Quantum Chromodynamics and Charm. An Excursion into Theory

摘要

Theoretical foundations of dispersion charmonium theory are discussed. It is argued that for the contribution of virtual heavy quarks asymptotic freedom governs the amplitudes even at vanishing external momenta. The interaction of charmed quarks with external currents and usual hadrons is considered within the framework of the effective Lagrangian method. Heavy quarks induce an infinite series of local vertices in the effective Lagrangian which determines the low-energy amplitudes. These amplitudes are connected with cross sections for charm production by means of dispersion relations. The corrections due to strong interactions to the sum rules for charmonium and charmed mesons are found. The question is cosidered to which extent the charmed world is separated from the world of light quarks. Reviewed are the variety of the results based on the heavy quark expansion, e.g. photoproduction of charmed particles, and the effects of virtual charm in weak interactions of usual hadrons, etc. (Atomindex citation 10:422528)