报告题目： Minimally modified gravity with auxiliary constraints

报告人：姚志邦 博士（中山大学）

报告时间：2023年05月05日（周五）下午15:30-16:30

报告地点：北洋园校区49教210室

报告摘要：

Modified gravity without arousing new degrees of freedom (DOF) is a kind of interesting gravitational theories which propagate only two tensorial DOF (TTDOF) like what happens in GR. Modified gravity theories with such a property are also called the "minimally modified gravity" (MMG). In order to systematically look for the MMG theories, we first investigate the possibility of reducing the number of DOF by introducing multiple auxiliary constraints (ACs) to a general Hamiltonian which is under the restriction of retaining spatial covariance as a gauge symmetry. Arbitrary numbers of scalar-, vector- and tensor-type ACs are considered a priori, yet we find that no vector- and tensor-type constraints should be introduced, and that scalar-type ACs should be no more than four for the purpose of constructing MMG theories. Through a detailed Hamiltonian analysis, then, we exhaust all the possible classifications of ACs and find out the corresponding minimalizing and symmetrizing conditions for obtaining the MMG theories. In particular, no condition is required in the case of four ACs, hence in this case the theory can couple with matter consistently and naturally. To illustrate our formalism, we build two concrete models with the use of the (generalised) Cayley-Hamilton theorem and derive the dispersion relations of the gravitational waves for each models, which are subject to the constraints from observations.

参考文献：

[1] Zhi-Bang Yao, Michele Oliosi, Xian Gao and Shinji Mukohyama, “Minimally modified gravity with auxiliary constraints formalism,” [arXiv:2302.02090 [gr-qc]].
[2]Zhi-Bang Yao, Michele Oliosi, Xian Gao and Shinji Mukohyama, “Minimally modified gravity with an auxiliary constraint: a Hamiltonian construction,” Phys. Rev. D 103, 023032 (2021) [arXiv:2011.00805 [gr-qc]].
[3] Xian Gao and Zhi-Bang Yao, “Spatially covariant gravity theories with two tensorial degrees of freedom: the formalism,” Phys. Rev. D 101, 064018 (2020) [arXiv:1910.13995 [gr-qc]].

报告人简介：

姚志邦，中山大学在读博士生，导师为高显教授。