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تسجيل مستخدم جديدSpectral representation of the shear viscosity for local scalar QFTs at finite temperature
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In local scalar quantum field theories (QFTs) at finite temperature correlation functions are known to satisfy certain non-perturbative constraints, which for two-point functions in particular implies the existence of a generalisation of the standard K{a}ll{e}n-Lehmann representation. In this work, we use these constraints in order to derive a spectral representation for the shear viscosity arising from the thermal asymptotic states, $eta_{0}$. As an example, we calculate $eta_{0}$ in $phi^{4}$ theory, establishing its leading behaviour in the small and large coupling regimes.
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