Search for low mass Z' signature in four muon final state with the ATLAS detector.

A search for a low mass Z' particle in final states with four muons will be reported. This search is motivated by a recently observed discrepancy by the LHCb Collaboration in the rare decay of B meson to electrons and muons. A new physics model intending to describe the observed anomaly introduces a new neutral vector boson, Z', that only couples to muons and taus. We conducted a search through the 'radioactive' Z-->mu mu decays, where one muon radiates a Z' boson, which then decays to a pair of muons ($\mu^+ \mu^-$). This search uses the full data-set collected by the ATLAS detector in Run 2 with a total luminosity of 140 fb^-1 and is sensitive to Z' bosons in the mass range 5 to 70 GeV.