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arXiv 1910.01201hep-exnucl-ex
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STAR质子-质子纵向极化碰撞中胶子极化的测量

Gluon polarization measurements from longitudinally polarized proton-proton collisions at STAR

Zilong Chang

摘要:

RHIC运动学条件下$pp$碰撞在赝快度范围$-1.0 < η< 1.0$内产生的喷流主要由夸克-胶子和胶子-胶子散射过程控制。因此喷注的纵向双自旋不对称性$A_{LL}$是研究质子中胶子纵向极化的有效途径。在STAR,射流是在全方位重建,从带电粒子轨道所看到的时间投影室和电磁能量沉积在桶和端盖电磁量能器在$\sqrt{s} = $ 200和510 GeV。在$\sqrt{s} = $ 200 GeV的早期STAR包容喷流$A_{LL}$结果提供了在$x > $ 0.05的非零胶子极化的第一个证据。在$\sqrt{s} = $ 510 GeV处,包含喷流$A_{LL}$对低至$x \sim $ 0.015的胶子极化敏感。在这次演讲中,我们将讨论最近在$\sqrt{s} = $ 510 GeV的STAR包含喷流和双喷流$A_{LL}$结果,并强调为这种分析设计的新技术,例如对喷流横向能量的潜在事件校正及其对喷流$A_{LL}$的影响。Dijet的$A_{LL}$结果显示为四个拓扑结构的伪快度区域,有效地扫描的$x$依赖的胶子极化。

英文摘要:

Jets produced in the pseudo-rapidity range, $-1.0 < η< 1.0$, from $pp$ collisions at RHIC kinematics are dominated by quark-gluon and gluon-gluon scattering processes. Therefore the longitudinal double spin asymmetry $A_{LL}$ for jets is an effective channel to explore the longitudinal gluon polarization in the proton. At STAR, jets are reconstructed in full azimuth, from the charged-particle tracks seen by the Time Projection Chamber and electro-magnetic energy deposited in the Barrel and Endcap electro-magnetic calorimeters at both $\sqrt{s} = $ 200 and 510 GeV. Early STAR inclusive jet $A_{LL}$ results at $\sqrt{s} = $ 200 GeV provided the first evidence of the non-zero gluon polarization at $x > $ 0.05. At $\sqrt{s} = $ 510 GeV, the inclusive jet $A_{LL}$ is sensitive to the gluon polarization as low as $x \sim $ 0.015. In this talk, we will discuss recent STAR inclusive jet and dijet $A_{LL}$ results at $\sqrt{s} = $ 510 GeV and highlight the new techniques designed for this analysis, for example the underlying event correction to the jet transverse energy and its effect on the jet $A_{LL}$. Dijet $A_{LL}$ results are shown for four topologies in regions of pseudo-rapidity, effectively scanning the $x$-dependence of the gluon polarization.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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