B-physics in ATLAS

A survey of B-physics and quarkonium production studies in ATLAS experiment is presented, on the data acquired from $pp$ interactions at $\sqrt s = 7 : TeV$ at LHC. A new bottonium state, the $\chi_b(3P)$ has been discovered. Differential cross sections of prompt and non-prompt $J/\psi$ production are measured. Also, the cross sections of $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$ are measured. $b-$hadron production cross section is determined through semileptonic decays with muons. Precise measurements of $\Lambda_b$ baryon mass and lifetime are performed. A limit on branching ratio for decay channel $B_s\rightarrow \mu^+\mu^-$ is set, the $CP$-violating parameter $\phi_s$ and the lifetime difference between$CP-$ even and $CP-$odd $B_s$ decays are measured in the channel $B_s \rightarrow J/\psi \phi(1020)$.