Subleading Isgur-Wise Function of ${\Lambda }_b\to {\Lambda }_{c1}$ using QCD sum rules

Abstract

Subleading Isgur-Wise form factor $\tau (v\cdot v^{\prime })$ at $\mathcal{O}(1/m_Q)$ for ${\Lambda }_b\to {\Lambda }_{c1}^{1/2,3/2}$ weak transition is calculated by using the QCD sum rules in the framework of the heavy quark effective theory (HQET), where ${\Lambda }_{c1}^{1/2}$ and ${\Lambda }_{c1}^{3/2}$ are the orbitally excited charmed baryon doublet with $J^P=(1^{-}/2,3^{-}/2)$. We consider the subleading contributions from the weak current matching in the HQET. The interpolating currents with transverse covariant derivative are adopted for ${\Lambda }_{c1}^{1/2}$ and ${\Lambda }_{c1}^{3/2}$ in the analysis. The slope parameter ${\rho }^2$ in linear approximation of $\tau$ is obtained to be ${\rho }^2=2.76$ and the interception to be $\tau (1)=-1.27$ GeV.

Comments: 21 pages, 4 figures