Vector mesons show up in the electromagnetic current-current correlator. QCD sum rules provide a constraint on hadronic models for this correlator. This constraint is discussed for the case of finite nuclear density concerning the longitudinal as well as the transverse part of the current-current correlator at finite three-momentum. PACS numbers: 24.85.+p, 21.65.+f, 12.38.Lg, 14.40.Cs

Three-loop QCD corrections to the vector current correlator are considered. The large momentum procedure is applied in order to evaluate mass corrections up to order (m2/q2)6. The inclusion of the first seven terms to the ratio R = σ(e+e− → hadrons)/σ(e+e− → μ+μ−) leads to reliable predictions from the high energy region down to relatively close to threshold. PACS numbers: 12.38.-t, 12.38.Bx, 1...

Abstract We study the diffusion of heavy quarks in the Quark Gluon Plasma using the Langevin equations of motion and estimate the contribution of the transport peak to the Euclidean current-current correlator. We show that the Euclidean correlator is remarkably insensitive to the heavy quark diffusion coefficient and give a simple physical interpretation of this result using the free streaming ...

We present analytical next-to-leading order results for the correlator of baryonic currents at the three loop level with one finite mass quark. We obtain the massless and the HQET limit of the correlator from the general formula as particular cases. We also give explicit expressions for the moments of the spectral density. Baryons are an important source of information on QCD interactions. Mass...

An update is described of a model independent method to determine the hadronic contribution QED running coupling at Zboson mass scale, ∆αHAD(M2 Z ). The major source uncertainty from light quark vector current correlator zero momentum. This substantially reduced using recently improved lattice QCD results for this correlator. result ) = 274.13(0.73) × 10−4

The forms of the neutral, non-strange pseudoscalar propagator matrix and mixed axial current correlator, 〈0|T (AμAν)|0〉, are discussed at next-toleading (one-loop) order in chiral perturbation theory, and the results compared to those obtained using QCD sum rules. This comparison provides a check of the truncations employed in the sum rule treatment of the current correlator. Values for the slo...