖，发现奇异粒子产额随带电粒子多重数的增大而增大。发表ALICE合作组实验论文5篇，其中一篇发表在Nature Physics上。此外，为了揭示实验结果所蕴藏的物理机制，我们开展了一系列的唯象模型研究，发表唯象理论文章11篇。