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Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 5: Theorie I

HK 5.11: Talk

Monday, March 17, 2003, 19:00–19:15, D

Asymptotic Freedom at High Temperatures — •Roland A. Schneider — Physik-Department, Technische Universität München, Garching, Germany; ECT*, Trento, Italy

We calculate the screening of the static potential between two charges in (non)abelian gauge theories at high temperatures. Instead of a loop expansion of a gauge boson self-energy, we evaluate the energy shift of the vacuum to order e2 after applying an external static magnetic field and extract a temperature- and momentum-dependent dielectric permittivity. The Hard Thermal Loop gluon and photon Debye masses are recovered from the lowest lying Landau levels of the perturbed vacuum. The thermal imaginary part of the energy shift becomes temperature-independent and exactly cancels the well-known zero temperature imaginary part, thus rendering the vacuum stable. Including the T=0 contributions, a field-independent coupling αs(T) is obtained. It can be interpreted as the ordinary zero temperature running coupling constant with average thermal momenta ⟨ k ⟩ ≈ 2 π T for gluons and ⟨ k ⟩ ≈ π T for quarks, implying asymptotic freedom at high temperatures and large distances.
Work supported in part by BMBF and GSI.

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