Production of meson, baryon and light nuclei (A=2,3): investigating freeze-out dynamics and roles of energetic quarks and gluons in Au+Au collisions at RHIC
Production of meson, baryon and light nuclei (A=2,3): investigating freeze-out dynamics and roles of energetic quarks and gluons in Au+Au collisions at RHIC
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发表时间：
2013-02
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通讯作者：
Haidong Liu
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作者：
Haidong Liu
Production of meson, baryon and light nuclei (A=2, 3): investigating freeze-out dynamics and roles of energetic quarks and gluons in Au+Au collisions at RHIC Haidong Liu University of Science and Technology of China 2007 In relativistic heavy-ion collisions, a high temperature matter with strong interactions is produced. The Lattice QCD calculations predict a phase transition from hadronic matter to a quark-gluon plasma state, where the quarks are believed to be deconfined. In this thesis, we report the recent STAR measurements on identified hadron and light nuclei production in Au+Au 200 GeV collisions at RHIC. Light nuclei, which have small binding energies among the constituent nucleons, are believed to be formed at the moment of the thermal freeze-out. Therefore, the production of light nuclei provides a tool to measure the freeze-out properties. Benefitting from the high statistic data sample taken in RHIC Run IV, we have measured the He(3He) pT spectra and v2 at intermediate pT region (2 20 GeV when we compare our results to the low energy results. The d + d̄ v2 is found to follow the atomic mass number (A) scaling within errors and we observe a deviation of He + 3He v2 from the A scaling. The first negative v2 at RHIC has been observed for low pT d̄ in mid-central collisions. This is consistent with a large radial flow scenario. We have systematically studied the anti-baryon phase space density inferred from d̄/p̄ measurements in various collision systems at various energies. It is found that the anti-baryon density at the final-state coalescence saturates when the process from different collisions involving gluons. We use the particle identification capability of the STAR TPC and TOF detectors to measure the π± and p(p̄) spectra in large transverse momentum range (0.3 时, 氘核的 freeze-out体积不随对撞能量的变化而改变。通过对中横动量轻核椭圆流的 测量,我们发现氘核与反氘核的 v2在误差范围内服从组分核子数(A)的标度不变 性;而氦核与反氦核的 v2却在一定程度上偏离核子数的标度不变性。我们还测量 了低横动量的反氘核的 v2,这是 RHIC上观测到的第一个负值椭圆流。通过对 Blast-wave模型的比较和研究,我们发现重粒子(氘)的负值椭圆流与大径向流图 像相吻合。另外,通过对不同对撞系统(AA, pA, pp, p γ , − e e )和不同对撞能量中 反氘核和反质子的产额比( p d / )的研究,我们发现在各种反应机制中,胶子的 参与是(反)重子产生的重要条件。 在本文中,我们还将给出利用MRPC-TOF时间飞行谱仪探测器(样机)的 π、p数据和时间投影室中获得的带电粒子的电离能量损失(dE/dx)的数据,发展了 一种可以鉴别高动量区间的π介子和质子的新技术,将 STAR的π,p的粒子鉴定横 动量区间扩展到 12GeV/c。通过测量带电强子( p p, , ± π )的横动量谱 ( c GeV pT / 12 3 . 0 < < )。我们观察到在中横动量区间有相关重子产额加强的现 象,这可以用部分子的结合模型来解释。pQCD的计算显示在穿过高温、高密的 QGP时,高能胶子会比高能轻夸克(uds)损失更多的能量,因而 pQCD预言在高 横动量区间,中心对撞事例中重子产额会比介子有更大的压低。而我们的测量结果 显示在高横动量区间,重子产额与介子产额有着相同大小的压低,这一现象揭示了 夸克和胶子在 QGP中的能损(dE/dx)可能与微扰 QCD能损模型的预言不符,从而为 高能部分子在 QGP中的能损机制提供全新的实验现象。 Production of meson, baryon and light nuclei (A=2, 3): investigating freeze-out dynamics and roles of energetic quarks and gluons in Au+Au collisions at RHIC A Dissertation Presented to the Faculty of the Graduate School of University of Science and Technology of China in Candidacy for the Degree of Doctor of Philosophy