# BMS對稱陪集 – 重力子作為南-戈玻色子的一種

Seminar:- Coset for BMS: Graviton as a Nambu-Goldstone Boson

It has been known that graviton can be thought of as a Nambu-Goldstone (NG) boson for spontaneously broken GL(4) symmetry, which is a part of large gauge transformations associated to general covariance. In this interpretation, all the components of the metric are identified with NG bosons, so that these NG modes include gauge degrees of freedom in addition to the two physical helicity modes of graviton. In this talk, the speaker will revisit such property of graviton based on the Bondi-Metzner-Sachs (BMS) symmetry, an infinite dimensional symmetry of asymptotically flat spacetimes. In particular, he will illustrate that the viewpoint of asympotics resolves the mismatch between the number of broken symmetries and physical helicity modes.

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