The Semi-leptonic Form Factors Of Λ_b→Λ_c And (?)_b→(?)_c In QCD Sum Rules

This thesis uses the QCD sum rules to calculate the semi-leptonic form factors of theΛ_b→Λ_c/(?)_b→(?)_c transition for the first time,considering the perturbative contribution(dim-0),the quark condensate contribution(dim-3)and the mixed quark-gluon condensate contribution(dim-5).Since the contribution of gluon-gluon condensate is generally considered to be small,it is not considered in this article.This article first gives the interpolating currents of the initial and final states,and defines the correlation function.Then calculate the correlation function at the hadron level and the QCD level respectively.Finally,the correlation function expressions at the hadron level and the QCD level are equal,and use the quark-hadron duality to reduce the contribution of excited state and continuous spectra.In practice Borel transformation are usually adopted to improve the convergence in the quark-hadron duality and suppress the higher resonance and continuum contributions.This will extract the physical quantity we need.By studying two-point correlation function to obtain the pole residues of (?)_Q andΛ_Q.Since a stable Borel platform can be found,its accuracy is high.Through the study of the three-point correlation function,the semi-leptonic form factors of theΛ_b→Λ_c/(?)_b→(?)_c transition are extracted,and the results obtained are compared with other theoretical calculations and experimental results.Since no stable Borel parameter area was found,an uncertainty of about10%(25)20%was introduced to the form factors of Λ_b→Λ_c and (?)_b→(?)_c.Taking into account these uncertainties,our prediction of the form factors are consistent with the results of the lattice QCD.Finally,the obtained form factors can be applied to the semi-leptonic decay processes.