Study Of Semileptonic Decay Rates Of B Meson

In the m_Q→∞limit,the spin-flavor symmetry of the heavy quarks system plays an important role in the heavy flavor physics.This brings great comfort to the study of hadrons with only one heavy quark as well as to the theoretical simplifying.The Heavy Quark Effective Theory(HQET)makes this symmetry explicit and proves to be a desirable framework to predict the properties of heavy hadrons.As in QCD,due to the asymptotic freedom of the strong interaction,one must resort to the non-perturbative technique to calculate the non-perturbative part of the dynamics.QCD sum rule is one fully developed approach which is widely used.The main assumption of it 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 rules allow one to express the theoretical calculations via hadronic parameters. Thus one can derive the interested quantities.Since middle 1980s,the B-meson physics is still the most important field in the particle physics because the study of it needs a new theoretical framework and its decay processes imply abundant dynamical mechanism.Semileptonic decay is an important B decay mode.The study of it makes sense to the test of the standard model and the study of the CP violation.In this paper we review the current study of the semileptonic B decay,and deduce the differential decay rates of B mesons in ground state transition into the high excited charmed meson doublet(D₂^*',D₃)(S_l^P=5^2-)in the framework of HQET.We also calculate the Isgur-Wise function to the leading order.By use of it,we get the final value of the decay rates.Our result is in a good agreement with that of Colangelo.