Brookhaven National Laboratory, Upton, New York 11973.
AGH University of Science and Technology, FPACS, Cracow 30-059, Poland.
Phys Rev Lett. 2019 Oct 18;123(16):162301. doi: 10.1103/PhysRevLett.123.162301.
We report the first measurement of rapidity-odd directed flow (v_{1}) for D^{0} and D^{0}[over ¯] mesons at midrapidity (|y|<0.8) in Au+Au collisions at sqrt[s_{NN}]=200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 10-80% Au+Au collisions, the slope of the v_{1} rapidity dependence (dv_{1}/dy), averaged over D^{0} and D^{0}[over ¯] mesons, is -0.080±0.017(stat)±0.016(syst) for transverse momentum p_{T} above 1.5 GeV/c. The absolute value of D^{0} meson dv_{1}/dy is about 25 times larger than that for charged kaons, with 3.4σ significance. These data give a unique insight into the initial tilt of the produced matter, and offer constraints on the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.
我们首次测量了在相对论重离子碰撞中 Au+Au 碰撞中在 midrapidity(|y|<0.8)处 D^{0}和 D^{0}[over ¯]介子的快度奇向各向流(v_{1})。在 10-80% Au+Au 碰撞中，D^{0}和 D^{0}[over ¯]介子的 v_{1}快度依赖的斜率(dv_{1}/dy)，在横动量 p_{T}大于 1.5 GeV/c 时，平均为 -0.080±0.017(stat)±0.016(syst)。D^{0}介子 dv_{1}/dy 的绝对值大约是带电 K 介子的 25 倍，具有 3.4σ 的显著性。这些数据为初始产生物质的倾斜提供了独特的见解，并为相对论重离子碰撞中产生的热 QCD 介质的几何和输运参数提供了限制。
