京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18793号 / 理博第4051号 / 新制||理||1583(附属図書館) / 31744 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 田中 貴浩, 教授 中村 卓史, 教授 高柳 匡 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

In this thesis a set of recently proposed multigravity theories is analysed. In the special case of bimetric gravity, the theory has been conclusively shown to be ghost-free. On the other hand, for multigravity theories in general, the ghost-issue has not been settled conclusively. Motivated by this fact, the main object of this thesis is to clarify what has been proven so far and what issues that still needs to be addressed. We also provide new calculations and results pointing in the direction that the multigravity theories must be restricted to a set of bimetric Hassan-Rosen couplings in a tree-type structure in order to be consistent. In particular, we prove that for a multivielbein theory of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cmathscr%7BN%7D" /> interacting vielbeins, the Lorentz equations of motion is a set of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?(%5Cmathscr%7BN%7D-1)" /> Deser-van Nieuwenhuizen conditions if and only if the theory consists of bimetric Hassan-Rosen couplings in a tree-type structure.