Identification of very-low transverse momentum muons in the ATLAS experiment

The standard muon identification in the ATLAS experiment is optimized for muons with transverse momentum ($p$$_{T}$) above 5 GeV. However searches for low mass resonances and many B-physics studies often need to identify muons with lower ($p$$_{T}$), where standard algorithms suffer from large backgrounds originating from sources such as hadron decays in flight. A new $LowPt$ selection has been developed to allow optimal muon identification down to 3 GeV in $p$$_{T}$ using variables that are sensitive to track kinks in the inner detector and to the imbalance between momentum measured in the inner detector and in the muon spectrometer. The new $LowPt$ identification, analyzed in simulation and in data, shows good efficiencies for muons produced in hard collisions and is effective in rejecting backgrounds.