  From the quasisymmetry-group perspective [Phys. Rev. Lett. 126, 120604
(2021)], we show the universal existence of collective, coherent modes of
excitations in many-body scar models in the degenerate limit, where the energy
spacing in the scar tower vanishes. The number of these modes, as well as the
quantum numbers carried by them, are given, not by the symmetry of the
Hamiltonian, but by the quasisymmetry of the scar tower: hence the name
quasi-Nambu-Goldstone modes. Based on this, we draw a concrete analogy between
the paradigm of spontaneous symmetry breaking and the many-body scar physics in
the degenerate limit.
