arXiv (Cornell University) · 2010 · 550 citations · 0 references
Natural SciencesPhysicsParticle PhysicsPlasma PhysicsTransport PhenomenaHigh-temperature PlasmasQuantum ChromodynamicsQuantum Field TheoryStrong InteractionTime-dependent TransportTransport PropertiesEffective Field Theories In Quantum ChromodynamicsFinite Temperature Quantum ChromodynamicsFluctuation-dissipation TheoremGluon DynamicsGreen-kubo FormalismHeavy Quark Effective TheoryPerturbative Quantum ChromodynamicsQuark-gluon Plasma Signatures
In the high‑temperature phase of QCD, the heavy‑quark momentum‑diffusion constant governs how rapidly a heavy quark kinetically equilibrates via a fluctuation‑dissipation relation. The study aims to compute Euclidean correlators of heavy quarks in the gluon plasma using lattice HQET. The authors compute Euclidean correlators on the lattice, extract the transport coefficient through a Kubo formula, and estimate the low‑frequency spectral contribution needed to reconcile perturbative predictions with the lattice data. The lattice data show a ~20 % increase in the Euclidean correlator at maximal time separation when cooling from 6Tc to 2Tc, a flattening that shifts spectral weight to lower frequencies, and overall agreement with next‑to‑leading‑order perturbation theory at the few‑percent level.
In the high-temperature phase of QCD, the heavy quark momentum diffusion constant determines, via a fluctuation-dissipation relation, how fast a heavy quark kinetically equilibrates. This transport coefficient can be extracted from thermal correlators via a Kubo formula. We present a lattice calculation of the relevant Euclidean correlators in the gluon plasma, based on a recent formulation of the problem in heavy-quark effective field theory (HQET). We find a $\approx20%$ enhancement of the Euclidean correlator at maximal time separation as the temperature is lowered from $6T_c$ to $2T_c$, pointing to stronger interactions at lower temperatures. At the same time, the correlator becomes flatter from $6T_c$ down to $2T_c$, indicating a relative shift of the spectral weight to lower frequencies. A recent next-to-leading order perturbative calculation of the correlator agrees with the time dependence of the lattice data at the few-percent level. We estimate how much additional contribution from the $\omega\lesssim T$ region of the perturbative spectral function would be required to bring it in agreement with the lattice data at $3.1T_c$.