Heavy quark expansion of ${\Lambda }_b\to {\Lambda }^{\ast }(1520)$ form factors beyond leading order

Abstract

I review the parametrisation of the full set of ${\Lambda }_b\to {\Lambda }^{\ast }(1520)$ form factors in the framework of Heavy Quark Expansion, including next-to-leading-order $\mathcal{O}({\alpha }_s)$ and, for the first time, next-to-leading-power $\mathcal{O}(1/m_b)$ corrections. The unknown hadronic parameters are obtained by performing a fit to recent lattice QCD calculations. I investigate the compatibility of the Heavy Quark Expansion and the current lattice data, finding tension between these two approaches in the case of tensor and pseudo-tensor form factors, whose origin could come from an underestimation of the current lattice QCD uncertainties and higher order terms in the Heavy Quark Expansion.

Comments: 19 pages, 3 figures; v2 conformal to published version