论文标题
哈密顿形式主义中非模样重力的量规对称性
Gauge symmetry of unimodular gravity in Hamiltonian formalism
论文作者
论文摘要
我们确定了受约束的哈密顿形式主义中单模型重力的量规对称性的描述。特别是，我们证明了如何限制从哈密顿约束代数出现的差异参数的横向条件。替代形式长期以来称为通过无限制的两种形式而不是横向矢量场来参数保留体积的差异。该规格对称性可还原。我们研究了这种形式的单模型重力（UG）对称形式的描述。 Becchi-rouet-stora-tyutin-巴塔尔·弗拉德金 - 维尔科维斯基（BFV-BRST）汉密尔顿形式主义是针对两种形式的UG仪表对称性的。这两个BR的复合体具有微妙的不等值：它们的BRST共同体组不是同构。特别是，对于与限制量规参数相关的第一个复合物，宇宙常数与任何非平凡的BRST Cocycle不符，而对于替代复合物而言。在物理学的措辞中，这意味着$λ$是由场渐近学定义的固定参数，而不是从第一个复合物的角度观察到的物理观察。第二种形式主义将$λ$视为可观察的，具有无限制的初始数据。
We work out the description of the gauge symmetry of unimodular gravity in the constrained Hamiltonian formalism. In particular, we demonstrate how the transversality conditions restricting the diffeomorphism parameters emerge from the algebra of the Hamiltonian constraints. The alternative form is long known as parametrizing the volume preserving diffeomorphisms by unrestricted two-forms instead of the transverse vector fields. This gauge symmetry is reducible. We work out the Hamiltonian description of this form of unimodular gravity (UG) gauge symmetry. Becchi-Rouet-Stora-Tyutin--Batalin-Fradkin-Vilkovisky (BFV-BRST) Hamiltonian formalism is constructed for both forms of the UG gauge symmetry. These two BRST complexes have a subtle inequivalence: Their BRST cohomology groups are not isomorphic. In particular, for the first complex, which is related to the restricted gauge parameters, the cosmological constant does not correspond to any nontrivial BRST cocycle, while for the alternative complex it does. In the wording of physics, this means $Λ$ is a fixed parameter defined by the field asymptotics rather than the physical observable from the standpoint of the first complex. The second formalism views $Λ$ as the observable with unrestricted initial data.
