Phases of Augmented Hadronic Light-Front Wave Functions

TL;DR

This paper develops a formalism using augmented light-front wave functions with phases depending on boundary conditions, to better understand single-spin asymmetries and diffraction phenomena in QCD, especially through rescattering effects.

Contribution

It introduces a method to incorporate imaginary phases into light-front wave functions, linking initial/final state interactions with observable asymmetries in hadronic processes.

Findings

Calculated the Sivers function from augmented wave functions.

Demonstrated the connection between rescattering phases and naive-time-reversal-odd observables.

Provided insights into factorization properties of transverse momentum dependent distributions.

Abstract

It is an important question whether the final/initial state gluonic interactions which lead to naive-time-reversal-odd single-spin asymmetries and diffraction at leading twist can be associated in a definite way with the light-front wave function hadronic eigensolutions of QCD. We use light-front time-ordered perturbation theory to obtain augmented light-front wave functions which contain an imaginary phase which depends on the choice of advanced or retarded boundary condition for the gauge potential in light-cone gauge. We apply this formalism to the wave functions of the valence Fock states of nucleons and pions, and show how this illuminates the factorization properties of naive-time-reversal-odd transverse momentum dependent observables which arise from rescattering. In particular, one calculates the identical leading-twist Sivers function from the overlap of augmented light-front wavefunctions that one obtains from explicit calculations of the single-spin asymmetry in semi-inclusive deep inelastic lepton-polarized nucleon scattering where the required phases come from the final-state rescattering of the struck quark with the nucleon spectators.