@article{TEXTUAL,
      recid = {13612},
      author = {Hinterbichler, Kurt and Joyce, Austin and Mathys,  Grégoire},
      title = {Impossible symmetries and conformal gravity},
      journal = {Physical Review D},
      address = {2024-10-01},
      number = {TEXTUAL},
      abstract = {We explore the physics of relativistic gapless phases  defined by a mixed anomaly between two generalized  conserved currents. The gapless modes can be understood as  Goldstone modes arising from the nonlinear realization of  (generically higher-form) symmetries arising from these  currents. In some cases, the anomaly cannot be reproduced  by any local and unitary theory, indicating that the  corresponding symmetries are impossible, in the sense that  they cannot appear in a Lorentzian physical system. We give  a general construction and illustrate it with several  examples. Most notably, we study conformal gravity from  this perspective, describing the higher-form symmetries of  the linear theory and showing how it can be understood in  terms of anomalies. Along the way we clarify some aspects  of electric-magnetic duality in linear conformal gravity.},
      url = {http://knowledge.uchicago.edu/record/13612},
}