Bimetric theory describes a massless and a massive spin-2 field with fully non-linear (self-)interactions. It has a rich phenomenology and has been successfully tested with several data sets. However, the observational constraints have not been combined in a consistent framework, yet. We propose a parametrization of bimetric solutions in terms of the effective cosmological constant $\Lambda$ and the mass $m_\mathrm{FP}$ of the spin-2 field as well as its coupling strength to ordinary matter $\bar\alpha$. This simplifies choosing priors in statistical analysis and allows to directly constrain these parameters with observational data not only from local systems but also from cosmology. By identifying the physical vacuum of bimetric theory these parameters are uniquely determined. We work out the dictionary for the new parametrization for various submodels and present the implied consistency constraints on the physical parameter space. We then apply the dictionary to derive observational constraints from SN1a on the physical parameters. As a result we find that even self-accelerating models with a heavy spin-2 field are in perfect agreement with current supernova data.

中文翻译：

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双度量理论的物理参数空间和SN1a约束

双计量理论描述了具有完全非线性（自）相互作用的无质量和有质量的自旋 2 场。它具有丰富的现象学，并已成功通过多个数据集进行测试。然而，观察约束尚未结合在一个一致的框架中。我们根据自旋 2 场的有效宇宙学常数 $\Lambda$ 和质量 $m_\mathrm{FP}$ 以及它与普通物质的耦合强度 $\bar\alpha$ 提出了双度量解的参数化. 这简化了统计分析中先验的选择，并允许使用不仅来自本地系统而且来自宇宙学的观测数据直接约束这些参数。通过识别双度量理论的物理真空，这些参数是唯一确定的。我们为各种子模型制定了新参数化的字典，并提出了对物理参数空间的隐含一致性约束。然后我们应用字典从 SN1a 中导出对物理参数的观察约束。结果我们发现，即使是具有重自旋 2 场的自加速模型也与当前的超新星数据完全一致。