Underlying-event Activity in Proton+Proton Collisions at RHIC by STAR
Underlying-event activity is defined as the soft particle production in proton+proton collisions which is not directly related to the final fragmentation of hard-scattered partons. Underlying-event measurements therefore provide a tool to study non-factorizable and non-perturbative phenomena. Systematic measurements of the relationship between the underlying event and jet processes provide a crucial test for the Monte Carlo modeling. In this talk, we will discuss the progress of underlying-event measurements in proton+proton collisions at RHIC by STAR and its comparison with Monte Carlo tuning.