| Nucleon structure,a frontier of high-energy nuclear physics,has been studied for half a century.Motivated by the proposed electron-ion collider,there is a need for more reliable and precise information about nucleon structure,especially concerning the distribution of gluons and sea quarks.However,only a few approaches,such as lattice QCD,can provide the gluon and quark distributions.Basis light-front quantization(BLFQ)is one of the most promising tools to solve for the nonperturbative quantum field theory,eigenstates can be used to study the bound states in quantum chromodynamics.With this goal,we employed BLFQ to investigate nucleon structure and compared it with experimental data and calculations using other methods.In our first calculation,we expanded the nucleon state in the leading Fock sector(|qqq>)and constructed the effective Hamiltonian with the transverse and longitudinal confining potential and the one-gluon exchange interaction.Then,diagonalizing the Hamiltonian matrix,we obtained the light-front wave functions(LFWFs)and calculated various distribution functions,such as parton distribution functions(PDFs),form factors(FFs),and generalized parton distribution functions(GPDs).We also predicted the charge and radius of the nucleon.We found that BLFQ results more or less agree with the experimental data and global fit results.It is worth mentioning that BLFQ led to a charge radius of 0.80±0.04 fm,which agrees with the newest experimental result of 0.833±0.010 fm.However,only considering the leading Fock sector contributions,we found that polarized parton distribution functions somewhat deviate from the global fit results.To study the nucleon structure more precisely,we included a higher Fock sector(|qqq>+|qqqg>).Meanwhile,we replaced one-gluon exchange with the QCD vertex interaction and instantaneous gluon-exchange interactions.Using the LFWFs of the nucleon by diagonalizing the Hamiltonian matrix,we calculated the PDFs,FFs,and GPDs.In a recent work,by fitting the valence quark distribution functions to experimental data and global fit results,we have studied the gluon distribution.As we include the higher Fock sector,we found that the gluon PDF at the experimental scale is closer to the global fit results.The helicity PDF and axial FFs show good improvement compared with previous work.We found a contribution of the gluon spin to the nucleon around 26%,which is closer to the COMPASS data(40%)and the NNPDF results including the STAR data(～42%)from the previous results based on the one gluon-exchange effective interactions. |
