We present skeleton-motivated evaluation of QCD observables. The approach can be applied in analytic versions of QCD in certain classes of renormalization schemes. We present two versions of analytic QCD which can be regarded as low-energy modifications of the “minimal” analytic QCD and which reproduce the measured value of the semihadronic τ decay ratio rτ . Further, we describe an approach of...

The lattice QCD studies indicate that the critical temperature Tc ≃ 260 − 280 MeV of the deconfinement phase transition in quenched QCD is considerably smaller than the lowest-lying glueball mass mG ≃ 1500 − 1700 MeV, i.e., Tc ≪ mG. As a consequence of this large difference, the thermal excitation of the glueball in the confinement phase is strongly suppressed by the statistical factor as eGc ≃...

Using recent measurements of the b-quark fragmentation distribution obtained in e+e− → bb events registered at the Z pole, the non-perturbative QCD component of the distribution has been extracted independently of any hadronic physics modelling. This distribution depends only on the way the perturbative QCD component has been defined. When the perturbative QCD component is taken from a parton s...

Using recent measurements of the b-quark fragmentation distribution obtained in e+e− → bb events registered at the Z pole, the non-perturbative QCD component of the distribution has been extracted independently of any hadronic physics modelling. This distribution depends only on the way the perturbative QCD component has been defined. When the perturbative QCD component is taken from a parton s...

We describe our methods for performing quantum chromodynamics (QCD) simulations that sustain up to 20% of the peak performance on BlueGene supercomputers. We present our methods, scaling properties, and first cutting edge results relevant to QCD. We show how this enables unprecedented computational scale that brings lattice QCD to the next generation of calculations. We present our QCD simulati...

The Perturbative QCD Potential and the t ¯ t Threshold Abstract We include the full second-order corrections to the static QCD potential in the analysis of the t ¯ t threshold cross section. There is an unexpectedly large difference between the QCD potential improved by the renormalization-group equation in momentum space and the potential improved by the renormalization-group equation in coord...

We discuss QCD in the Hamiltonian frame work. We treat finite density QCD in the strong coupling regime. We present a parton-model inspired regularisation scheme to treat the spectrum (θ-angles) and distribution functions in QED 1+1. We suggest a Monte Carlo method to construct low-dimensionasl effective Hamiltonians. Finally, we discuss improvement in Hamiltonian QCD. 1. Introduction There are...

We review the calculation of moments of both the polarized and unpolarized parton distribution functions of the nucleon in lattice QCD, and in particular their extrapolation to the physical region. We also discuss the reconstruction of the x dependence of the valence quark distributions in the nucleon from a finite number of lattice moments.

We study Λ QCD /m B corrections to factorization in B → Kπ decays. First, we analyze these decay channels within factorization, showing that, irrespectively of the value of γ, it is not possible to reproduce the experimental data. Then, we discuss Λ QCD /m B corrections to these processes, and argue that there is a class of doubly Cabibbo enhanced non-factorizable contributions, usually called ...

I review recent Lattice results. In particular, the confinement mechanism and string breaking, glueballs and hybrid mesons as well as light hadron spectroscopy are discussed.