共查询到18条相似文献,搜索用时 109 毫秒
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用相对论输运模型模拟了束流动能为520MeV/u的238U+238U碰撞实验. 研究了在两种极端对撞方位的UU碰撞中, 末态核子和π介子椭圆流v2与碰撞参数、快度以及横动量的依赖关系. 研究表明, 由于挤压(squeeze-out)效应, 末态核子和π具有负的椭圆流; 体-体UU中心碰撞事件具有最大初始坐标空间形变, 因而具有最大的负的椭圆流, 约12%; 在最小无偏事件样本下, 体-体和头-头碰撞, 中央快度平台上的核子椭圆流大小相当, 而前者π椭圆流略大于后者; 在中央快度平台, 低横动量核子和π主要由反应后期Δ衰变得到, 而高横动量主要是参与核子再散射生成, 因而在低横动量区它们具有相似的流, 而在较高横动量区(>0.3GeV/c)由于旁观核子的再散射和吸收效应, 它们的椭圆流有明显压低. 相似文献
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最近,STAR合作体在相对论重离子对撞机的束流能量扫描实验中观测到了正反粒子的椭圆流劈裂。基于输运模型,发现丰重子介质中正反粒子平均场势的不同可以解释其椭圆流的劈裂。利用Nambu-Jona-Lasinio模型描述相对论重离子碰撞的部分子相,发现实验中正反粒子的相对椭圆流劈裂可以用来约束该模型中夸克矢量相互作用的耦合系数。这一发现对确定QCD相图的临界点位置和理解整个QCD的相结构有重要意义。 相似文献
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Emil AvsarChristoffer Flensburg Yoshitaka Hatta Jean-Yves OllitraultTakahiro Ueda 《Physics letters. [Part B]》2011,702(5):394-397
It has been argued that high-multiplicity proton-proton collisions at the LHC may exhibit collective phenomena usually studied in the context of heavy-ion collisions, such as elliptic flow. We study this issue using DIPSY—a Monte Carlo event generator based on the QCD dipole model. We calculate the eccentricity of the transverse area defined by the spatial distribution of produced gluons. The resulting elliptic flow is estimated to be about 6%, comparable to the value in nucleus-nucleus collisions at RHIC and the LHC. Experimentally, elliptic flow is inferred from the azimuthal correlation between hadrons, which receives contributions from collective flow, and from various other effects referred to as “nonflow”. We discuss how to identify in experiments the signal of flow in the presence of large nonflow effects. 相似文献
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A method for investigating the azimuthal correlations between directed and elliptic flow in heavy ion collisions is described.The transverse anisotropy of particle emission at AGS energies is investigated within the RQMD model.It is found that the azimuthal correlations between directed and elliptic flow are sensitive to the incident energy and impact parameter.The fluctuations in the initial stage and dynamical evolution of heavy ion collisions are not negligible. 相似文献
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A method for investigating the azimuthal correlations between directed and elliptic flow in heavy ion collisions is described. The transverse anisotropy of particle emission at AGS energies is investigated within the RQMD model. It is found that the azimuthal correlations between directed and elliptic flow are sensitive to the incident energy and impact parameter. The fluctuations in the 相似文献
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G. Kh Eyyubova V. L. Korotkikh I. P. Lokhtin S. V. Petrushanko L. I. Sarycheva A. M. Snigirev D. Krofcheck 《Indian Journal of Physics》2011,85(1):63-68
The azimuthal anisotropy of charged particles in heavy ion collisions is an important probe of quark-gluon plasma evolution
at early stages. The nuclear reaction plane can be determined independently by different detector subsystems and using different
analysis methods. This paper reports the capability of the CMS detector at the LHC to reconstruct the reaction plane of the
collision and to me asure elliptic flow with calorimetry and a tracking system. The analysis is based on a full CMS detector
simulation of Pb + Pb events with the HYDJET event generator. 相似文献
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Charge separation is an important consequence of the Chiral Magnetic Effect. Within the framework of a Multi-Phase Transport model, the effects of final state interactions on initial charge separation are studied. We demonstrate that charge separation can be significantly reduced by the evolution of the Quark–Gluon Plasma produced in relativistic heavy ion collisions. Hadronization and resonance decay can also affect charge separation. Moreover, our results show that the Chiral Magnetic Effect leads to the modification of the relation between the charge azimuthal correlation and the elliptic flow that is expected from transverse momentum conservation only. The transverse momentum and pseudorapidity dependences and the effects of background on the charge azimuthal correlation are also discussed. 相似文献
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A new mechanism for the generation of an azimuthal anisotropy of particles produced in heavy-ion collisions is analyzed. An analysis is performed within Reggeon theory and is general. The resulting effect can be interpreted in terms of the partonic structure of a fast nucleus. This mechanismcan contribute significantly to the observed value of the elliptic flow υ 2. The dynamics in question differs significantly from a standard mechanism of the collective motion of a hadron medium after a collision.
相似文献18.
B. Toczek 《Indian Journal of Physics》2011,85(7):1143-1147
Study of particle azimuthal anisotropies, quantified by coefficients of the Fourier decomposition of the azimuthal angle distributions,
has emerged as an important tool to probe the early stages of nucleusnucleus collisions. In this paper the ATLAS capability
of measuring elliptic flow, the second Fourier coefficient, is presented. It is shown that various analysis techniques can
be applied for different combinations of the detector sub-systems. A systematic comparison of various analysis methods is
also shown. 相似文献