4 research outputs found
Damping of very soft moving quarks in high-temperature QCD
We determine the analytic expression of the damping rates for very soft
moving quarks in an expansion to second order in powers of their momentum in
the context of QCD at high temperature. The calculation is performed using the
hard-thermal-loop-summed perturbation scheme. We describe the range of validity
of the expansion and make a comparison with other calculations, particularly
those using a magnetic mass as a shield from infrared sensitivity. We discuss
the possible occurrence of infrared divergences in our results and argue that
they are due to magnetic sensitivity.Comment: 24 pages, REVTe
Ultrasoft Quark Damping in Hot QCD
We determine the quark damping rates in the context of next-to-leading order
hard-thermal-loop summed perturbation of high-temperature QCD where weak
coupling is assumed. The quarks are ultrasoft. Three types of divergent
behavior are encountered: infrared, light-cone and at specific points
determined by the gluon energies. The infrared divergence persists and is
logarithmic whereas the two others are circumvented.Comment: 16 page
Infrared Behavior of High-Temperature QCD
The damping rate \gamma_t(p) of on-shell transverse gluons with ultrasoft
momentum p is calculated in the context of next-to-leading-order
hard-thermal-loop-summed perturbation of high-temperature QCD. It is obtained
in an expansion to second order in p. The first coefficient is recovered but
that of order p^2 is found divergent in the infrared. Divergences from
light-like momenta do also occur but are circumvented. Our result and method
are critically discussed, particularly regarding a Ward identity obtained in
the literature. When enforcing the equality between \gamma_t(0) and
\gamma_l(0), a rough estimate of the magnetic mass is obtained. Carrying a
similar calculation in the context of scalar quantum electrodynamics shows that
the early ultrasoft-momentum expansion we make has little to do with the
infrared sensitivity of the result.Comment: REVTEX4, 55 page