标题： 在具有宇宙常数的标量-张量引力理论中选择共形框架 显示英文标题

标题： Choosing a conformal frame in scalar-tensor theories of gravity with a cosmological constant

摘要： 研究了带有附加宇宙学常数的布兰斯-迪克理论的宇宙学解，重点是选择一个共形框架以实现宇宙学常数衰减的场景，该场景具有不断增长的标量场。 我们特别关注乔丹框架，即具有非最小耦合的原始框架，以及没有非最小耦合的共形变换爱因斯坦框架。 对于渐近吸引子解以及“犹豫行为”，我们发现这些共形框架都不能作为分析原初核合成的基础。 作为补救措施，我们提出通过引入尺度不变的标量-物质耦合来修改原型BD理论，从而使爱因斯坦框架变得可接受。 由于非引力相互作用导致的量子异常效应，这种不变性被打破，自然地导致了第五种力，其特征是有限的作用范围和弱等效原理（WEP）的违反。 初步估计表明，理论预测大致与观测上限一致。 强烈鼓励进一步努力提高实验精度。 显示英文摘要

摘要： Cosmological solutions of the Brans-Dicke theory with an added cosmological constant are investigated with an emphasis to select a conformal frame in order to implement the scenario of a decaying cosmological constant, featuring an ever growing scalar field. We focus particularly on Jordan frame, the original frame with the nonminimal coupling, and conformally transformed Einstein frame without it. For the asymptotoic attractor solutions as well as the "hesitation behavior," we find that none of these conformal frames can be accepted as the basis of analyzing primordial nucleosynthesis. As a remedy, we propose to modify the prototype BD theory, by introducing a scale-invariant scalar-matter coupling, thus making Einstein frame acceptable. The invariacne is broken as a quantum anomaly effect due to the non-gravitational interactions, entailing naturally the fifth force, characterized by a finite force-range and WEP violation. A tentative estimate shows that the theoretical prediction is roughly consistent with the observational upper bounds. Further efforts to improve the experimental accuracy is strongly encouraged.