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arXiv · 2108.03301

Unified formalism for electromagnetic and gravitational probes: densities

Adam Freese·Gerald A. Miller
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Abstract

The use of light front coordinates allows a fully relativistic description of a hadron's spatial densities to be obtained. These densities must be two-dimensional and transverse to a chosen spatial direction. We explore their relationship to the three-dimensional, non-relativistic densities, with a focus on densities associated with the energy momentum tensor. The two-dimensional non-relativistic densities can be obtained from the light front densities through a non-relativistic limit, and can subsequently be transformed into three-dimensional non-relativistic densities through an inverse Abel transform. However, this operation is not invertible, and moreover the application of the inverse Abel transform to the light front densities does not produce a physically meaningful result. We additionally find that the Abel transforms of so-called Breit-frame densities generally differ significantly from the true light front densities. Numerical examples are provided to illustrate the various differences between the light front, Breit frame, and non-relativistic treatment of densities.

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Adam Freese, Gerald A. Miller. 2021-08-06. Unified formalism for electromagnetic and gravitational probes: densities. https://doi.org/10.1103/physrevd.105.014003

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