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.