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

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