A Measurement of the Underlying Event Distributions in Proton-Proton Collisions at $\sqrt{s}$ = 7 TeV in Charged-Particle Jet Events using the ATLAS Detector at the Large Hadron Collider

Underlying Event distributions are studied in events containing at least one charged-particle jet produced in proton-proton collisions at \sqrt{s} = 7 TeV. Jets are reconstructed from charged particles using the anti-kt algorithm with radius parameter R = 0.6. The jet with the largest transverse momentum ( \jetpt ) and |eta| < 1.5 defines the azimuthal phi direction. Distributions of the charged particle multiplicity, the scalar sum of the transverse momenta ( \pt ) of charged particles, and the average charged particle \pt are measured as functions of \jetpt in the transverse region ( \pi / 3 < | \phi | < 2 \pi / 3 ) for 4 GeV < \jetpt. The data are compared to predictions from the Monte Carlo generators which have been tuned to data from the Large Hadron Collider, and are found in to be good agreement.