English

The gauge-invariant canonical energy-momentum tensor

High Energy Physics - Phenomenology 2016-04-20 v1

Abstract

The canonical energy-momentum tensor is often considered as a purely academic object because of its gauge dependence. However, it has recently been realized that canonical quantities can in fact be defined in a gauge-invariant way provided that strict locality is abandoned, the non-local aspect being dictacted in high-energy physics by the factorization theorems. Using the general techniques for the parametrization of non-local parton correlators, we provide for the first time a complete parametrization of the energy-momentum tensor (generalizing the purely local parametrizations of Ji and Bakker-Leader-Trueman used for the kinetic energy-momentum tensor) and identify explicitly the parts accessible from measurable two-parton distribution functions (TMDs and GPDs). As by-products, we confirm the absence of model-independent relations between TMDs and parton orbital angular momentum, recover in a much simpler way the Burkardt sum rule and derive three similar new sum rules expressing the conservation of transverse momentum.

Keywords

Cite

@article{arxiv.1601.01938,
  title  = {The gauge-invariant canonical energy-momentum tensor},
  author = {Cédric Lorcé},
  journal= {arXiv preprint arXiv:1601.01938},
  year   = {2016}
}

Comments

6 pages, contribution to the proceedings of the POETIC 2015 Conference, Sep 7-11, Ecole polytechnique, Palaiseau, France