Raychaudhuri and optical equations for null geodesic congruences with torsion

2018/08/02 by Simone Speziale · 1 voice
Physics and Astronomy · #gr-qc #hep-th

paper · pdf · doi:10.1103/physrevd.98.084029

published as Phys. Rev. D 98, 084029 (2018) · v2: improved text, a few equations and a subsection added. v3: typo in one equation corrected, improved conclusions and other minor amendments

arxiv published 2018/08/02 · arxiv created 2018/10/16 · arxiv updated 2018/10/24

Abstract

We study null geodesic congruences (NGCs) in the presence of spacetime torsion, recovering and extending results in the literature. Only the highest spin irreducible component of torsion gives a proper acceleration with respect to metric NGCs, but at the same time obstructs abreastness of the geodesics. This means that it is necessary to follow the evolution of the drift term in the optical equations, and not just shear, twist and expansion. We show how the optical equations depend on the non-Riemannian components of the curvature, and how they reduce to the metric ones when the highest spin component of torsion vanishes.

Discussions

• I am reading Raychaudhuri equation from this https://arxiv.org/abs/1808.00952v3 paper but I have read other literature too in which they say expansion scalar $\theta$ is area element in Raychaudhuri e [stackexchange, 0 points]

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