Nucleon structure from basis light-front quantization

Abstract

We produce the light-front wave functions (LFWFs) of the nucleon from a basis light-front approach in the leading Fock sector representation. We solve for the mass eigenstates from a light-front effective Hamiltonian, which includes a confining potential adopted from light-front holography in the transverse direction, a longitudinal confinement, and a one-gluon exchange interaction with fixed coupling. We then employ the LFWFs to obtain the electromagnetic and axial form factors, the parton distribution functions (PDFs) and the generalized parton distribution functions for the nucleon. The electromagnetic and axial form factors of the proton agree with the experimental data, whereas the neutron form factors deviate somewhat from the experiments in the low momentum transfer region. The unpolarized, the helicity, and the transversity valence quark PDFs, after QCD scale evolution, are fairly consistent with the global fits to the data at the relevant experimental scales. The helicity asymmetry for the down quark also agrees well with the measurements, however, the asymmetry for the up quark shows a deviation from the data, especially in the small x region. We also find that the tensor charge agrees well with the extracted data and the lattice QCD predictions, while the axial charge is somewhat outside the experimental error bar. The electromagnetic radii of the proton, the magnetic radius of the neutron, and the axial radius are in excellent agreement with the measurements, while the neutron charge radius deviates from experiment.

Generalized parton distributions and spin structures of light mesons from a light-front Hamiltonian approach

“…Meanwhile, the peaks along x get shifted to larger values of x with increasing −t similar to that observed in the pion GPD. This seems to be a model independent behavior of the GPDs which has been noticed in other phenomenological models for the pion [12] as well as for the nucleon [115][116][117][118]. We also notice that the GPD E T for the up quark in the kaon exhibits a behavior similar to that observed in the pion, however, the magnitude of E T u in the kaon is larger than that in the pion.…”

Longitudinal dynamics for mesons on the light cone

“…One of the interesting questions is how to generalize the present investigation to the multiparton sectors, including notably the baryons. There have been several proposals in the literature, including the pairwise longitudinal interactions [67,68], the quark-diquark model [21,69], and the orthogonal basis over a k-simplex (triangle, tetrahedron, ...) [24,[70][71][72].…”

Hadron structure from basis light-front quantization

“…( 2), and a onegluon exchange interaction with fixed coupling. [9,10]. The parameters in the effective interaction are fixed by fitting the nucleon mass and the flavor Dirac form factors.…”

“…The parameters in the effective interaction are fixed by fitting the nucleon mass and the flavor Dirac form factors. We then employ the resulting LFWFs to calculate the EMFFs, PDFs, GPDs, TMDs and many other observables of the nucleon [9][10][11].…”