Minimum-Bias and Early QCD Physics in ALICE

Abstract

A Large Ion Collider Experiment (ALICE) is the dedicated heavy-ion experiment at the Large Hadron Collider (LHC). In addition to its heavy-ion physics program, it also has a rich proton-proton physics program benefiting from a detector with a low momentum cut-off (pT about 50 MeV/c) and a small material budget (about 11% of a radiation length until the outer wall of the main tracking detector, the Time-Projection Chamber). ALICE has excellent means of particle identification (PID) with methods ranging from specific energy loss and time of flight to transition and Cherenkov radiation. The good primary and secondary vertex resolution allows for measurements of strangeness and heavy flavor with low backgrounds. ALICE has taken proton-proton collision data at 0.9, 2.36, and 7 TeV. In this article results of the first minimum-bias and soft-QCD measurements are presented. Inclusive pseudorapidity, multiplicity, and transverse momentum distributions are discussed as well as distributions of identified particles including strange particles. Further, results on two-pion Bose-Einstein correlations and the antiproton-to-proton ratio in collisions at the LHC are shown.