Spectra and M1 decay widths of heavy-light mesons

The M1 decay widths of charm and bottom mesons and their excited states are sensitive to the relativistic aspect of the quark curl ent operators and o btain a significant contribution from the interaction current that is assoc iated with the scalar confining interaction between heavy quarks (Q) and li ght antiquarks ((q) over bar). Consequently they provide direct evidence on the latter. The spectra and the M1 transition widths of the D, D-S and B, B-S mesons and their orbital excitations are calculated here within the fra mework of the Blankenbecler-Sugar equation, which allows a covariant treatm ent, while retaining a formal similarity to the nonrelativistic approach. T he hyperfine interaction in the Q (q) over bar mesons is modeled by screene d gluon exchange, which shares many features with the instanton induced int eraction. The quality of the model is tested by calculation of the spectra and M1 decay widths of charmonium. (C) 2000 Elsevier Science B.V. All right s reserved.