Measurements probing small-x physics using the ATLAS detector.

The high-energy pp collisions at the LHC provide unique opportunity to study particle flow and event shapes of the hadronic final state particles. Evolution of the event shape variables, such as the transverse thrust, thrust minor and transverse sphericity have been studied for minimum bias events. Particle distributions sensitive to the underlying event have been measured using calorimeter jet events. Separate inclusive jet and exclusive dijet event selections are included in this study for various observables. The production of jets in association with a vector boson is an important process to study the contribution of multi-particle interactions and for understanding the effect of QCD radiation on forward and central jet activity. ATLAS results on events with vector boson plus jets are compared with predictions from Monte Carlo simulations.