Measurements of the ${\Lambda }_b^0\to J/\psi \Lambda$ decay amplitudes and the ${\Lambda }_b^0$ polarisation in pp collisions at $\sqrt{s}=7\text{TeV}$

Abstract

An angular analysis of ${\Lambda }_b^0\to J/\psi \Lambda$ decays is performed using a data sample corresponding to $1.0{\text{fb}}^{-1}$ collected in pp collisions at $\sqrt{s}=7\text{TeV}$ with the LHCb detector at the LHC. A parity violating asymmetry parameter characterising the ${\Lambda }_b^0\to J/\psi \Lambda$ decay of $0.05\pm 0.17\pm 0.07$ and a ${\Lambda }_b^0$ transverse production polarisation of $0.06\pm 0.07\pm 0.02$ are measured, where the first uncertainty is statistical and the second systematic.