Related papers: UV contribution and power dependence on $\Lambda_\…
The proton-polarizability contribution to the muonic-hydrogen Lamb shift is a major source of theoretical uncertainty in the extraction of the proton charge radius. An empirical evaluation of this effect, based on the proton structure…
A simple model for the hadronic contribution to the photon vacuum polarization function $\Pi_{had}(q^2)$, for spacelike momenta, is presented. For small momenta, the two loop contribution from the pseudoscalar meson octet is computed from…
We describe the Adler function in Quantum Chromodynamics using a transseries representation within a resurgent framework. The approach is based on a Borel-Ecalle resummation of the infrared renormalons combined with an effective running for…
Elements of the alternative approach to hard collisions of photons, proposed recently by the author, are reviewed, with particular attention to QCD analysis of $F^{\gamma}_2$. This approach is based on clear separation of genuine QCD…
We investigate the impact parameter dependent parton distributions for a relativistic composite system in light-front framework. We express them in terms of overlaps of light-cone wave functions for a self consistent two-body spin-1/2…
We calculate the isoscalar axial-vector coupling constants of the Lambda hyperon using the method of QCD sum rules. A determination of these coupling constants reveals the individual contributions of the u, d and the s quarks to the spin…
We study the transverse momentum dependence of the Landau-Pomeranchuk-Migdal effect in QED, starting from the high energy expansion of the solution of the Dirac equation in the presence of an external field. The angular integrated energy…
Demanding the analyticity of hadronic observables (calculated in terms of power series of the running coupling) as a {\it whole}, we show that they are free of the Landau singularity. Employing resummation and dispersion-relation…
This talk brings attention to what is knowable from perturbative QCD theory on two-parton distribution functions in the light of CDF measuruments of the inclusive cross section for double parton scattering.
We establish a relation between the two-point field strength correlator in QCD and the dual field propagator of the effective dual Abelian Higgs model describing the infrared behaviour of QCD.
We have calculated the next-to-leading order perturbative QCD corrections to the photon energy spectrum in radiative Upsilon decays. The higher-order corrections significantly modify the shape of the spectrum, in particular at large photon…
We discuss a method for calculating the heavy quark vacuum polarisation contribution to the muon anomalous magnetic moment, $a_\mu$, using perturbative QCD. This approach is independent of $e^+e^-$ cross-section data allowing a fully…
We discuss our present knowledge of $\alpha_s$, the fundamental running coupling or effective charge of Quantum Chromodynamics (QCD). A precise understanding of the running of $\alpha_s(Q^2) $ at high momentum transfer, $Q$, is necessary…
We summarize the current status of our understanding of the structure of the perturbative QCD expressions for the QCD generalization of the Crewther relation.
We calculate and resum a perturbative expansion of nuclear enhanced power corrections to the structure functions measured in deeply inelastic scattering of leptons on a nuclear target. Our results for the Bjorken $x$-, $Q^2$- and…
Sufficiently inclusive observables in the decay of the tau lepton can be calculated using the methods of perturbative QCD. These include the asymmetry parameter $A_\tau$ that determines that angular distribution of the total hadron momentum…
We elaborate on the relation between perturbative and power-like corrections to short-distance sensitive QCD observables. We confront theoretical expectations with explicit perturbative calculations existing in literature. As is expected,…
The normalization of the gluon condensate and of renormalon-related power corrections in QCD is computed under the assumption that their ``perturbative'' part dominates over any eventual extra contribution from the non-trivial vacuum. The…
We calculate the low energy contribution to quarkonium correlators in Euclidean time in lattice QCD. This contribution was found to give the dominant source of the temperature dependence of the correlators. We have found that the low energy…
We apply analytic perturbation theory to the QCD analysis of the xF_3 structure function data of the CCFR collaboration. We use different approaches for the leading order Q^2 evolution of the xF_3 structure function and compare the…