标题： 宇宙加速有界与无界 显示英文标题

标题： Cosmic Acceleration with and without Limits

摘要： 一类新颖且有趣的标量-张量引力理论是具有场运动限制的理论，其中标量场要么趋于恒定加速度，要么停止加速并趋于恒定速度。 我们将这些理论与动态抵消高能宇宙常数的能力相结合，例如通过良好调节或自调优方法。 尽管存在大尺度的宇宙常数，人们仍可以成功地拥有一个以物质主导时期和晚期加速为特征的宇宙膨胀历史，虽然晚期的 de Sitter 极限可能不稳定。 诸如 Dirac-Born-Infeld 动作中的极点模型，对于宇宙速度极限特别有趣。 显示英文摘要

摘要： A novel, interesting class of scalar-tensor gravity theories is those with a limit on the field motion, where the scalar field either goes to a constant acceleration or stops accelerating and goes to a constant velocity. We combine these with the ability to dynamically cancel a high energy cosmological constant, e.g. through the well tempered or self tuning approaches. One can successfully have a cosmic expansion history with a matter dominated epoch and late time acceleration despite a large cosmological constant, although the late time de Sitter limit may be unstable. Pole models, such as in a Dirac-Born-Infeld action, are of particular interest for a cosmic speed limit.