Qcd Sum Rules For The Ground State Of Many Sub-quality Research

In the mg- limit,the spin-flavor symmetry of the heavy quark system plays an important role in the heavy flavor physics. HQET(Heavy Quark Effective Theory) makes this symmetry explicit and proves to be a desirable framework to predict the properties of heavy hadrons.Due to the asymptotic freedom of QCD,the determination of heavy baryon mass spectroscopy must resort to non-perturbative technique. QCD sum rule is one of those approaches designed for analytic calculation and suitable for the preceding aim. The starting point of QCD sum rule is the so called correlation function. The main assumption of QCD sum rule is that,at the transition from perturbative to non-perturbative regime,the confinement effect can be described as the power corrections in the OPE. Once obtained the hadronic representation of the correlation function in consideration,QCD sum rule allows one to express the theoretical calculation via hadronic parameters. Thus one can derive the interested quantity.In this paper we use the QCD sum rule approach to calculate the masses of Ag and baryons to the QCD/MQ order within the framework of HQET. We compare the direct approach and the covariant approach to this problem. Two forms of currents have been adopted in our calculation and their effects on the results are discussed. Numerical results obtained in both direct and covariant approaches are presented. The effective mass obtained in this paper is A = 0.8 +0.1 GeV for AQ baryon and A = 1.0+0.1 GeV for baryon. The kinetic energy for AQ baryon is - = 0.4+0.1 GeV2 with interpolating current and - = 0.5+0.1 GeV2 with interpolating current in direct approach. The kinetic energy for Eg baryon is -= 0.7+0.2 GeV2 with interpolating current and - = 1.0+0.2 GeV2 with interpolating current in direct approach. In covariant approach,both currents give the same result,i.e.,for AQ baryon - = -(0.08+0.02) GeV2 and for baryon - = 0.11+0.03 GeV2. The splitting between spin 1/2 and 3/2 doublets derived from our calculation is 0.35+0.03 GeV2 which is in good agreement with the experiment.