Speaker
Description
Measurements of real-time spectral functions (such as e.g. electric AC conductivity) in lattice gauge theory simulations usually rely on a numerically ill-defined analytic continuation of lattice correlation functions from imaginary (Euclidean) to real (Minkowski) frequencies. With only Euclidean correlators as input, this procedure has fundamentally limited frequency resolution of order of pi*T. On the other hand, at sufficiently high temperatures gauge fields become almost classical and practically do not depend on Euclidean time, effectively reducing to three-dimensional static fields. We demonstrate that at sufficiently high temperatures, finite-temperature dimensional reduction allows to extract much more information on fermionic spectral functions from Euclidean-time Monte-Carlo simulations. With a good precision, spectral functions can be calculated for a single fermion moving in the background of static, disordered gauge fields, which is a polynomial-complexity problem. We first test this approach in 1+1-dimensional U(1) lattice gauge theory with dynamical fermions and demonstrate excellent agreement with spectral functions calculated from exact diagonalisation of the full quantum Hamiltonian. We then demonstrate that dimensional reduction also works well for Euclidean-time meson correlators in high-temperature lattice QCD.
| Parallel Session (for talks only) | QCD at nonzero temperature and density |
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