Abstract
We study the spectral representation of finite temperature, out of time ordered (OTO) correlators on the multi-time-fold generalised Schwinger-Keldysh contour. We write the contour-ordered correlators as a sum over time-order permutations acting on a fundamental array of Wightman correlators. We decompose this Wightman array in a basis of column vectors, which provide a natural generalisation of the familiar retarded-advanced basis in the finite temperature Schwinger-Keldysh formalism. The coefficients of this decomposition take the form of generalised spectral functions, which are Fourier transforms of nested and double commutators. Our construction extends a variety of classical results on spectral functions in the SK formalism at finite temperature to the OTO case.
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Chaudhuri, S., Chowdhury, C. & Loganayagam, R. Spectral representation of thermal OTO correlators. J. High Energ. Phys. 2019, 18 (2019). https://doi.org/10.1007/JHEP02(2019)018
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DOI: https://doi.org/10.1007/JHEP02(2019)018