Creation of quark-gluon plasma droplets with three distinct geometries
Creation of quark-gluon plasma droplets with three distinct geometries
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DOI：
10.1038/s41567-018-0360-0
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发表时间：
2019-03-01
期刊：
影响因子：
19.6
通讯作者：
Zou, L.
中科院分区：
文献类型：
--
作者：
Aidala, C.;Akiba, Y.;Zou, L.
相对论能量下重核碰撞的实验研究已经确定了夸克-胶子等离子体（QGP）的性质，这是一种热的、致密的核物质状态，其中夸克和胶子没有束缚成强子（1-4）。在这种状态下，物质表现为几乎无粘性的流体（5），其有效地将初始空间各向异性转化为所产生的粒子之间的相关动量各向异性，从而产生称为集体流的常见速度场模式。近年来，在小系统质子-质子（p+p）和质子-核（p+A）碰撞中测量到了类似的动量各向异性，尽管预期产生的介质的体积和寿命太小而不能形成QGP。本文报道了在核子-核子质心能量根s（NN）= 200 GeV时，质子-金（p+Au）、氘-金（d+Au）和氦-金（He-3+Au）碰撞中产生的椭圆形和三角形带电粒子流图的观测结果。三种不同的初始几何形状和两种流型的独特组合提供了前所未有的模型识别。流体动力学模型，其中包括一个短暂的QGP液滴的形成，提供了最好的同时描述这些测量。
Experimental studies of the collisions of heavy nuclei at relativistic energies have established the properties of the quark-gluon plasma (QGP), a state of hot, dense nuclear matter in which quarks and gluons are not bound into hadrons(1-4). In this state, matter behaves as a nearly inviscid fluid(5) that efficiently translates initial spatial anisotropies into correlated momentum anisotropies among the particles produced, creating a common velocity field pattern known as collective flow. In recent years, comparable momentum anisotropies have been measured in small-system proton-proton (p+p) and proton-nucleus (p+A) collisions, despite expectations that the volume and lifetime of the medium produced would be too small to form a QGP. Here we report on the observation of elliptic and triangular flow patterns of charged particles produced in proton-gold (p+Au), deuteron-gold (d+Au) and helium-gold (He-3+Au) collisions at a nucleon-nucleon centre-of-mass energy root s(NN) = 200 GeV. The unique combination of three distinct initial geometries and two flow patterns provides unprecedented model discrimination. Hydrodynamical models, which include the formation of a short-lived QGP droplet, provide the best simultaneous description of these measurements.