Hadrons with charm and beauty

Abstract

By combining potential models and QCD spectral sum rules (QSSR), we discuss the spectroscopy of the$(b\bar c)$ mesons and of the (bcq), (ccq) and (bbq) baryons (q≡d ors), the decay constant and the (semi)leptonic decay modes of theB _c meson. For the masses, the best predictions come from potential models and read:$M_{B_c } = (6255 \pm 20)$ MeV,$M_{B_c^* } = (6330 \pm 20)$ MeV,M _Λ(bcu) =(6.93±0.05) GeV,M _Ω(bcs) =(7.00±0.05) GeV,M _Σ*(ccu) =(3.63±0.05) GeV andM _Σ*(bbu) =(10.21±0.05) GeV. The decay constant$f_{B_c } = (2.94 \pm 0.21)f_\pi$ is well determined from QSSR and leads to:Γ(B _c →v _ττ=(3.0±0.4)(V _cb /0.037)²×10¹⁰ s⁻¹. The uses of the vertex sum rules for the semileptonic decays of theB _c show that thet-dependence of the form factors is much stronger than predicted by vector meson dominance. It also predicts the almost equal strength of about 0.30×10¹⁰ s⁻¹ for the semileptonic ratesB _c intoB _s ,B ^* _s ,η _c andJ/ψ. Besides these phenomenological results, we also show explicitly how the Wilson coefficients of the 〈α _s G ²〉 and 〈G ³〉 gluon condensates already contain the full heavy quark$(\left\langle {\bar QQ} \right\rangle )$ and mixed-$(\left\langle {\bar QGQ} \right\rangle )$ condensate contributions in the OPE.