Spontaneous Lorentz and diffeomorphism violation, massive modes, and gravity

  title={Spontaneous Lorentz and diffeomorphism violation, massive modes, and gravity},
  author={Robert Bluhm and Shu Hong Fung and Alan Kosteleck{\'y}},
  journal={Physical Review D},
Theories with spontaneous local Lorentz and diffeomorphism violation contain massless NambuGoldstone modes, which arise as field excitations in the minimum of the symmetry-breaking potential. If the shape of the potential also allows excitations above the minimum, then an alternative gravitational Higgs mechanism can occur in which massive modes involving the metric appear. The origin and basic properties of the massive modes are addressed in the general context involving an arbitrary tensor… 

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