# The 35th International Symposium on Lattice Field Theory

18-24 June 2017
Palacio de Congresos
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# Contribution Parallel

Auditorio Manuel de Falla
Nonzero Temperature and Density

# Improved real-time dynamics from imaginary frequency lattice simulations

## Speakers

• Dr. Alexander ROTHKOPF

## Content

The computation of real-time properties, such as transport coefficients or bound state spectra of strongly interacting quantum fields in thermal equilibrium is a pressing matter. Since the sign problem prevents a direct evaluation of these quantities, lattice data needs to be analytically continued from the Euclidean domain of the simulation to Minkowski time, in general an ill-posed inverse problem.

Here we present a novel approach to improve the determination of real-time information in the form of spectral functions by setting up a simulation prescription in imaginary frequencies [1]. By carefully distinguishing between initial conditions and quantum dynamics one obtains access to correlation functions also outside the conventional Matsubara frequencies. In particular the range between w_0 and w_1=2\piT, which is most relevant for the inverse problem may be more highly resolved. In combination with the fact that in imaginary frequencies the Kernel of the inverse problem is not an exponential but only a rational function we observe significant improvements in the reconstruction of spectral functions, demonstrated in a simple 0+1 dimensional scalar field theory toy model.

[1] J.M. Pawlowski and A. Rothkopf, arXiv:1610.09531

## Preferred track (if multiple tracks have been selected)

Nonzero Temperature and Density