Chiral restoration effects on the shear viscosity of a pion gas
| Autor: | Heckmann, Klaus, Buballa, Michael, Wambach, Jochen |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | Eur. Phys. J. A (2012) 48: 142 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1140/epja/i2012-12142-2 |
| Popis: | We investigate the shear viscosity of a pion gas in relativistic kinetic theory, using the Nambu-Jona-Lasinio model to construct the pion mass and the pi-pi interaction at finite temperature. Whereas at low temperatures the scattering properties and, hence, the viscosity are in agreement with lowest-order chiral perturbation theory, we find strong medium modifications in the crossover region. Here the system is strongly coupled and the scattering lengths diverge, similarly as for ultra-cold Fermi gases at a Feshbach resonance. As a consequence, the ratio eta/s is found to be strongly reduced as compared to calculations without medium-modified masses and scattering amplitudes. However, the quantitative results are very sensitive to the details of the applied approximations. Comment: 15 pages, 12 figures; v2: extended discussions of the dressed sigma propagator and the low-temperature limit, typos corrected, accepted version |
| Databáze: | arXiv |
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