arXiv subjects

O. Azi

Publications and source records attributed to O. Azi.

4 recordsLinked to original sources

arXiv2004

Infrared Behavior of High-Temperature QCD

The damping rate γ_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 γ_t(0) and γ_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.

hep-ph↗

arXiv1999

An infrared singularity in the damping rate for longitudinal gluons in hot QCD

We calculate $γ_l(0)$, the damping rate for longitudinal on-shell gluons with zero momentum in hot QCD using the hard-thermal-loop (htl) scheme. We find it to be divergent in the infrared, which means that in this scheme $γ_l(0)$ is different from $γ_t(0)$, the corresponding damping rate for transverse gluons which is known to be finite. This result suggests that the htl scheme is infrared sensitive and thus may need to be improved upon in this sector. We discuss this issue after we present our calculation.

hep-ph↗

arXiv1997

A potential infrared problem with the damping rates for gluons with soft momentum in hot QCD

We calculate the damping rate $γ_l$ for longitudinal gluons with zero momentum in finite high temperature QCD and show that some of its contributing terms are infrared divergent. This is in contrast with the expectation that this damping rate is to be equal to the corresponding one $γ_t$ for transverse gluons which is known to be finite. Our calculation was motivated by the fact that similar divergent terms occur when we calculated in a previous work $γ_t$ to order $ p^2$, p being the momentum of the gluon. After we present our results, we briefly discuss them.

hep-ph↗

arXiv1997

Damping rate for transverse gluons with finite soft momentum in hot QCD

We calculate the damping rate for transverse gluons with {\nineti finite} soft momentum to leading order in perturbative hot QCD. The internal momenta of the one-loop contributing diagrams are soft. This means we have to use effective vertices and propagators which incorporate the so-called hard thermal loops. We expand the damping rate in powers of the incoming momentum and argue that the series ought to converge within a finite radius of convergence. We contrast such a behavior with the one obtained from a previous calculation that produced a logarithmic behavior, a calculation based on letting the gluon momentum come from the hard limit down towards the interior of the soft region. This difference in behavior may point to interesting physics around some `critical' region.

hep-ph↗