Studies of $\Lambda^0_b$ in ATLAS: decays to charmonium states and parity violating asymmetry

The results of ATLAS measurements of $\Lambda^0_b$ lifetime and decay asymmetry parameter in $\Lambda^0_b\to J/\psi\Lambda$ using 2011 7 TeV data are presented. The measured value of $\Lambda^0_b$ lifetime is $\tau_{\Lambda^0_b} = 1.449\pm 0.036(\mathrm{stat})\pm 0.017(\mathrm{syst})~\mathrm{ps}$, and the parity violating decay asymmetry parameter is measured to be $\alpha_b = 0.30 \pm 0.16 ({\rm stat})\pm 0.06 ({\rm syst})$.