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arXiv · 1412.2554

In-medium Spectral Functions in a Coarse-Graining Approach

Stephan Endres·Hendrik van Hees·Janus Weil·Marcus Bleicher
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Abstract

We use a coarse-graining approach to extract local thermodynamic properties from simulations with a microscopic transport model by averaging over a large ensemble of events. Setting up a grid of small space-time cells and going into each cell's rest frame allows to determine baryon and energy density. With help of an equation of state we get the corresponding temperature $T$ and baryon-chemical potential $\mu_{\mathrm{B}}$. These results are used for the calculation of the thermal dilepton yield. We apply and compare two different spectral functions for the $\rho$ meson, firstly a calculation from hadronic many-body theory and secondly a calculation from experimental scattering amplitudes. The results obtained with our approach are compared to measurements of the NA60 Collaboration. A relatively good description of the data is achieved with both spectral functions. However, the hadronic many-body calculation is found to be closer to the experimental data with regard to the in-medium broadening of the spectral shape.

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Stephan Endres, Hendrik van Hees, Janus Weil, Marcus Bleicher. 2014-12-08. In-medium Spectral Functions in a Coarse-Graining Approach. https://doi.org/10.1088/1742-6596%2F599%2F1%2F012020

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