We explore a new action formulation of hyperfluids, fluids with intrinsic hypermomentum. Brown's Lagrangian for a relativistic perfect fluid is generalised by incorporating the degrees of freedom encoded in the hypermomentum tensor, namely by including connection-matter couplings. Quite interestingly, generic hyperfluids are imperfect, since hypermomentum induces such effects as bulk and shear viscosities as well as heat fluxes. The various coefficients that appear in the first order expansion of hydrodynamics can now be deduced from a Lagrangian formulation, given a geometrical interpretation and a suggested microscopic description in terms of hypermomentum. This connection between hypermomentum and dissipative fluids could shed new light on the physics of relativistic hydrodynamics. The applicability of the new formalism is demonstrated by exact cosmological solutions.

中文翻译：

---

超流体动力学：来自超动量的相对论粘性流体

我们探索一种新的超流体作用配方，即具有内在超动量的流体。相对论完美流体的布朗拉格朗日量通过合并超动量张量中编码的自由度进行推广，即通过包含连接物质耦合。非常有趣的是，一般的超流体是不完美的，因为超动量会引起体积粘度、剪切粘度以及热通量等效应。给出几何解释和建议的超动量微观描述，现在可以从拉格朗日公式推导出流体动力学一阶展开中出现的各种系数。超动量和耗散流体之间的这种联系可以为相对论流体动力学的物理学提供新的线索。新形式主义的适用性通过精确的宇宙学解决方案得到了证明。