The invariant and helicity amplitudes in the transitions ${\Lambda }_b\to {\Lambda }^{\ast }({\frac{1}{2}}^{\pm },{\frac{3}{2}}^{\pm })+J/\psi$

Abstract

We present results for the invariant and helicity amplitudes in the transitions ${\Lambda }_b\to {\Lambda }^{(\ast )}(J^P)+J/\psi$ where the ${\Lambda }^{(\ast )}(J^P)$ are $\Lambda (sud)$-type ground and excited states with $J^P$ quantum numbers $J^P={\frac{1}{2}}^{\pm },{\frac{3}{2}}^{\pm }$. The calculations are performed in the framework of a covariant confined quark model. This analysis is important for the identification of the hidden charm pentaquark states $P_c^{+}(4380)$ and $P_c^{+}(4450)$ which were discovered by the LHCb Coll. We also discuss the possible New Physics effects in the exclusive decays ${\bar{B}}^0\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$. We extend the Standard Model by taking into account right-handed vector (axial), left- and right-handed (pseudo)scalar, and tensor current contributions. The ${\bar{B}}^0\to D^{(\ast )}$ transition form factors are calculated in the full kinematic $q^2$ range by employing a covariant quark model.

Comments: 5 pages, 1 figure, talk given at "The European Physical Society Conference on High Energy Physics - EPS-HEP 2017" (5 - 12 July 2017, Venice, Italy)