Revisiting chameleon gravity - thin-shells and no-shells with appropriate boundary conditions

Takashi Tamaki; Shinji Tsujikawa

doi:10.1103/PhysRevD.78.084028

paper

Revisiting chameleon gravity - thin-shells and no-shells with appropriate boundary conditions

arXiv:0808.2284 · doi:10.1103/PhysRevD.78.084028

Abstract

We derive analytic solutions of a chameleon scalar field $ϕ$ that couples to a non-relativistic matter in the weak gravitational background of a spherically symmetric body, paying particular attention to a field mass $m_{A}$ inside of the body. The standard thin-shell field profile is recovered by taking the limit $m_{A} * r_{c} \to \infty$ , where $r_{c}$ is a radius of the body. We show the existence of "no-shell" solutions where the field is nearly frozen in the whole interior of the body, which does not necessarily correspond to the "zero-shell" limit of thin-shell solutions. In the no-shell case, under the condition $m_{A} * r_{c} ≫ 1$ , the effective coupling of $ϕ$ with matter takes the same asymptotic form as that in the thin-shell case. We study experimental bounds coming from the violation of equivalence principle as well as solar-system tests for a number of models including $f (R)$ gravity and find that the field is in either the thin-shell or the no-shell regime under such constraints, depending on the shape of scalar-field potentials. We also show that, for the consistency with local gravity constraints, the field at the center of the body needs to be extremely close to the value $ϕ_{A}$ at the extremum of an effective potential induced by the matter coupling.

14 pages, no figures

Revisiting chameleon gravity - thin-shells and no-shells with appropriate boundary conditions

Abstract

References in corpus (59)

Cited by in corpus (46)