Heavy-light mesons in QCD

Abstract

This talk summarizes the study of the dynamics of the heavy-light \bar Qq open charm and beauty mesons obtained in [1] using QCD spectral sum rules (QSSR) and motivated by the recent experimental discovery of the D{sJ}(2317) and D{sJ}(2457) mesons. The important r\^ole of the chiral condensate <\bar\psi\psi> in the mass-splittings between the scalar-pseudoscalar mesons is emphasized. The emerging value of the running charm quark mass for reproducing the well-known D(0-) and Ds(0-) masses is: mc(mc)=1.13^{+0.08}_{-0.04} GeV, which confirms previous estimates from this channel [2]. Using this value, the sum rules give: M{Ds(0+)}= (2297+- 113) MeV, and a small SU(3) breaking: M{Ds{(0+)}}-M{D{(0+)}}= 25 MeV. Extending the analysis to the B-system, we find M{B(0+)}- M{B(0-)}= (422+- 196) MeV = M{Ds(0^+)}-M{Ds(0^-)}. Assuming an approximate (heavy and light) flavour and spin symmetries of the mass-splittings as indicated by the previous results, one also deduces M{D*s(1+)}= (2440+- 113) MeV. Finally, one also gets: f{D(0+)}= (217+- 25) MeV much bigger than f\pi=130.6 MeV, suggesting a large violation of the 1/sqrt{M_D} scaling, while the size of the SU(3) breaking ratio f{Ds(0+)}/f{D(0+)}= 0.93+- 0.02 is opposite to the one of the 0^- channel of about 1.14.