We obtain the electromagnetic form factors, the axial form factor, and the parton distribution functions of the proton from the eigenstates of a light-front effective Hamiltonian in the leading Fock representation suitable for low-momentum scale applications. The electromagnetic and the axial form factors are found to be in agreement with the available experimental data. The unpolarized, the helicity, and the transversity valence quark distributions, after QCD evolution, are consistent with the global QCD analyses. The tensor charge also agrees the experimental data, while the axial charge is somewhat outside the experimental error bar.
Bibliographical noteFunding Information:
We thank Henry Lamm, Wei Zhu, and Shuai Liu for many useful discussions. C. M. is supported by the National Natural Science Foundation of China (NSFC) under the Grants No. 11850410436 and No. 11950410753. X. Z. is supported by new faculty startup funding by the Institute of Modern Physics, Chinese Academy of Sciences and by Key Research Program of Frontier Sciences, CAS, Grant No. ZDBS-LY-7020. This work of C. M, S. X., J. L, and X. Z. is also supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, Grant No. XDB34000000. The work of D. C. is supported by Science and Engineering Research Board under Grant No. CRG/2019/000895. J. P. V. is supported by the Department of Energy under Grants No. DE-FG02-87ER40371, and No. DE-SC0018223 (SciDAC4/NUCLEI). A portion of the computational resources were provided by the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE- AC02-05CH11231.