Abstract
In this paper we return to the question of the modular properties of a generalised Gibbs ensemble of a single free fermion. We extend our previous proposals to a GGE containing an arbitrary number of conserved charges and provide a physical interpretation of the result in terms of a line defect. The defect description perfectly explains the product formula for the modular transformation we found previously. We also give a proposal for a Hamiltonian approach to the line defect.
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Acknowledgments
We would like to thank A. Dymarksy, N. Gromov, S. Murthy, A. Sfondrini, R. Tateo and D. Zagier for discussions. This work was supported by the EPSRC grant EP/V520019/1.
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ArXiv ePrint: 2311.04564
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Downing, M., Watts, G.M.T. Free fermions, KdV charges, generalised Gibbs ensembles, modular transforms and line defects. J. High Energ. Phys. 2024, 41 (2024). https://doi.org/10.1007/JHEP01(2024)041
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DOI: https://doi.org/10.1007/JHEP01(2024)041