Speaker
Xu Sun
(Lawrence Berkeley National Laboratory)
Description
Triangular flow ($v_{3}$), the third harmonic of the azimuthal particle distribution relative to the event plane, is getting more attention in recent years. It is considered that $v_{3}$ is generated by event-by-event initial state fluctuations. Therefore, it is natural to use $v_{3}$ as a tool to study initial state fluctuations and the subsequent evolution of the collision system. Another aspect of identified-particle $v_{3}$ measurements is the study of the energy dependent difference between particles and anti-particles $v_{3}$. That is especially important after the observation of a difference in elliptic flow between particles and anti-particles in Beam Energy Scan data at STAR.
We present $v_{3}$ measurements from STAR of identified particles ($\pi^\pm$, $K^\pm$, $p$, $\bar{p}$, $\phi$, $\Lambda$ and $\bar{\Lambda}$) relative to the third-order event plane as a function of $p_\mathrm{T}$ for different centralities (0\%-80\%, 0\%-10\%, 10\%-40\%, and 40\%-80\%) at $\sqrt{s_\mathrm{NN}} =$ 27 GeV, 39 GeV and 200 GeV. We discuss the hydrodynamics-inspired mass ordering at low $p_\mathrm{T}$ ($p_\mathrm{T} < $ 1.5 GeV/c), number-of-consitituent-quarks scaling at intermediate $p_\mathrm{T}$ (0.5 GeV/c $ < p_\mathrm{T}/n_\mathrm{q} < $ 1.5 GeV/c), and the difference between particles and anti-particles as a function of centrality and beam energy. We also present $v_{3}$ for charged hadrons relative to the first-order event plane which is determined from spectator neutrons at $\sqrt{s_\mathrm{NN}}=$ 200 GeV Au+Au and 193 GeV U+U collisions. As this type of event plane represents the reaction plane instead of the participant plane, it helps us to understand the origin of triangular flow.
| On behalf of collaboration: | STAR |
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Primary author
Xu Sun
(Lawrence Berkeley National Laboratory)
