在TeV能区的超高能重离子碰撞中寻找并研究极端高温高密环境下普通核物质退禁闭为夸克胶子等离子体(QGP)物质形态的信号及其性质，是最近几十年来人们不懈为之探索的热门课题。由于光子不参与强相互作用，因此携带了碰撞初期硬散射的部分子信息，通过触发光子标记测量高能部分子喷注可以获取部分子的初态信息及其碎裂性质。本项目旨在利用LHC/ALICE实验数据，重建光子、带电粒子和高能强子喷注，利用光子标记喷注的黄金分析方法，研究光子及强子关联中的喷注结构和碎裂函数，检测不同部分子喷注在密度物质中的碎裂函数及强子化过程，测量不同色荷的部分子在QGP物质中的能量损失。通过完整喷注的重建，精确测量光子喷注和双喷注情形下的动量非对称性，研究喷注结构及喷注碎裂函数的核修正， 从而抽取密度物质特性参量，检验理论模型和格点QCD预言。

Studying the phases transition of nuclear matter and the properties of the Quark Gluon Plasma (QGP) in the ultra-relativistic high energy heavy ion collisions at TeV scale is most hot topic in recent decades. Hard probes (high pT or high mass), are exploited as “external” probes of the QGP to understand its interactions depending on the color charge and flavor of the probe. Compared to hadron probes, the high-energy direct photon is an unique probe since it produces at the early stage of collision and don't interact with medium strongly, therefore, photons remain unchanged while traversing the medium, set as the reference of the initial hard scattering, whereas the associated hadrons convey the information on the modifications experienced by the parton inside the medium. The objective of this proposal is to characterize the modifications of the jet structure and fragmentation function properties in heavy ion collisions by measuring the jets using photon tagged method in LHC/ALICE experiment. In particular, with properly identified direct photons, one can study the properties of hadrons originating from the fragmentation of a hard scattered quark accompanying the photon in a 2->2 hard process. Studying the jet fragmentation pattern and jet structure as a function of parton color charge (quark or gluon) can provide discriminative and crucial information on the parton-shower and energy loss mechanism that in turn will enable to characterize qualitatively and quantitatively the parton-medium interactions.