The tension between measurements of the Hubble constant obtained at different redshifts may provide a hint of new physics active in the relatively early universe, around the epoch of matter-radiation equality. A leading paradigm to resolve the tension is a period of early dark energy, in which a scalar field contributes a subdominant part of the energy budget of the universe at this time. This scenario faces significant fine-tuning problems which can be ameliorated by a non-trivial coupling of the scalar to the standard model neutrinos. These become non-relativistic close to the time of matter-radiation equality, resulting in an energy injection into the scalar that kick-starts the early dark energy phase, explaining its coincidence with this seemingly unrelated epoch. We present a minimal version of this neutrino-assisted early dark energy model, and perform a detailed analysis of its predictions and theoretical constraints. We consider both particle physics constraints — that the model constitute a well-behaved effective field theory for which the quantum corrections are under control, so that the relevant predictions are within its regime of validity — and the constraints provided by requiring a consistent cosmological evolution from early through to late times. Our work paves the way for testing this scenario using cosmological datasets.

在不同红移下获得的哈勃常数测量值之间的张力可能提供了在相对早期的宇宙中活跃的新物理学的暗示，围绕着物质辐射相等的时代。解决紧张局势的主要范式是早期暗能量时期，其中标量场在此时贡献了宇宙能量收支的次要部分。这种情况面临重大的微调问题，可以通过标量与标准模型中微子的非平凡耦合来改善。这些在接近物质辐射相等的时候变得非相对论，导致能量注入标量，启动早期的暗能量阶段，解释了它与这个看似无关的时代的巧合。我们展示了这个中微子辅助的早期暗能量模型的最小版本，并对其预测和理论约束进行详细分析。我们考虑了粒子物理学的约束——模型构成了一个行为良好的有效场论，量子校正受到控制，因此相关预测在其有效性范围内——以及通过要求一致的宇宙学演化提供的约束。早到晚。我们的工作为使用宇宙学数据集测试这一场景铺平了道路。以便相关预测在其有效性范围内——以及由需要从早期到晚期一致的宇宙学演化所提供的约束。我们的工作为使用宇宙学数据集测试这一场景铺平了道路。以便相关预测在其有效性范围内——以及由需要从早期到晚期一致的宇宙学演化所提供的约束。我们的工作为使用宇宙学数据集测试这一场景铺平了道路。