ar X iv : h ep - p h / 98 07 46 3 v 1 2 2 Ju l 1 99 8 IHEP - TH - 98 - 16 Nonperturbative Corrections to One Gluon Exchange Quark Potentials 1

ar X iv : h ep - p h / 98 05 46 8 v 1 2 6 M ay 1 99 8 COURSE HEAVY QUARK PHYSICS

ar X iv : h ep - p h / 98 04 39 7 v 1 2 4 A pr 1 99 8 Quark and Gluon Orbital Angular Momentum and Spin in Hard Processes ∗

We suggest a method of constructing gauge invariant quark and gluon distributions that describe an abstract QCD observable and apply this method to analyze angular momentum of a hadron. In addition to the known quark and gluon polarized structure functions, we obtain gauge invariant distributions for quark and gluon orbital angular momenta, and consider some basic properties of these distributi...

ar X iv : h ep - p h / 98 04 39 7 v 2 2 5 A pr 1 99 8 Quark and Gluon Orbital Angular Momentum and Spin in Hard Processes ∗

We suggest a method of constructing gauge invariant quark and gluon distributions that describe an abstract QCD observable and apply this method to analyze angular momentum of a hadron. In addition to the known quark and gluon polarized structure functions, we obtain gauge invariant distributions for quark and gluon orbital angular momenta, and consider some basic properties of these distributi...

ar X iv : h ep - p h / 98 08 49 1 v 1 3 1 A ug 1 99 8 Multiquark States in a Goldstone Boson Exchange Model

We discuss the stability of multiquark systems containing heavy flavours. We show that the Goldstone boson exchange model gives results at variance with one-gluon-exchange models.

ar X iv : h ep - p h / 98 05 23 2 v 1 6 M ay 1 99 8 Mass Corrections to the Tau Decay Rate

In this note radiative corrections to the total hadronic decay rate of the τ-lepton are studied employing perturbative QCD and the operator product expansion. We calculate quadratic quark mass corrections to the decay rate ration R τ to the order O(α 2 s m 2) and find that they contribute appreciably to the Cabbibo supressed decay modes of the τ-lepton. We also discuss corrections of mass dimen...