Computing light-front wave functions without light-front quantization: A large-momentum effective theory approach
Xiangdong Ji (Center for Nuclear Femtography, SURA, 1201 New York Avenue, Northwest Washington, Washington, DC 20005, USA and Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742, USA); Yizhuang Liu (Institute of Theoretical Physics, Jagiellonian University, 30-348 Kraków, Poland)
Light-front wave functions play a fundamental role in the light-front quantization approach to QCD and hadron structure. However, a naive implementation of the light-front quantization suffers from various subtleties including the well-known zero-mode problem, the associated rapidity divergences which mixes ultraviolet divergences with infrared physics, as well as breaking of spatial rotational symmetry. We advocate that the light-front quantization should be viewed as an effective theory in which small modes have been effectively “integrated out,” with an infinite number of renormalization constants. Instead of solving light-front quantized field theories directly, we make the large momentum expansion of the equal-time Euclidean correlation functions in instant quantization as an effective way to systematically calculate light-front correlations, including the light-front wave function amplitudes. This large-momentum effective theory accomplishes an effective light-front quantization through lattice QCD calculations. We demonstrate our approach using an example of a pseudoscalar meson wave function.
