COVARIANT GENERALIZATION OF THE ISGUR-SCORA-GRINSTEIN-WISE QUARK-MODEL

A fairly general Lorenta-covariant quark model of mesons is constructe d. It has several versions whose nonrelativistic limit corresponds to the well-known Isgur-Scora-Grinstein-Wise model. In the heavy-quark li mit, the covariant model naturally and automatically produces the heav y-quark symmetry results for meson decay constants and semileptonic de cay form factors. The meson decay constants and the Isgur-Wise functio ns are calculated for various versions of the covariant model and comp ared with other estimates. A general and adaptable structure of the co variant model ensures that it can be used to describe transitions invo lving light and/or heavy mesons.