Leading Isgur–Wise form factor of Λb→Λc1 transition using QCD sum rules

The leading Isgur–Wise form factor ξ(y) parametrizing the semileptonic transitions Λb→Λ1/2c1ℓν̄ and Λb→Λ3/2c1ℓν̄ is calculated by using the QCD sum rules in the framework of heavy quark effective theory, where Λ1/2c1 and Λ3/2c1 is the orbitally excited charmed baryon doublet with JP=(1−/2,3−/2). The interpolating currents with transverse covariant derivative are adopted for Λ1/2c1 and Λ3/2c1 in the analysis. The slope parameter ρ2 in linear approximation of the Isgur–Wise function is obtained to be ρ2=2.01, and the interception to be ξ(1)=0.29. The decay branching ratios are estimated.