Alexandrou Constantia, Constantinou Martha, Hadjiyiannakou Kyriakos, Jansen Karl, Manigrasso Floriano
Department of Physics, University of Cyprus, P.O. Box 20537, Nicosia 1678, Cyprus.
Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Kavafi Street, Nicosia 2121, Cyprus.
Phys Rev Lett. 2021 Mar 12;126(10):102003. doi: 10.1103/PhysRevLett.126.102003.
We present, for the first time, an ab initio calculation of the individual up, down, and strange quark helicity parton distribution functions for the proton. The calculation is performed within the twisted mass clover-improved fermion formulation of lattice QCD. The analysis is performed using one ensemble of dynamical up, down, strange, and charm quarks with a pion mass of 260 MeV. The lattice matrix elements are nonperturbatively renormalized and the final results are presented in the MS[over ¯] scheme at a scale of 2 GeV. We give results for Δu^{+}(x), Δd^{+}(x) Δu^{-}(x), Δd^{-}(x), including disconnected quark loop contributions, as well as for Δs^{+}(x) and Δs^{-}(x). For the latter we achieve unprecedented precision compared to the phenomenological estimates.
我们首次给出了质子的单个上夸克、下夸克和奇夸克螺旋度部分子分布函数的从头计算。该计算是在晶格量子色动力学的扭质量三叶草改进费米子公式内进行的。分析使用了一组动态上夸克、下夸克、奇夸克和粲夸克，其π介子质量为260 MeV。晶格矩阵元进行了非微扰重整化，最终结果以MS[上划线]方案在2 GeV的标度下给出。我们给出了Δu⁺(x)、Δd⁺(x)、Δu⁻(x)、Δd⁻(x)的结果，包括断开的夸克圈贡献，以及Δs⁺(x)和Δs⁻(x)的结果。与唯象估计相比，对于后者我们达到了前所未有的精度。
