Related papers: Pomeron with a Running Coupling Constant: Intercep…
The coefficient functions of the gluon condensate $<G^2>$, in the correlators of heavy-quark vector, axial, scalar and pseudoscalar currents, are obtained analytically, to two loops, for all values of $z=q^2/4m^2$. In the limiting cases…
We try to review the main current ideas and points of view on the running coupling constant in QCD. We begin by recalling briefly the classic analysis based on the Renormalization Group with some emphasis on the exact solutions of the RG…
On the occasion of the 70th birthday of Prof. Adriano Di Giacomo we report on recent numerical computations of the Landau gauge gluon and ghost propagators as well as of a non-symmetric MOM-scheme ghost-gluon vertex in quenched and full…
The determination of the Fermi coupling constant, G_F, is examined in the light of recently calculated 2-loop QED corrections and planned experiments to measure the muon lifetime to a level below 1ppm. The methods used in the calculation of…
The pomeron structure function is extracted from the latest H1 data and are subject to a QCD analysis. The result shows evidence for gluon recombination.
It is shown that the next-to-leading order (NLO) corrections to the QCD Pomeron intercept obtained from the BFKL equation, when evaluated in non-Abelian physical renormalization schemes with BLM optimal scale setting do not exhibit the…
The gluon spin coupling to a Gaussian correlated background gauge field induces an effective tachyonic gluon mass. It is momentum dependent and vanishes in the UV only like 1/p^2. In the IR, we obtain stabilization through a positive…
We address here the problem of describing both the total and the elastic proton-proton cross-section, through the four outstanding features of hadron scattering: (i) the optical point; (ii) the forward peak, (iii) the dip and (iv) the…
The gluon and quark condensates and their temperature dependence are investigated within QCD premises. The input for the former is a gauge invariant $gg$ kernel made up of the direct (D), exchange (X) and contact(C) QCD interactions in the…
We suggest a constrained instanton (CI) solution in the physical QCD vacuum which is described by large-scale vacuum field fluctuations. This solution decays exponentially at large distances. It is stable only if the interaction of the…
We compute the matching relation for the strong coupling constant within the framework of QCD up to four-loop order. This allows a consistent five-loop running (once the $\beta$ function is available to this order) taking into account…
We present a lattice QCD determination of the Mellin moments of the unpolarized gluon parton distribution function in the proton. The analysis is based on matrix elements of nonlocal gluon operators coupled to momentum-boosted proton…
The muLan experiment at the Paul Scherrer Institute will measure the lifetime of the positive muon with a precision of 1 ppm, giving a value for the Fermi coupling constant G_F at the level of 0.5 ppm. Meanwhile, by measuring the observed…
Calculations of deep inelastic processes (DIS) to next-to-next to leading order are discussed. Fitting $ep$ experiment in the range $2.5\leq Q^2\leq 230 GeV^2$, we find the coupling $\alpha_s(M_Z^2)=0.1163\pm0.0023$. We also get the gluon…
Starting from the running coupling in the gradient flow scheme, the QCD Lambda parameter $\Lambda_{\,\overline{\!\rm MS\!}\;}$ is determined analytically with respect to the reference scale $w_0$ in the pure gauge theory. A key element is…
Using the non-relativistic version of Borel sum rules, combined to the very accurate experimental information on the Charmonium and Upsilon spectra, we rigorously investigate the Euclidean mass of the Charm and Bottom quark. Our analysis is…
Sum rules for the nonperturbative piece of correlators (specifically, the vector current correlator) are discussed. The sum rule subtracting the perturbative part is of the superconvergent type. Thus it is dominated by the bound states and…
A novel extrapolation method has been used to deduce the charged Pion-Nucleon coupling constant from backward $np$ differential scattering cross sections. We applied it to new measurements performed at 162 MeV at the The Svedberg Laboratory…
Pure glue QCD is formulated on a 2+1 dimensional transverse lattice, using discrete light-front quantization. The transverse component of the gauge fields is taken to be compact, but in a linearized approximation with an effective…
Infrared features of gluon propagator, ghost propagator, QCD running coupling and the Kugo-Ojima parameter in lattice Landau gauge QCD are presented. The framework of PMS analysis suggests that there appear infrared, intermediate and…