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A general strategy to solve the non-perturbative renormalization problem in lattice QCD, using finite-size techniques and numerical simulations, is described. As an illustration we discuss the computation of the axial current normalization constant, the running coupling at zero quark masses and the scale evolution of the renormalized axial density. The non-perturbative calculation of O(a) correction terms (as they appear in Symanzik's improvement programme) is another important field of application., 14 pages, uuencoded gzipped postscript file

10 pp. (1995)., We reconsider the prediction of the semileptonic branching ratio of B mesons, using the recent calculation [E. Bagan et al., Nucl. Phys. B 432 (1994) 3] of the radiative corrections with account for finite quark masses in nonleptonic decays and taking into account corrections. For the semileptonic branching ratio we obtain Bsl = (11.8 ± 1.6)% using pole quark masses and Bsl = (11.0 ± 1.9) % using running quark masses. The uncertainty is dominated by unknown higher order perturbative corrections. We conclude that the present accuracy of the theoretical analysis does not allow to state a significant disagreement with the experimental results. However, our re-analysis of the decay b → ccs yields an increase of (35 ± 11) % due to next-to-leading order corrections including mass dependent terms, which further emphasizes the problem of the average charm quark content of the final states in B decays.

13 pp. (1986).

7 pp. (1985).

We calculate meson and baryon masses in quenched QCD for the small quark masses of phenomenological interest on a 10 3 × 16 lattice. We use Kogut-Susskind fermions which possess an explicit continuous chiral symmetry. We verify that this chiral symmetry is spontaneously broken and that for the physics involved our lattice is effectively of infinite volume at the quark masses we calculate. We verify m π 2 ∼ m q , which is what one expects for a Goldstone pion. For Λ mom = 200 MeV, which appears to be the consistent scale of quenched QCD, we find m q ≈ 7 MeV and the hadron masses m ϱ = (730 ± 90) MeV, m A1 = (1190 ± 90) MeV, m ϵ = (660 ± 50) MeV and m N = (920 ± 100) MeV. We also extract f π ≈ 134 MeV. In physical units our lattice is 3 fermi across.

9 pp. (1980)., Jets in e+e− annihilation are discussed in the context of perturbative Quantum Chromodynamics. Topics discussed include higher twist contribution, effects of quark masses and fragmentation on the 3 and 4 jet rates and some distributions bearing on the experimental verification of 4 jet events at the PETRA/PEP energies.

14 pp. (1980).

41 pp. (1986)., In these lectures I discuss the issue of the origin of the quark and lepton masses, both in the case in which these objects are elementary and in the case they are composite. Some of the generic predictionsand dynamical assumptions of GUTS, family symmetry models and super- strings are detailed. They are contrasted to the dynamics required for composite models of quarks and leptons. In this latter case, the diffi- culties of protecting dynamically fermion masses and yet still generat-ing intra and interfamily hierarchies is emphasized

23 pp. (1985).

(1980). doi:10.1007/BF01554399, The cross sectionsdσU,dσL,dσT anddσI fore+e−→q\(\bar q\)g are calculated for heavy quarks, and the resultant angular distribution is discussed.

230956 60 pp. (1987)., In these lectures I discuss mass issues both In QCD and in the standard electroweak theory. Among the topics treated are masses In the Goldstone sector of QCD, electromagnetic mass shifts and the values of quark masses. Issues connected with the Higgs mechanism and the generation of fermion masses and mixings are also examined, as well as the effect of radiative corrections for the W and Z masses. A general discussion of the U(1) problem, θ-vacua and the strong CP puzzle is given. The consequences of solving the strong CP puzzle by Imposing an additional chlral symmetry In the electroweak interactions are explored and some of the phenomenology of axions is reviewed. The possibility of constructing variant axion models, motivated by recent observations at GSI, is briefly touched upon in closing.

11 pp. (1981).

55 pp. (1986).