5.02 TeV下全流体控制：超SONIC模型揭示p+p、p+Pb与Pb+Pb碰撞的粘性动力学

30 浏览量更新于2024-09-06 收藏 941KB PDF 举报

本文主要探讨了在s = 5.02 TeV能量下，通过superSONIC模型对中心p + p、p + Pb和Pb + Pb碰撞中的流体行为进行逐事件模拟。superSONIC模型是一个综合性的框架，它将预平衡流、粘性流体动力学演化以及后期强子散射过程结合起来，以提供对高能核碰撞中物质生成的细致描述。模型的核心是基于Monte Carlo Glauber模型的扩展，这个模型假设每个核子包含三个构成夸克。这样做的目的是为了捕捉到在这些碰撞中不同系统的特性，如局部热化程度和动态响应。通过这种通用化的处理方式，superSONIC能够在不同的碰撞系统中统一描述流体动力学参数，如剪切粘度和体积粘度，这有助于我们理解这些参数如何影响碰撞过程中形成的流型。焦点集中在实验观测到的椭圆流（elliptic flow）和三角流（triangular flow），这是高能核碰撞中重要的动量分布模式，它们与系统的几何形状和非平衡动力学有关。实验数据表明，在p + p、p + Pb和Pb + Pb这样的碰撞中，尽管系统规模和复杂性各异，但流体动力学效应显示出统一的特征，这暗示着这些现象可能有着共同的水动力起源。通过这种方法，研究者能够揭示出在极端条件下，物质的行为模式是如何遵循流体动力学定律的，并且验证了这些定律在不同尺度和能量范围内的普遍性。这项工作不仅有助于深化我们对基本物理原理的理解，也对建立更精确的理论模型和解析实验数据提供了强有力的工具。这篇文章的重要贡献在于，它通过superSONIC模型对高能核碰撞中的流体动力学行为进行了深入分析，揭示了即使在最小的p + p碰撞到最大的Pb + Pb碰撞中，粘性流体动力学规律的普适性，为理解量子色动力学（QCD）在极高温和高密度条件下的表现提供了新的见解。

Physics Letters B 774 (2017) 351–356

Contents lists available at ScienceDirect

Physics Letters B

www.elsevier.com/locate/physletb

One ﬂuid to rule them all: Viscous hydrodynamic description of

event-by-event central p+p, p+Pb and Pb+Pb collisions at

√

s =5.02 TeV

Ryan D. Weller

, Paul Romatschke

a,b,∗

Department of Physics, University of Colorado, Boulder, CO 80309, USA

Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA

a r t i c l e i n f o a b s t r a c t

Article history:

Received

18 August 2017

Accepted

26 September 2017

Available

online 28 September 2017

Editor:

J.-P. Blaizot

The matter created in central p+p, p+Pb and Pb+Pb collisions at

√

s = 5.02 TeV is simulated event-

by-event

using the superSONIC model, which combines pre-equilibrium ﬂow, viscous hydrodynamic

evolution and late-stage hadronic rescatterings. Employing a generalization of the Monte Carlo Glauber

model where each nucleon possesses three constituent quarks, superSONIC describes the experimentally

measured elliptic and triangular ﬂow at central rapidity in all systems using a single choice for the

ﬂuid parameters, such as shear and bulk viscosities. This suggests a common hydrodynamic origin of the

experimentally observed ﬂow patterns in all high energy nuclear collisions, including p+p.

(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP

1. Introduction

What are the properties of the matter created in ultrarelativis-

tic

ion collisions? Obtaining an answer to this question has been

one of the key goals of the high energy nuclear physics com-

munity

and the driving force behind the experimental heavy-ion

program at both the Relativistic Heavy Ion Collider (RHIC) and the

Large Hadron Collider (LHC). Much progress has been made, such

as the realization that the matter created in heavy-ion collisions

behaves more like a strongly interacting ﬂuid, rather than a gas

of weakly-interacting quarks and gluons [1–4]. Some properties of

this strongly interacting QCD ﬂuid, such as the shear viscosity co-

eﬃcient

and the local speed of sound, have since been constrained

from model–data comparison and ﬁrst-principles QCD calculations

alike [5–12]. Others, such as the minimum possible size for a

QCD ﬂuid droplet, remain yet to be unambiguously determined.

Before the present decade, the mainstream expectation was that

a strongly interacting QCD ﬂuid could only be formed in “large”

systems, such as those created in heavy-ion collisions. “Small” sys-

tems,

such as those formed in proton+nucleus or proton+pro-

ton

collisions, were not expected to ﬂow. It thus came as a sur-

prise

to many when experimental data from proton+nucleus and

Corresponding author.

E-mail

address: paul.romatschke@colorado.edu (P. Romatschke).

proton+proton collisions both at RHIC and the LHC unambiguously

demonstrated the existence of ﬂow in these small systems [13–17].

The

focus of the theory community has since shifted towards

understanding the origin of experimentally observed ﬂow sig-

nals

in small systems. At present, there are two main schools of

thought. One maintains that while experimental evidence leaves

no doubt that there are ﬂow-like signals in small systems, these

signals are unrelated to those observed in heavy-ion collisions

and are caused by either initial-state correlations [18–24], or non-

hydrodynamic

evolution, or non-standard ﬁnal-state interactions

[25–29] or a combination of these. The other school of thought, on

which the present work will be based, adheres to Heraclit’s princi-

ple

of “Panta Rhei” (“Everything Flows”). According to Panta Rhei,

there is no fundamental difference between the experimental ﬂow

signals in small and large systems, and both can be quantitatively

explained using the laws of hydrodynamics. (See Refs. [30,31] for

a discussion of why non-equilibrium hydrodynamics may be appli-

cable

to QCD ﬂuid droplets as small as 0.15 fm.) Previous work on

this subject includes the prediction of ﬂow signals in p+p [32–35],

p+Pb [35,36],

He+Au [37,38], p+Au and d+Au collisions [39] as

well as the hydrodynamic description of low momentum exper-

imental

data in small systems (see e.g. Refs. [40–42] for recent

examples).

One

of the main criticisms of the Panta Rhei approach to rela-

tivistic

ion collisions has been that a hydrodynamic description of

experimental data of one or two individual collision systems could

https://doi.org/10.1016/j.physletb.2017.09.077

0370-2693/

SCOAP

下载后可阅读完整内容，剩余5页未读，立即下载

weixin_38605538

粉丝: 4
资源: 991

5.02 TeV下全流体控制：超SONIC模型揭示p+p、p+Pb与Pb+Pb碰撞的粘性动力学

集成水动力模型中CERN大型强子对撞机在sNN = 5.02TeV时Pb + Pb碰撞中的体积可观观测

sNN = 5.02 TeV时p + Pb碰撞中热介质对J /ψ产生的影响

径向流对两个粒子相关性的影响，在sNN = 5.02 TeV的pâPb碰撞中，在中间p T具有已确定的触发条件

5.02 TeV中心p + Pb碰撞中的介子干涉测量研究

中心p + Pb碰撞中的干涉测量相关性

轻离子碰撞：平衡前QCD动力学的窗口？

Xe-Xe碰撞中带电粒子的横向动量谱和核修饰因子

来自纯非流体动力传输的高动量方位角各向异性

相对论输运方法研究LHC的集体各向异性$$ v_2 $$ v2和$$ v_3 $$ v3及其在pA碰撞中的波动

大型强子对撞机中质子-铅碰撞中波动的质子形状的印迹

最新资源