TY  - GEN
AB  - 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.
AD  - Case Western Reserve University
AD  - University of Chicago
AD  - Ecole Polytechnique Fédérale de Lausanne
AU  - Hinterbichler, Kurt
AU  - Joyce, Austin
AU  - Mathys, Grégoire
DA  - 2024-10-01
ID  - 13612
JF  - Physical Review D
L1  - https://knowledge.uchicago.edu/record/13612/files/PhysRevD.110.085003.pdf
L2  - https://knowledge.uchicago.edu/record/13612/files/PhysRevD.110.085003.pdf
L4  - https://knowledge.uchicago.edu/record/13612/files/PhysRevD.110.085003.pdf
LA  - eng
LK  - https://knowledge.uchicago.edu/record/13612/files/PhysRevD.110.085003.pdf
N2  - 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.
PY  - 2024-10-01
T1  - Impossible symmetries and conformal gravity
TI  - Impossible symmetries and conformal gravity
UR  - https://knowledge.uchicago.edu/record/13612/files/PhysRevD.110.085003.pdf
Y1  - 2024-10-01
ER  -