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arXiv · 1707.06313

Rigorous constraints on the matrix elements of the energy-momentum tensor

Peter Lowdon·Kelly Yu-Ju Chiu·Stanley J. Brodsky
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Abstract

The structure of the matrix elements of the energy-momentum tensor play an important role in determining the properties of the form factors $A(q^{2})$, $B(q^{2})$ and $C(q^{2})$ which appear in the Lorentz covariant decomposition of the matrix elements. In this paper we apply a rigorous frame-independent distributional-matching approach to the matrix elements of the Poincar\'{e} generators in order to derive constraints on these form factors as $q \rightarrow 0$. In contrast to the literature, we explicitly demonstrate that the vanishing of the anomalous gravitomagnetic moment $B(0)$ and the condition $A(0)=1$ are independent of one another, and that these constraints are not related to the specific properties or conservation of the individual Poincar\'{e} generators themselves, but are in fact a consequence of the physical on-shell requirement of the states in the matrix elements and the manner in which these states transform under Poincar\'{e} transformations.

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Peter Lowdon, Kelly Yu-Ju Chiu, Stanley J. Brodsky. 2017-07-19. Rigorous constraints on the matrix elements of the energy-momentum tensor. https://doi.org/10.1016/j.physletb.2017.09.050

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