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In this work we address three issues associated with orbital angular momentum relevant for leading twist polarized deep inelastic scattering. We consider internal orbital helicity of a composite system in an arbitrary reference frame and contrast the results in the non-relativistic situation versus the light-front (relativistic) case. We introduce quark and(More)
We address the long standing problem of the construction of relativistic spin operators for a composite system in QCD. Exploiting the kinematical boost symmetry in light front theory, we show that transverse spin operators for massless particles can be introduced in an arbitrary reference frame, in analogy with those for massive particles. In light front(More)
In these lectures we hope to provide an elementary introduction to selected topics in light-front dynamics. Starting from the study of free field theories of scalar boson, fermion, and massless vector boson, the canonical field commuta-tors and propagators in the instant and front forms are compared and contrasted. Poincare algebra is described next where(More)
Issues related with microcausality violation and continuum limit in the context of (1+1) dimensional scalar field theory in discretized light-cone quanti-zation (DLCQ) are addressed in parallel with discretized equal time quanti-zation (DETQ) and the fact that Lorentz invariance and microcausality are restored if one can take the continuum limit properly is(More)
We investigate the feasibility of analyzing deep inelastic structure functions in Hamiltonian formalism by combining the light-front BJL limit of high energy amplitudes and the Fock space (multi-parton) description of hadrons. This study is motivated by some of the theoretical questions emerging from the ongoing nonperturbative/perturbative studies in(More)
Investigations have revealed a very complex structure for the coefficient functions accompanying the divergences for individual time (x +) ordered diagrams in light-front perturbation theory. No guidelines seem to be available to look for possible mistakes in the structure of these coefficient functions emerging at the end of a long and tedious calculation,(More)
We investigate the twist four longitudinal structure function F τ =4 L of deep inelastic scattering and show that the integral of F τ =4 L x is related to the expectation value of the fermionic part of the light-front Hamiltonian density at fixed momentum transfer. We show that the new relation, in addition to providing physical intuition on F τ =4 L ,(More)
Recently, we have introduced a unified theory to deal with perturbative and non-perturbative QCD contributions to hadronic structure functions in deep inelastic scattering. This formulation is realized by combining the coordinate space approach based on light-front current algebra techniques and the momentum space approach based on Fock space expansion(More)
Non-perturbative Hamiltonian light-front quantum field theory presents opportunities and challenges that bridge particle physics and nuclear physics. Fundamental theories, such as Quantum Chromodynmamics (QCD) and Quantum Electrodynamics (QED) offer the promise of great predictive power spanning phenomena on all scales from the microscopic to cosmic scales,(More)
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