Probing vorticity structure in heavy-ion collisions by local $��$ polarization
| Autor: | Xia, Xiao-Liang, Li, Hui, Tang, Zebo, Wang, Qun |
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| Rok vydání: | 2018 |
| Předmět: | |
| DOI: | 10.48550/arxiv.1803.00867 |
| Popis: | We study the local structure of the vorticity field and the $��$ polarization in Au+Au collisions in the energy range $\sqrt{s_{\mathrm{NN}}}=7.7$--$200$ GeV and Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2760$ GeV using A Multi-Phase Transport (AMPT) model. We focus on the vorticity field arising from the non-uniform expansion of the fireball, which gives the circular structure of the transverse vorticity $\boldsymbol��_{\perp}=(��_{x},��_{y})$ around the $z$ direction as well as the quadrupole pattern of the longitudinal vorticity $��_{z}$ in the transverse plane. As a consequence, the three components of the polarization vector $\mathbf{P}=(P_{x},P_{y},P_{z})$ for $��$ hyperons show harmonic behaviors as $\mathrm{sgn}(Y)\sin��_{p}$, $-\mathrm{sgn}(Y)\cos��_{p}$, and $-\sin(2��_{p})$, where $��_{p}$ and $Y$ are the azimuthal angle and rapidity in momentum space. These patterns of the local $��$ polarization are expected to be tested in future experiments. 8 pages, 7 figures. One table, one figure and references added. Discussions in Sec III and IV improved. To appear in Phys. Rev. C |
| Databáze: | OpenAIRE |
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