Revisiting helicity parton distributions at a future electron-ion collider
Revisiting helicity parton distributions at a future electron-ion collider
复制标题
重新审视未来电子离子对撞机的螺旋度部分子分布
作者：
I. Borsa;G. Lucero;R. Sassot;E. Aschenauer;A. S. Nunes
我们研究了未来电子离子对撞机包含和半包含极化深度非弹性散射数据对确定螺旋度部分子分布的影响。在DSSV14分析的蒙特卡罗采样变体中，我们发现在确定螺旋度分布方面有了显著的改进，我们使用了具有更新不确定性估计的极化包涵和半包涵电子-质子深度非弹性散射的伪数据，以及两个不同质心系统能量（分别为$\sqrt{s}=44.7$ GeV和$\sqrt{s}=141.4$ GeV）和$\sqrt{s}=115.2$ GeV的包涵电子-氦碰撞的伪数据。特别是在低部分动量分数$x$。虽然包含电子-质子的最低能量组态数据将胶子极化显著地限制在$x \sim 10^{-4}$，但更高的能量组态加强了约束并将其进一步延长了10年。另一方面，半包容性数据实现了迄今为止难以捉摸的海夸克风味分离，这是任何其他包容性电磁测量都无法获得的。与氦的碰撞补充了包含质子的测量，将夸克加反夸克$u, d$和$s$组合极化的限制推到了前所未有的水平。
We studied the impact of future Electron Ion Collider inclusive and semi-inclusive polarized deep inelastic scattering data will have on the determination of the helicity parton distributions. Supplementing the Monte Carlo sampling variant of the DSSV14 analysis with pseudo-data on polarized inclusive and semi-inclusive electron-proton deep inelastic scattering with updated uncertainty estimates and for two different center-of-mass-system energies, $\sqrt{s}=44.7$ GeV and $\sqrt{s}=141.4$ GeV respectively, and on inclusive electron-helium collisions at $\sqrt{s}=115.2$ GeV, we find a remarkable improvement in the determination of the helicity distributions, specially at low parton momentum fraction $x$. While inclusive electron-proton data at the lowest energy configuration constrain significantly the gluon polarization down to $x \sim 10^{-4}$, the higher energy configuration strengthens the constraint and extends it one decade further. On the other hand, semi-inclusive data achieves the hitherto elusive flavor separation for sea quarks that can not be obtained from any other inclusive electromagnetic measurement. Collisions with helium complement inclusive proton measurements, pushing the constraints on the combined quark plus anti-quark $u, d$ and $s$ polarizations to an unprecedented level.