Ostrogradsky mode in scalar-tensor theories with higher-order derivative couplings to matter

被引：12

作者：

Naruko, Atsushi ^{[1
]}

Saito, Ryo ^{[2
,3
]}

Tanahashi, Norihiro ^{[4
]}

Yamauchi, Daisuke ^{[5
]}

机构：

[1] Kyoto Univ, Yukawa Inst Theoret Phys, Ctr Gravitat Phys & Quantum Informat, Kyoto 6068502, Japan

[2] Yamaguchi Univ, Grad Sch Sci & Engn, Yamaguchi 7538512, Japan

[3] Univ Tokyo, Kavli Inst Phys & Math Universe Kavli IPMU, Todai Inst Adv Study, WPI, Chiba 2778583, Japan

[4] Chuo Univ, Dept Phys, Bunkyo Ku, Kasuga, Tokyo 1128551, Japan

[5] Kanagawa Univ, Fac Engn, Yokohama, Kanagawa 2218686, Japan

来源：

PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS | 2023年 / 2023卷 / 05期

关键词：

COSMOLOGICAL PERTURBATIONS; DISFORMAL INVARIANCE; TRANSFORMATIONS; HORNDESKI;

D O I：

10.1093/ptep/ptad049

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Metric transformation is a tool to find a new theory of gravity beyond general relativity. The gravity action is guaranteed to be free from the dangerous Ostrogradsky mode as long as the metric transformation is regular and invertible. Various degenerate higher-order scalar-tensor theories without extra degrees of freedom have been found through the metric transformation with a scalar field and its derivatives. In this work, we examine how a matter coupling changes the degeneracy for a theory generated from the Horndeski theory through the metric transformation with the second derivative of a scalar field, taking a minimally coupled free scalar field as the matter field. When the transformation is invertible, this theory is equivalent to the Horndeski theory with a higher-order derivative coupling to the matter scalar field. Working in this Horndeski frame and the unitary gauge, we find that the degeneracy conditions are solvable and the matter metric must have a certain structure to remove the Ostrogradsky mode.

引用

页数：21