Cosmology with a successful Vainshtein screening in theories beyond Horndeski
Cosmology with a successful Vainshtein screening in theories beyond Horndeski
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DOI：
10.1103/physrevd.93.024007
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发表时间：
2015-10
影响因子：
5
通讯作者：
R. Kase;S. Tsujikawa;A. D. Felice
中科院分区：
文献类型：
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作者：
R. Kase;S. Tsujikawa;A. D. Felice
我们提出了一个暗能量模型，在这个模型中，标量场与Ricci标量之间存在膨胀耦合，它具有非线性的自相互作用。这属于霍恩德斯基以外的理论的一个子类，它将协变的伽利翁理论和布兰斯-狄克理论作为具体案例。我们得到了从辐射时代到今天，标量声速平方${c}{\mathm{S}}^{2}$为正的条件。由于${c}{\mathm{S}}^{2}$仍然小于1的量级，因此偏离Horndeski理论不会引起规范不变引力势的剧烈振荡。在这种情况下，物质微扰在低红移时的演化类似于在引力相互作用增强的耦合暗能量场景中的演化。在有物质源的球对称背景下，场自相互作用的存在抑制了Vainshtein半径内第五种力的传播。我们估计了一个允许的参数空间，在这个参数空间中，模型可以与太阳系的约束相容，同时满足背景和扰动的宇宙学生存条件。
We propose a dark energy model where a scalar field $\ensuremath{\phi}$ has nonlinear self-interactions in the presence of a dilatonic coupling with the Ricci scalar. This belongs to a subclass of theories beyond Horndeski, which accommodates covariant Galileons and Brans-Dicke theories as specific cases. We derive conditions under which the scalar sound speed squared ${c}_{\mathrm{s}}^{2}$ is positive from the radiation era to today. Since ${c}_{\mathrm{s}}^{2}$ remains smaller than the order of 1, the deviation from Horndeski theories does not cause heavy oscillations of gauge-invariant gravitational potentials. In this case, the evolution of matter perturbations at low redshifts is similar to that in the coupled dark energy scenario with an enhanced gravitational interaction. On the spherically symmetric background with a matter source, the existence of field self-interactions suppresses the propagation of the fifth force inside a Vainshtein radius. We estimate an allowed parameter space in which the model can be compatible with Solar System constraints while satisfying conditions for the cosmological viability of background and perturbations.