Conical singularities and the Vainshtein screening in full GLPV theories

Ryotaro Kase; Shinji Tsujikawa; Antonio De Felice

doi:10.1088/1475-7516/2016/03/003

paper

Conical singularities and the Vainshtein screening in full GLPV theories

arXiv:1512.06497 · doi:10.1088/1475-7516/2016/03/003

Abstract

In Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories, it is known that the conical singularity arises at the center of a spherically symmetric body ( $r = 0$ ) in the case where the parameter $α_{H 4}$ characterizing the deviation from the Horndeski Lagrangian $L_{4}$ approaches a non-zero constant as $r \to 0$ . We derive spherically symmetric solutions around the center in full GLPV theories and show that the GLPV Lagrangian $L_{5}$ does not modify the divergent property of the Ricci scalar $R$ induced by the non-zero $α_{H 4}$ . Provided that $α_{H 4} = 0$ , curvature scalar quantities can remain finite at $r = 0$ even in the presence of $L_{5}$ beyond the Horndeski domain. For the theories in which the scalar field $ϕ$ is directly coupled to $R$ , we also obtain spherically symmetric solutions inside/outside the body to study whether the fifth force mediated by $ϕ$ can be screened by non-linear field self-interactions. We find that there is one specific model of GLPV theories in which the effect of $L_{5}$ vanishes in the equations of motion. We also show that, depending on the sign of a $L_{5}$ -dependent term in the field equation, the model can be compatible with solar-system constraints under the Vainshtein mechanism or it is plagued by the problem of a divergence of the field derivative in high-density regions.

arXiv comment25 pages, 1 figure

Conical singularities and the Vainshtein screening in full GLPV theories

Abstract

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