强子化是强相互作用理论的基本问题，也是相对论重离子碰撞中夸克胶子等离子体（QGP）与末态可观测量联系的关键。RHIC 物理研究表明：夸克组合是QGP 强子化的必要机制。最近STAR 的 Beam Energy Scan 实验和CERN 的SPS 实验在5-20GeV 能区发现了强子产生的新特征，如强子椭圆流的组分夸克数目标度性在11.5GeV被破坏。此能区夸克组合机制是否仍然适用? QGP新物质态是否产生？本项目将利用山东夸克组合模型对RHIC和SPS能区重离子碰撞中热强子的产生规律进行系统研究。通过对强子产额、动量谱、集体流、重子-反重子关联和涨落等性质的研究，检验夸克组合机制的普适性，深入理解强子化规律，探索较低SPS能区QGP的产生阈以及相变特征。

Hadronization is one of open questions in quantum chromodynamics (QCD) in the non-perturbative regime. In relativistic heavy ion collisions, it is a key bridge between final-state observables and the quark gluon plasma (QGP) produced in early stage of collisions. RHIC physics show that the quark combination mechanism plays an important role in the hadronization of QGP. Recently, the Beam Energy Scan program of STAR Collaboration and SPS experiments at CERN found new features of hadron production in heavy ion collisions in the 5-20 GeV regions. For example, the quark number scaling for hadronic elliptic flow v2 is broken partially as the collision energy decreases to 11.5 GeV. Is the quark combination mechanism applicable in this energy region? Is QGP created? In this project, we will apply a quark combination model developed by Shandong Group to systematically study the production of thermal hadrons in a broad collisional energy region 5-200 GeV (from SPSto RHIC). We shall investigate yields and momentum distributions of various thermal hadrons, collective flows, baryon-antibaryon correlation and fluctuation to test the universality of quark combination mechanism and explore the threshold of QGP creation and the phase transition at lower SPS energies.