The Lanczos Equation on Light-Like Hypersurfaces in a Cosmologically Viable Class of Kinetic Gravity Braiding Theories

Symmetry

Bence Racskó¹  LászlóÁ. Gergely² 

[1] Department of Theoretical Physics, University of Szeged, Tisza L. krt. 84-86, H-6720 Szeged, Hungary;Institute of Physics, University of Szeged, Dóm tér 9, H-6720 Szeged, Hungary;

关键词: scalar–tensor gravity;    junction conditions;    null hypersurfaces;   

DOI  :  10.3390/sym11050616

来源: DOAJ

【 摘 要 】

We discuss junction conditions across null hypersurfaces in a class of scalar−tensor gravity theories (i) with second-order dynamics, (ii) obeying the recent constraints imposed by gravitational wave propagation, and (iii) allowing for a cosmologically viable evolution. These requirements select kinetic gravity braiding models with linear kinetic term dependence and scalar field-dependent coupling to curvature. We explore a pseudo-orthonormal tetrad and its allowed gauge fixing with one null vector standing as the normal and the other being transversal to the hypersurface. We derive a generalization of the Lanczos equation in a 2 + 1 decomposed form, relating the energy density, current, and isotropic pressure of a distributional source to the jumps in the transverse curvature and transverse derivative of the scalar. Additionally, we discuss a scalar junction condition and its implications for the distributional source.

【 授权许可】

Unknown