论文标题
脾气良好的宇宙常数:Horndeski变化
The Well-Tempered Cosmological Constant: The Horndeski Variations
论文作者
论文摘要
恢复是解决原始宇宙学恒定问题的少数经典野外理论方法之一,动态地取消了大型(可能是普朗克量表)真空能量,并完整地使物质成分完整,同时提供了具有较晚时间宇宙加速的可行宇宙学和最终的界限。我们提出了一般的约束,即具有不同术语组合的Horndeski重力模型的变化必须满足,以便接受一个确切的Sitter时空,该时空无法响应任意较大的宇宙学常数。我们明确地得出了几种良好的降温标量模型,并可以提供标准的宇宙历史记录,包括当前的宇宙加速度。考虑了稳定标准,de Sitter状态的吸引者行为以及模型对无压力物质的响应。脾气暴躁的条件可用于专注于具有特殊兴趣的特定重力模型 - 不仅可以消除原始的宇宙恒定问题,而且可以提供自由Horndeski函数之间的关系并将其减少到几个参数,适合测试重力和宇宙学数据分析。
Well tempering is one of the few classical field theory methods for solving the original cosmological constant problem, dynamically canceling a large (possibly Planck scale) vacuum energy and leaving the matter component intact, while providing a viable cosmology with late time cosmic acceleration and an end de Sitter state. We present the general constraints that variations of Horndeski gravity models with different combinations of terms must satisfy to admit an exact de Sitter spacetime that does not respond to an arbitrarily large cosmological constant. We explicitly derive several specific scalar-tensor models that well temper and can deliver a standard cosmic history including current cosmic acceleration. Stability criteria, attractor behavior of the de Sitter state, and the response of the models to pressureless matter are considered. The well tempered conditions can be used to focus on particular models of modified gravity that have special interest -- not only removing the original cosmological constant problem but providing relations between the free Horndeski functions and reducing them to a couple of parameters, suitable for testing gravity and cosmological data analysis.