论文标题
在LHC处与爱丽丝的载体介体的自旋比对测量值
Spin alignment measurements of vector mesons with ALICE at LHC
论文作者
论文摘要
我们介绍了与$ \ mathrm {k^{*0}} $和$ \ mathrmϕ $ vector mesons的旋转对齐相关的测量值，用于$ \ sqrt {s _ {\ sqrt {s _ {\ mathrm {nn}}} $ 2.76 $ = 2.76 tever的pb-pb碰撞。第二个对角线旋转密度矩阵元件（$ρ_{00} $）是根据事件平面和生产平面在衰减休息框中的vector介子衰减女儿的角度分布中测量的。对于两个向量中的媒介，发现$ρ_{00} $值在低$ p _ {\ mathrm {t}} $（$ <$ <$ 2 GEV/$ c $）时发现$ρ_{00} $值小于1/3。观察到的1/3偏差是中部中部碰撞的最大偏差，在3 $σ$的水平上，$ \ mathrm {k^{*0}} $和2 $σ$对于$ \ mathrm钱$梅森。作为对照测量，发现\ rh〜值与1/3一致，即没有显着的自旋比对，用于与生产平面相对于PP碰撞。结果在质量上与将自旋比对归因于夸克极化的模型的期望在质量上是一致的，该模型在存在较大的初始角动量的情况下以及随后通过重组过程的强调。
We present the measurements related to the spin alignment of $\mathrm{K^{*0}}$ and $\mathrmϕ$ vector mesons at mid-rapidity for Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV using the ALICE detector at the LHC. The second diagonal spin density matrix element ($ρ_{00}$) is measured from the angular distribution of the decay daughters of the vector meson in the decay rest frame, with respect to the event plane and the production plane. The $ρ_{00}$ values are found to be less than 1/3 at low $p_{\mathrm{T}}$ ($<$ 2 GeV/$c$) for both vector mesons. The observed deviations from 1/3 are maximal for mid-central collisions at a level of 3$σ$ for $\mathrm{K^{*0}}$ and 2$σ$ for $\mathrmϕ$ mesons. As a control measurement the \rh~values were found to be consistent with 1/3, i.e., no significant spin alignment, for pp collisions with respect to the production plane. The results are qualitatively consistent with the expectation from a model that attributes the spin alignment to a polarization of quarks in the presence of large initial angular momentum and a subsequent hadronization by the process of recombination.
